MIKE 11 - HydroEurope
MIKE 11
A modelling system for Rivers and Channels
User Guide
DHI Software 2007
2
3
4 MIKE 11
Please Note
Copyright
This document refers to proprietary computer software which is protected by copyright. All rights are reserved. Copying or other reproduction of this manual or the related programs is prohibited without prior written consent of DHI Water & Environment (DHI). For details please refer to your 'DHI Software Licence Agreement'.
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The liability of DHI is limited as specified in Section III of your 'DHI
Software Licence Agreement':
'IN NO EVENT SHALL DHI OR ITS REPRESENTATIVES (AGENTS
AND SUPPLIERS) BE LIABLE FOR ANY DAMAGES WHATSO-
EVER INCLUDING, WITHOUT LIMITATION, SPECIAL, INDIRECT,
INCIDENTAL OR CONSEQUENTIAL DAMAGES OR DAMAGES
FOR LOSS OF BUSINESS PROFITS OR SAVINGS, BUSINESS
INTERRUPTION, LOSS OF BUSINESS INFORMATION OR OTHER
PECUNIARY LOSS ARISING OUT OF THE USE OF OR THE INA-
BILITY TO USE THIS DHI SOFTWARE PRODUCT, EVEN IF DHI
HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
THIS LIMITATION SHALL APPLY TO CLAIMS OF PERSONAL
INJURY TO THE EXTENT PERMITTED BY LAW. SOME COUN-
TRIES OR STATES DO NOT ALLOW THE EXCLUSION OR LIMITA-
TION OF LIABILITY FOR CONSEQUENTIAL, SPECIAL, INDIRECT,
INCIDENTAL DAMAGES AND, ACCORDINGLY, SOME PORTIONS
OF THESE LIMITATIONS MAY NOT APPLY TO YOU. BY YOUR
OPENING OF THIS SEALED PACKAGE OR INSTALLING OR
USING THE SOFTWARE, YOU HAVE ACCEPTED THAT THE
ABOVE LIMITATIONS OR THE MAXIMUM LEGALLY APPLICA-
BLE SUBSET OF THESE LIMITATIONS APPLY TO YOUR PUR-
CHASE OF THIS SOFTWARE.'
Printing History
August 2004
Edition 2004
5
6 MIKE 11
MIKE 11 1
Simulation Editor •
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River Network Editor •
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7
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Tabular view: Runoff / Groundwater Links
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Cross Section Editor •
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Additional features of the Raw Data editor
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‘Cross-sections’ pull down menu
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Processed data, Graphical View
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Importing cross sections using File Import
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Import Coordinates of Levee Marks
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Exporting cross sections using File Export
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Plotting Multiple Cross Sections
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Boundary Editor •
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8 MIKE 11
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Users Upgrading from MIKE 11 Version 2002 or Previous Versions
. . 193
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The Boundary Table - Upper Split Window
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Specifying the Boundary Description
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Specifying the Boundary Type, Data Type and File/Values
. . 200
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Quick set up of Graded Sediment Boundaries
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Copying Point Source Boundaries
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Rainfall-Runoff Editor •
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Urban, model A, Time/area Method
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Urban, model B, Time/area Method
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Flood Estimation Handbook (FEH)
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Methods for hydrograph Generation
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Generation of an Observed Flood Event
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9
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Land use definitions for QLSF method
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Default values for specific method
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5.10.1 Activating the Basin View
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5.10.5 Inserting Rainfall Stations
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5.10.6 Preparing Thiessen weights
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5.12 A Step-by-step procedure for using the RR-Editor
Hydrodynamic Editor •
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Contraction and expansion loss coefficients
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Additional output for QSS with vegetation
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Fully Dynamic and High Order Fully Dynamic
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10 MIKE 11
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6.11.1 Activation of Bed resistance Triple Zone Approach
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6.12.5 Reduction parameters (only encroachment methods 3 to 5)
. . 316
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6.12.7 Encroachment simulation overview
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6.12.8 Encroachment station overview
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6.12.9 General guide lines for carrying out encroachment simulations
318
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6.15.1 A step by step guide to generating two-dimensional maps
. . . 324
6.15.2 A step by step guide to generating Digital Elevation Models (DEM)
327
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6.20.1 Generating Time Series Output Files
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11
Advection-Dispersion Editor •
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Advection-Dispersion module (AD)
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Cohesive Sediment Transport module (CST)
. . . . . . . . . . 341
Advanced Cohesive Sediment Transport module (A CST)
. . 342
The Advection-Dispersion Equation
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Single layer cohesive component.
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WQ EcO Lab Editor •
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Sediment Transport Editor •
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Sediment transport simulations; Simulation mode
. . . . . . . 377
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Special features for specific transport models
. . . . . . . . . . 384
12 MIKE 11
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Preset distribution of sediment in nodes
. . . . . . . . . . . . . . . . . . 388
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Flood Forecasting Editor •
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
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10.1.1 Simulation Period and Time of Forecast
. . . . . . . . . . . . . 395
. . . . . . . . . . . . . . . . . . . . . . . . . . . 395
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
. . . . . . . . . . . . . . . . . . . . . . . . . . . 397
. . . . . . . . . . . . . . . . . . . . . . . . . . . 397
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
. . . . . . . . . . . . . . . . . . . . . . . . . . 398
10.2.5 Location of forecast stations
. . . . . . . . . . . . . . . . . . . . 399
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402
10.3.3 Boundary data manipulation
. . . . . . . . . . . . . . . . . . . . 402
10.3.4 Storing of Estimated boundaries
. . . . . . . . . . . . . . . . . . 405
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408
Data assimilation editor •
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409
. . . . . . . . . . . . . . . . . . . . . . . . . . . 411
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412
. . . . . . . . . . . . . . . . . . . . . . . . . . . 412
. . . . . . . . . . . . . . . . . . . . . . . . . . 413
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414
. . . . . . . . . . . . . . . . . . . . . . . 415
. . . . . . . . . . . . . . . . . . . . . . . . . . 415
13
. . . . . . . . . . . . . . . . . . . . . . . . . 416
. . . . . . . . . . . . . . . . . . . . . . . . 417
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418
. . . . . . . . . . . . . . . . . . . . . . . . 421
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
11.5 Standard deviation editor
. . . . . . . . . . . . . . . . . . . . . . . . . . 424
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427
11.7 A step by step guide to uncertainty assessment
11.8 A step by step guide to updating using the Kalman filter method
11.9 A step by step guide to updating using the Weighting function method
431
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432
11.10.1 Uncertainty assessment on hydrodynamic simulation
. . . . . 433
11.10.2 Kalman filter updating on hydrodynamic set-up
. . . . . . . . . 433
11.10.3 Uncertainty assessment on advection dispersion simulation
. 434
11.10.4 Kalman filter updating on advection dispersion set-up
. . . . . 435
Batch Simulation Editor •
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437
. . . . . . . . . . . . . . . . . . . . . . . . . . . 439
12.1 Setting up a Batch Simulation
. . . . . . . . . . . . . . . . . . . . . . . . 439
Appendix A •
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
A.1 FLOW RESISTANCE AND VEGETATION
. . . . . . . . . . . . . . . . . . . . 445
A.1.1 Flow Channels in Halkær Å
. . . . . . . . . . . . . . . . . . . . . . . . . 445
A.1.2 Laboratory measurements using Bur Reed
. . . . . . . . . . . . . . . . 447
A.1.3 Experiments in ‘Kimmeslev Møllebæk’
. . . . . . . . . . . . . . . . . . . 448
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450
Appendix B •
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453
B.1.2 Converting set-ups from v. 3.2 and prior
. . . . . . . . . . . . . . . . . . 454
B.1.3 Converting simulation results to text files
. . . . . . . . . . . . . . . . . 454
14 MIKE 11
S I M U L A T I O N E D I T O R
15
16 MIKE 11
Models
1 SIMULATION EDITOR
The simulation editor serves three purposes:
1 It contains the simulation and computation control parameters.
2 It is used to start the simulation.
3 It provides a link between the network editor and the other Mike11 editors. The editing of cross sections is a typical example of this link, where the graphical view of the network editor is used to select cross sections from the cross section editor. The linkage requires a file name to be specified for each of the required editors. The file names are input
on the Input Property Page of the simulation editor. An alternative is to
select a file from the File Menu which will recall the appropriate editor.
The edit menu can then be used to edit the objects
1.1
Models
Simulation Editor
Figure 1.1
The Models tab. Note that the Simulation Mode Box may differ if a quasi two dimensional steady state solver with vegetation is not installed.
17
Simulation Editor
This page is used to define the simulation models to execute and the simulation mode (unsteady or quasi steady).
1.1.1
Models
The following abbreviations of module names are used:
HD Hydrodynamic
AD Advection-Dispersion
ST Sediment Transport
ECO Lab(Including Water Quality modelling etc.)
RR Rainfall-Runoff
FF Flood Forecast
DA Data assimilation
Ice River Ice modelling
Some of the model that can be selected are dependent on other modules in a simulation and it is therefore required to have more modules selected.
Roules for model-dependency is implement such that once a model is selected, an automatic selection of eventual dependent models will be made (e.g. Selection of FF-model selects HD-model also, Selection of
ECOLab selects AD-model also etc.).
Selecting a hydrodynamic model an additional tick box entitled
‘Encroachment’ becomes active. When selecting the latter all other tickboxes become inactive since the encroachment module is only designed to function in conjunction with the hydrodynamic module. Further when carrying out an encroachment simulation please ensure that the simulation mode is set to ‘Quasi steady’. If the latter is not the case the program will issue a warning and terminate.
Water Quality modelling takes place through the ECO Lab model entry where a variety of Water Quality models can be selected from so-called
ECO Lab templates.
1.1.2
Simulation Mode
Unsteady
The HD calculations are based on hydrodynamic flow conditions.
18 MIKE 11
Input
1.2
Input
Quasi steady
At every time step the calculations are based on steady flow conditions.
If a quasi two dimensional steady state solver with vegetation is not
installed the Simulation Mode Box will differ from Figure 1.1. Otherwise
a total of four possible settings are available:
1 QSS default: The classic MIKE 11 steady state solver is used.
2 QSS with vegetation: The quasi two dimensional steady state solver with vegetation is used for the simulation.
3 QSS with energy equation: A submodule of the quasi two dimensional steady state solver with vegetation. The energy equation is used for obtaining the water level in the network.
4 QSS with Ida’s method: A submodule of the quasi two dimensional steady state solver with vegetation. An approximate solution of the governing equation (Ida’s method) is used for obtaining the water level in the network.
Simulation Editor
Figure 1.2
The Input tab.
19
Simulation Editor
Based on the model selection from the Models Property Page a number of
filename fields becomes active, and the user is required to specify a range of input file names.
This button opens a file selection box.
This button opens the relevant editor if a valid filename of the given file-type has been specified in the filename field.
Note that the files required are indicated by the active fields, but two exceptions exists; those are the fields for the result files. It is important to notice, that files specified in the Models page are all input files for a simulation, so these result-file fields are Not result-filenames for the simulation. Result file-names are specified in the ‘Results’ page.
A hydrodynamic result file (HD Results) is only required if: z a stand alone Advection-Dispersion or Sediment transport simulation is to be carried out where hydrodynamic conditions/results are read from results of a previous HD-simulation, or z if lateral sources from a previous MIKE SHE/MIKE 11 coupled model run are to be included in a hydrodynamic simulation.
A Rainfall Runoff result file (RR Results) is only required if the hydrodynamic and rainfall model are to run uncoupled. That is, the Hydrodynamic model reads runoff input to the river modelling from the RR Results-file.
1.3
Simulation
The simulation property page contains details of simulation time, time stepping specifications and initial conditions for each of the chosen types of models.
20 MIKE 11
Simulation
Figure 1.3
The Simulation tab.
1.3.1
Simulation Period
Time step type
The Time step type is specified as either: Fixed time step, Tabulated time step or Adaptive time step. In case fixed time step is selected the time step is specified in the editable field with heading time step and the unit is selected in the unit selection list.
In case the time step type is specified as ‘Tabulated’, the time steps are specified by activating the settings button and selecting a timeserie from a
time series file (dsf0) in the dialog presented in Figure 1.4. The timeseries
file must contain at least one tem defined as Item-type ‘TimeStep’.
Simulation Editor
Figure 1.4
Dialog for specification of the tabulated time step time series file.
21
Simulation Editor
In case the time step type is specified as ‘Adaptive time step’, settings for time step adaptation is similarly specified in a dialog activated by the Set-
tings button. This dialog is presented as Figure 1.5.
22
Figure 1.5
Time step settings for adaptive time stepping.
Minimum/maximum/unit
Defines the limits for the adaptation of the time step.
Change ratio
The time step is successively lowered with change ratio until the criterias specified in this menu are met. The starting value for the adaptation within the time step is change ratio times the previous time step.
Criterias
The time step adaptation model offers seven criteras which may each be enabled or disablet and given threshold values.
z
|resid(BC)/BC| is a measure for the largest acceptable error introduced at the boundaries. Mike 11 interpolates the boundary values between t and t+
∆t using liniar interpolation. In case the boundary values has a resolution finer than
∆t this may introduce unfavourable behaviour where details are negleclted. The term resid(BC) describes the residual between the actaul value in the time series boundary conditon (BC) file and the value found using linear interpolation between t and t+
∆t. The term BC refers to the actual value in the time series boundary conditon file.
MIKE 11
Simulation z z z z z
|delQ| is a meausre for the largest accetable discharge change anywhere in the grid within a time step. The criteria helps to lower the time step when sudden changes appears in the discharge. The changes may be either physical changes due to a sudden increase in inflow for instance or mathematical changes due to numerical instability. In either case a decrease in time step may well be desireable.
|delQ/Q| is a measure for the largest acceptable relative discharge change anywhere in the grid within a timestep.The criteria helps to lower the time step when sudden changes appears in the discharge. The changes may be either physical changes due to a sudden increase in inflow for instance or mathematical changes due to numerical instability. In either case a decrease in time step may well be desireable. The criteria is well suited for dam break studies where it cn be used for refining the time step in the period after the break.
|delh| is measure for the largest acceptable water level change anywhere in the grid. As for the |delQ| and |delQ/Q| criterias this criteria helps lowering the time step when large changed appears in the water level due to either physical changes or mathematical instabilities.
|delh/h| is measure for the largest relative acceptable water level change anywhere in the grid. As for the |delQ|, |delQ/Q| and |delh| criterias this criteria helps lowering the time step when large changed appears in the water level due to either physical changes or mathematical instabilities.
|Courant| (HD) specifies the maximal allowed courant number within the grid and time step.
Cr
=
(
v
+
gD
∆x
)∆t
The courant number, defined above, expresses the length in terms of grid cells that information travels within a time step. The HD Courant number refers to the momentum equation and
∆x is hence in this contxet the distance between two h-points.
Mike 11 applies a 6-point Abbott scheme for solving the equation which does not have the typical Courant number below one demand.
Good results are obtained up to Courant numbers as high as 10-20.
Simulation Editor
23
Simulation Editor z
|Courant| (AD) specifies the maximal allowed courant number for the advection dispersion calculation.
Cr
=
The AD Courant number, defined above, is a measure for the length in terms of grid cells that the species are convected within a time step.
The applied computational scheme is stable for AD Courant numbers less than 1. The AD solver includes both h- and Q- points as species grid points, hence the
∆x is half the distance between two h-points when calculating the AD Courant number.
The criteria is well suited for ensurig stability of AD calculations by lowering the time step when the flow velocity increases and increasing the time step when the flow velocity decreases.
Period
The date and time for the start and end of the simulation period. The standard windows date time format is used.
The ‘Apply Default’ button can be used to extract the possible simulation start-time and end-time. Once the button is activated a search of time-intervals in the timeseries files active for the actual simulation takes place and the earliest possible start-date and latest possible enddate is automatically transferred to the Period date-fields. If no dates are proposed from activating the button the most likely reason will be that there are no overlapping timeseries in the setup.
ST Time Step Multiplier
The ST module may not operate using the same time step as the HD model. The ST Time Step Multiplier specifies the ST time step as a multiple of the HD time step.
RR Time Step Multiplier
The RR module may not operate using the same time step as the HD model. The RR Time Step Multiplier specifies the RR time step as a multiple of the HD time step.
1.3.2
Initial Conditions
For each of the modules HD, AD, ST and RR the following can be specified:
24 MIKE 11
Simulation
Type of condition
– Steady State: HD only. The initial conditions will be calculated automatically assuming a steady state condition with discharges and water levels at the boundaries corresponding to the start time of the simulation.
– Parameter File: The initial conditions will be taken from the parameter file relevant to the module in question.
– Hotstart: The initial conditions will be loaded from an existing result file.
– Steady+Parameter: HD only. The initial conditions will be established using both the steady state and parameter file method. In
those grid points where data are specified in the Initial (p. 302)
Property Page of the Hydrodynamic Editor (p. 293) the initial con-
ditions will be taken from the parameter file, other grid points will be calculated using the steady state option.
Hotstart Filename
The name of the existing result file from which the initial conditions should be loaded.
Add to File
The results of the current simulation will be added to the end of the hotstart file. Any information (in the hotstart file) after the simulation start date will be lost. This part of the file will be replaced by the new simulation results.
Hotstart Date and Time
The date and time at which the initial conditions are loaded from the hot-
start file. If the “Add to File” has been selected the hotstart date and time
will be taken as the simulation start.
Simulation Editor
25
1.4
Results
Simulation Editor
26
Figure 1.6
The Results tab.
For each of the modules selected on the Models Property Page the user
should specify a filename for saving of the simulation results.
The filename can not be edited if the flag “Add to File” has been selected
on the Simulation Property Page. In this case the selected hotstart file will
become the result file as well.
Storing Frequency and Unit
To limit the size of the result files the user can specify a save step interval.
The storing frequency may be specified either as the number of time step intervals between each saving of the results or as specific time. The latter, however, requires that the the specified storring time frequency is a multiplum of the time step.
MIKE 11
Start
1.5
Start
Simulation Editor
Figure 1.7
The Start tab.
If all specified input files exist, the “Start” button can be pressed and the simulation will commence. The simulation will take place as a separate process (MIKE11.EXE) and the progress of the simulation is presented in the progress bar in the bottom of the dialog.
Any error or warning message from the simulation will be saved in a file with the same name as the simulation file and a .log extension. The logfile is saved in the same folder as the simulation file used for the actual simulation and if required, it can be opened from this folder using Notepad or other text-editors. Should any errors or warnings occur during simulation, these are presented immediately in the Validation field just above the progress bar.
Upon completion the simulation results can be viewed using MIKE View.
27
Simulation Editor
28 MIKE 11
R I V E R N E T W O R K E D I T O R
29
30 MIKE 11
Graphical View
2 RIVER NETWORK EDITOR
The River Network Editor gives an overview of the current setup and provides a common link to the various MIKE 11 editors. The network editor has two main functions:
1 River network input and editing.
2 Overview of all model information in the current simulation.
The former includes:
– Digitising river networks and branch connections.
– Definition of hydraulic structures (weirs, culverts etc.).
– Definition of catchment inflow points (for rainfall run-off model).
The editor provides an overview display in a graphical window. Settings for the graphical view are found in the Settings menu.
The current simulation setup is defined using the Simulation Editor
NOTE: Cross sections are edited using the River Cross Section Editor
(p. 153), which is accessible from the River Network Editor.
Some of the features available in the Network Editor have been developed in cooperation with CTI Engineering, CO., Ltd., Japan. Amongst these are; Tabulated structures, Honma's weir formula, bridges (D’Aubuisson and submerged bridge), Routing along channels, Outflow from
Dams/retarding basins and the Steady flow with vegetation.
2.1
Graphical View
The graphical view is the default view and will be activated automatically when a river network file is opened or created. Additional graphical views can be opened using the New Window item under the Window Menu.
Editing of the river network (i.e. the points and branches) is undertaken using the Graphical Editing Toolbar. Editing tools are also found using the
Pop-Up Menu (right mouse button) these include insert, edit and delete functions. Typically the Pop-Up Menu is used for editing of cross section geometry, parameters, hydraulic structures and data held in other MIKE
11 editors. Note that to access information from another editor other than the Network Editor, an editor file name must be specified using the Simulation File Editor.
River Network Editor
31
River Network Editor
Example of insertion of a Catchment link using the Pop-Up menu is
Figure 2.1
Illustration of right mouse pop up menu from where all data editors can be accessed.
2.1.1
File Menu
Import
Point and Branch Data from Cross-Section ASCII File
If a cross section file has been exported to a text file this text file can be imported to the network editor. In this way point and branch information is passed from the cross section file to the network file. Please note that this option only is relevant when the cross section file holds information about the coordinates.
Point and Branch Data from Point-Branch ASCII File
Point and branch information can be read into the network file using a text file with the following format: x-coordinate y-coordinate Branch_Name Chainage
32 MIKE 11
Graphical View
Alignment Points and Lines from PFS Files
This feature is only appropriate if the Quasi Two Dimensional steady state with vegetation module is used. It provides a way of importing alignment line data into a setup. The data in the file must be of the form shown in
Figure 2.2. The file should contain a section of the type “[AlignmentLine]
... EndSect // AlignmentLine” for each alignment line.
Figure 2.2
The format used for importing alignment line data.
2.1.2
View Menu
Project Explorer and Start Page
With the two top most items in the view menu you can hide or show the
Start Page and the Project Explorer. For further documentation in these features please refer to the general documentation for MIKE Zero.
Tabular view
Used when the tabular view of the network file must be shown.
Longitudinal Profile View
Used to select a longitudinal profile for viewing. Select the profile by clicking the mouse at the first and at the last branch to be included in the profile.
Query Last Profile Search
Selecting a longitudinal profile in a looped network by clicking at the first and the last branch in the profile sometimes results in more than one profile. All the possible profiles can be examined by using the ‘Query Last
Profile Search’ option.
River Network Editor
33
River Network Editor
34
Figure 2.3
Menu used to select between several possible longitudinal profiles.
Network
Here the presentations of the different network objects can quickly be turned on or off. For a more detailed layout of the graphical view see
Boundary
Here the presentations of the different boundary types can quickly be turned on or off. For a more detailed layout of the graphical view see
Hydrodynamic Parameters
Here the presentations of the different hydrodynamic parameters can quickly be turned on or off. For a more detailed layout of the graphical
Advection Dispersion Parameters
Here the presentations of the different advection dispersion parameters can quickly be turned on or off. For a more detailed layout of the graphical
Sediment Transport Parameters
Here the presentations of the different sediment transport parameters can quickly be turned on or off. For a more detailed layout of the graphical
Draw Grid
The drawing of the grid can be switched on and off by using this option.
MIKE 11
Graphical View
Export Graphics
The graphical view can be exported in the following ways:
– Copy to Clipboard.
– Save to metafile.
– Save to bitmap.
– Export layer graphics to file.
2.1.3
Network Menu
Resize area
Figure 2.4
Menu for resizing the area of the graphical view.
The graphical view can be resized by entering the minimum and maximum coordinates for both the x-axis and the y-axis.
Secondly, the map projection for geo-references can be specified here.
Snap Insert Objects to Points
Here the ‘Snap Insert Objects to Points’ option can be switched on and off.
Auto Connect Branches
When selecting this option all the branches are automatically connected.
The method used to connect the branches can be selected in Network data
Disconnect All Branches
Choosing this options will remove all branch connections.
Generate Branches from Shape files...
Selecting this item will open a dialog that allows for utilizing information in Shape files for automatic generation of points and/or branches. Before
River Network Editor
35
River Network Editor information in a Shape file can be used the file must be loaded as a background picture through the Layers menu in main menu bar.
Shapes file with point information can be used for generating points, and
Shape files with polylines can be used to generate points and branches, or only points.
Auto Boundary (..) Free Branch Ends
This feature will create boundaries in the boundary file for all free branch ends. It will be done for the HD module, the AD module or the ST module
depending on the selections in Network data (p. 39).
Auto Update Chainages
When this option is selected the chainages of the points will be updated automatically.
Update Chainages
This option is only meaningful if the Auto Update Chainages option is not selected. The Update Chainages option could be used after having moved one or several points.
Number Points Consecutively
Figure 2.5
The menu in which the number of the first point can be entered.
When joining two network files (see B.1.1 Merging .pfs files (p. 453)) it is
necessary that the number of the points in the two files do not overlap. To avoid this it is possible to renumber the points in one of the network files.
2.1.4
Layers Menu
Add/remove
It is possible to import background maps into the graphical view of the network file. The following file types can be used: Image files (.bmp, .jpg and .gif) and Shape files. When loading image files the geo-reference is automatically set to (0,0) and (10000, 10000) for lower left and upper
36 MIKE 11
Graphical View right corner respectively. This can be changed using the item “Properties...” in the Layers menu.
Properties...
This item will open a dialog that allows for setting the properties for the loaded image and shape files.
For image files this includes the display style and the geo-reference. Both settings are saved in the .nwk11 file.
For shape files this includes the graphical setting for points, lines and text.
2.1.5
Settings Menu
Network
The network settings dialog contains the following property pages: z z z z
Graphics
River Network Editor
Figure 2.6
The Graphics property page.
37
River Network Editor
This property page controls the layout of the graphics.
On the left hand side, the dialog shows the items organized in a tree structure. Each graphical item has branches for points, lines, labels etc. By selecting a branch it’s settings can be changed in the right hand side of the dialog.
It is also possible to control if items are displayed or not by using the right mouse button on a branch. This can be done on different levels in the tree.
Mouse
38
Figure 2.7
The Mouse property page.
This property page sets the properties for the mouse. This minimum distance for which a new point is generated when digitizing is set by using the ‘Digitize Distance’ field. The radius in pixels for which the mouse detects points can be set in the ‘Mouse Sensitivity’ field.
MIKE 11
Graphical View
Network data
River Network Editor
Figure 2.8
The Network Data property page.
– Auto Connect Branches
Search Distance: The maximum search radius applied when using
the Auto Connect Branches facility under the Network Menu can be specified here.
Connect to: The automatic connection can either be made to the
nearest point or to the nearest branch segment.
– Auto Boundary Free Branch Ends
The facility Auto Boundary Free Branch Ends can generate boundary conditions for the HD, AD or ST models. The desired models are selected here.
– Cross section drawing style
The cross section drawing style may be set to uniform or automatic
– Snap to grid
This facility may be used for snapping points to a user defined grid.
The spacing of the grid may be defined here as well.
Note the grid spacing used for snapping is not shown.
39
River Network Editor
– Default branch type
The default type of branch is set here. The user can chose between
Regular, Link Channel and Routing.
The Rotate Branch Graphical Symbols checkbox enables the rotating of graphical symbols such as triangles, rectangles etc. on the plan plot. Without the activation of this checkbox symbols are always oriented ’north-south’ but if the feature is enables, the symbols will be oriented towards the direction of the river branches, see
40
Figure 2.9
Illustration of ’Rotate Symbols’ feature in MIKE 11 Network Editor
– Cross section chainage correction
This switch may be used if chainage corrections should be drawn.
MIKE 11
Tabular view: Network
Select and edit
Figure 2.10
The Select and Edit property page.
Here the user specifies which editors are to be included when using the
Select & Edit tool.
Font
Here it is possible to select the font used in the graphical view.
2.2
Tabular view: Network
The tabular view gives an overview of branches, structures, rainfall catchments etc.
2.2.1
Points
The position of the points in the network may edited here. The dialog is
River Network Editor
41
River Network Editor
42
Figure 2.11
The points property page.
Definitions
The X- and Y-coordinate of the present point may be edited here.
Attributes
Different attributes are available for editing.
Chainage type
The chainage may either be chosen as user defined or system defined.
Chainage
If the chainage type is set to user defined the chainage may be edited using this box.
Type
The type of the point may be set here. Three types are available:
1 Default: The point is neither an h- or a Q-point.
2 Forced h-point: The point is used as an h-point.
3 Forced Q-point: The point is used as an Q-point.
Branch
This displays the river branch to which the present point belongs and is only for verification purposes.
Overview
An overview of the points is given in this box.
MIKE 11
Tabular view: Network
2.2.2
Branches
Branches and points can be inserted or deleted from existing branches using the Graphical Editing Toolbar.
Alternatively the branch dialog may be used (see Figure 2.12).
Figure 2.12
The branch property page.
Definitions
Branch name
Name of the branch.
Topo ID
Topo ID.
Upstr. Ch.
The chainage of the first point in the branch.
Downstr. Ch.
The chainage of the last point in the branch.
Flow Direction
If specified as positive, simulated discharges will be positive when the flow direction is from upstream chainage to downstream chainage. Vice versa if the flow direction is defined as negative.
River Network Editor
43
44
River Network Editor
Maximum dx
Maximum distance between to adjacent h-points. See Tabular View: Grid
Branch Type
– Regular: A minimum of one cross section is required
– Link Channel: No cross sections are required. Instead the parameters given in the Link channel dialog must be specified using the
Edit Link Channel Parameters button. Note that LINK channels are
ONLY to be used when conducting Hydrodynamic simulations.
– Routing: No cross sections are required. Only the flow is calculated,
no water levels. See section 2.4 Tabular view: Routing (p. 127).
– Kinematic Routing: Kinematic Routing can be used to model the hydraulics of upstream tributaries and secondary river branches, where the main concern is to route water to the main river system.
The Kinematic Routing method does not facilitate the use of structures at Kinematic Routing branches. Moreover, the method does not account for backwater effects.
At Kinematic Routing branches, it is possible to run the model without information on cross-sections. In turn, this indicates that Kinematic Routing branches can not be used to model a looped part of a river network. Employment of Kinematic Routing branches requires that all branches located upstream of a Kinematic
Routing branch are defined in the same way.
– Stratified: If stratified flow is to be included in the simulation. The branches for which this vertical resolution is required are to be specified as stratified.
Connections
The connection point of one branch to another can be specified here. However, it is recommended that branch connections be defined using the Connect Branch tool in the Graphical Editing Toolbar.
Edit Link Channel Parameters
This option is available when the branch type has been set to link channel.
Purpose
The link channel is a short branch used to connect a flood plain to the main river branch. Link channels do not require cross sections to be specified and are consequently simpler to use than regular channels. The link is modelled as a single weir branch and will contain only three computation points. Further the internal description of the link channel restricts its use
MIKE 11
Tabular view: Network to hydrodynamic simulations ONLY. Thus if sediment transport , advection dispersion etc are to be carried out the set-up should be void of link channels.
River Network Editor
Figure 2.13
Link channel property page.
The link channel dialog (see Figure 2.13) is used for specifying all param-
eters appropriate for the link channel e.g. geometry, head los coefficients etc.
Geometry
The longitudinal geometry is defined from the following parameters:
Bed Level US: Upstream bed level of the link channel.
Bed Level DS: Downstream bed level of the link channel.
Additional Storage: Link channels do not contain cross sections and
do not contribute to the storage capacity at nodal points where the link connects to a main branch. The Additional Storage parameter can be used to avoid zero storage at nodal points to which only link channels and no regular channels are connected.
45
River Network Editor
The combo box defines if additional storage is to be added at the upstream, downstream or both ends of the link channel. The actual storage is specified in the additional flooded area column of the processed data on a cross section page.
Bed resistance
The bed resistance along the length of a link channel can be described using Manning's M or Manning's n.
Head Loss Coefficients
All four factors are dimension less and must be within the range 0.00 -
1.00.
Cross Section Geometry
A depth-width table defines the cross section geometry of a link channel.
Both the depth and the width must be increasing.
Q/h - relations
To calculate the Q/h relationship, specify the number of relationships required and press the Calculate button. The result of the calculation will appear in the table. If any of the parameters defining the link channel are changed the Q/h relations must be re-calculated.
2.2.3
Alignment Lines
The alignment lines features are part of the quasi two dimensional steady state with vegetation module.
Purpose
The purpose of using alignment lines is to save geo-referenced information in the network editor, and to utilize this information to update information in the cross section editor. Alignment lines information in the network file will influence the simulation results only when transferred to the cross section editor, and such transfer is requested in the cross section editor. The information in the cross section editor which is subject to be updated as the result of transferring alignment line information is:
– Positions of markers indicating left and right bank/levee (marker 1 and 3), left and right low flow bank (marker 4 and 5), and lowest point (marker 2).
– Zone classification.
– Vegetation height.
– Angle between cross section and direction of flow/branch.
46 MIKE 11
Tabular view: Network
Definition.
An alignment line is similar to a branch in the sense that it is a line going through an ordered list of points with x- and y- coordinates. The following list of types of alignment lines are available:
– Left levee bank.
– Right levee bank.
– Left low flow bank.
– Right low flow bank.
– Thalweg.
– Vegetation zone.
An alignment line must belong to a branch in order to be taken into account. Only one alignment line of each type can belong to a branch.
However, with the exception that any number of vegetation zones can be belong to a branch.
User Interface
Figure 2.14 shows the property page for alignment lines. Each alignment
line is shown as a row in the overview in the bottom of the dialog, and the x- and y-coordinates of the points along the actual line (the line in the row being high lighted in the overview) is shown in the details in the top of the dialog.
River Network Editor
47
River Network Editor
48
Figure 2.14
The alignment lines property page.
Depending on the type of alignment line there may, in addition to the x- and y-coordinates, be other data shown in the details part of the dialog.
These additional data are:
– Left and right bank: Each pairs of expansion and contraction lines creates a dead water zone along the bank. The dead water zone is defined by the bank line between the expansion and the contraction point, and by two straight lines starting at the expansion and the contraction point. Each of these lines are defined by two angles.
One being the angle (relative to the x-axis of the coordinate system) of an artificial guide line parallel to the main flow direction, and one being the angle between the guide line and the dead water line.
– Vegetation zone. A vegetation height is assigned to each vegetation zone. Similar to the dead water zone adjacent to an expansion there is a dead water zone downstream of a vegetation zone. There are two straight lines pointing in the downstream direction which defines the dead water zone. These lines are each defined by two angles. One being the angle (relative to the x-axis of the coordinate system) of an artificial guide line parallel to the main flow direction, and one being the angle between the guide line and the dead water line.
MIKE 11
Tabular view: Network
Figure 2.15
Definition of dead water zone along bank.
River Network Editor
Figure 2.16
Definition of dead water zone behind vegetation zone.
The x- and y-coordinates for the points along the alignment lines can be edited in three ways: 1) Using the tools available in alignment lines tool
bar in the graphical view (see 2.7.2 Tool Bar for Alignment Lines
(p. 148)). 2) Editing the numbers in the tabular view. 3) Using the File
menu to import the coordinates from a text file.
Figure 2.17 shows a river network including alignment lines as visualized
in the graphical view of the network editor.
49
River Network Editor
Once the alignment data are added, the information is ready to be transferred to the cross section editor.
Figure 2.17
Example of a river network with alignment.
2.2.4
Junctions
The junctions feature is part of the quasi two dimensional steady state with vegetation module.
50 MIKE 11
Tabular view: Structures
Figure 2.18
The Junctions dialog.
Details
Name, Name2 and Name3: The river name of the three rivers meeting at
the junction.
Chainage, Chainage2 and Chainage3: The chainage of the three rivers
meeting at the junction.
Width of Channel1, Channel2 and Channel3: User defined width of the
respective channels.
Angle 1 and Angle 2: The direction angle of channel 1 and 2 with respect
to channel 3.
Distance along channel 3 (D): The distance along channel 3 at which the
local water depth should be used for the determination of the water level in the downstream points of channel 1 and 2.
2.3
Tabular view: Structures
2.3.1
Introduction
A Number of Structures such as weirs, culverts, bridges etc. may be included in the river network set-up. The flow through most of the structures is modelled using the energy equation allowing inclusion of local
River Network Editor
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River Network Editor head losses, but equations such as weir formuals are also available. The effect of the bed friction is generally not taken into account thus it is recommended that the h-points up- and downstream are situated close to the structure.
Structures are always located in Q-points in which the momentum equation is normally solved, and the reason for including a structure in a model is always to replace the momentum euqation with something more suitable for the structure in question.
Most structures may be specified as regular structures, side structures or side structures with reservoirs. Structures without this choice works as regular structure.
Regular
Regular structures are internal structures that specify a flow in the river branch typically based on up- and down- stream conditions.
Side Structure
Side structures let water out of the river network. Internally side structures are handled through generation of a side branch. The side structure will be included, as a regular structure placed midway in the side branch. Head losses are excluded from the flow calculation for side structures. Further for culverts and weirs the assumption of respectively free out- and over- flow is made. The boundary introduced through the inclusion of the side weir is internally specified as a water level boundary with a low water level. The side branch will be called "SideStructure_"<original branch name>"_"<original chainage>. In case of more side structures in the same location these will all be included in the side branch.
Example: Side Structure included in "Branch1" at chainage 1000 meter will effectively be placed in "SS_Branch1_1000meter" in chainage 50 meter. The side branch, "SS_Branch1_1000meter", will have a length of
100 meter.
Side Structure with Reservoir
Including Side Structures with Reservoir in a branch result in automatic generation of a side branch with the structure placed midway. The down stream cross section of the side branch has additional storage area assigned that models the reservoir data specified (ref. section 3.2.2 Processed data, Tabular View). If the reservoir data is specified as Elevationarea the specified values are used directly as additional storage area whereas the additional storage area is derived from relation (x.x) in case of
Elevation-volume specification.
MIKE 11
Tabular view: Structures
Figure 2.19
Structure Plot
The transformation is based on an assumption of both volume and area being 0, 1-meter bellow the lowest specified level.
The boundary introduced through the inclusion of the side weir is internally specified as a no flow boundary. Flow may be included through specification of point source boundaries at the boundary.
More side structures with reservoir in the same location will result in a side branch for each. The side branches will be named "SSPR"<original branch name>"_"<original chainage>"_"<Structure ID>.
Example: Side Structure included in "Branch1" at chainage 1000 meter with ID SideWeir1 will effectively be placed midway in branch
"SSPR_Branch1_1000m_SideWeir1". The length of side branch,
"SSPR_Branch1_1000m_SideWeir", will follow from the position specified if any, otherwise it will be 100 meter.
2.3.2
Structure Plotting
For structures where specification of dimensions and elevations is part of defining the structure, it is possible to make a plot of the structure together
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River Network Editor with the upstream and downstream cross section. This includes all weirs, all culverts, some bridges and most control structures (all except discharge control structures). Plotting structures and their neighbouring cross sections together helps ensuring that structure dimensions and elevations are specified correctly. A typical source of model instability is a structure which is larger or lower than the neighbouring cross section.
For structures which can be plotted the structure dialog contains a section named “Graphic” with a “Plot...” button. Clicking this will open a separate graphical window showing two plots. The upper plot being the upstream cross section and the structure, and the lower plot being the downstream cross section and the structure. Initially, the centre of the structure is horizontally aligned to marker 2 of the cross section.
Clicking the right-mouse button in the graphical view the user will be given the following options in addition to the regular zoom and pan options: z z
Settings...: This will open a separate dialog where the graphical properties of cross section, structure etc. can be changed.
Use same axis scaling U/S and D/S: Selecting this the two plots will be shown with the same scaling of vertical and horizontal axis z
Show next: The next structure (according to the list in the tabular view) neighbouring cross sections will be shown instead of the current.
z z z
Show previous: The previous structure (according to the list in the tabular view) neighbouring cross sections will be shown instead of the current.
Pan structure left: The structure will be moved to the left in the graphical view.
Pan structure right: The structure will be moved to the right in the graphical view z z
Increase pan step: The distance by which the structure moves left/right is increased by a factor 2.
Decrease pan step: The distance by which the structure moves left/right is decreased by a factor 2.
The following figure shows a typical structure plot for a weir.
MIKE 11
Tabular view: Structures
2.3.3
Weirs
River Network Editor
Figure 2.20
The weir property page.
Location
– River Name: Name of the river branch in which the weir is located.
– Chainage: Chainage at which the weir is located.
– ID: String identification of the weir. It is used to identify the weir if there are multiple structures at the same location. It is recommended always to give the weir an ID.
– Type: The lcation type may be Regular, Side Structure or Side
Structure + Reservoir. See section 2.3 Tabular view: Structures for details
Attributes
– Type:
Broad Crested Weir: The calculation of Q/h relations assumes
critical flow at the crest.
Special Weir: The Q/h relationship table must be specified.
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River Network Editor
Weir Formula 1: A standard weir expression is applied. See the
Reference Manual, unedr weir formula.
Weir Formula 2 (Honma): The Honma weir expression is applied.
See the Reference Manual, Weir Formula 2 (Honma).
– Valve:
None: No valve regulation applies.
Only Positive Flow: Only positive flow is allowed, i.e. whenever
the water level downstream is higher than upstream the flow through the structure will be zero.
Only Negative Flow: Only negative flow is allowed, i.e. whenever
the water level upstream is higher than downstream the flow through the structure will be zero.
Head Loss Factors
The factors determining the energy loss occurring for flow through hydraulic structures (only broad crested weir and special weir).
Geometry
Only broad crested weir and special weir.
Type:
– Level-Width: The weir geometry is specified as a level/width table relative to the datum.
– Cross Section DB: The weir geometry is specified in the cross section editor. A cross section with a matching branch name, Topo ID and chainage must exist in the applied cross section file. The Topo
ID is assumed to be the same as that specified in the Branches Property page, see Topo ID (p. 43).
Datum: Offset which is added to the level column in the level/width
table.
Level/Width: Weir shape defined as levels and corresponding flow
widths. Values in the levels column must be increasing.
MIKE 11
Tabular view: Structures
Weir formula Parameters (only weir formula 1)
River Network Editor
Figure 2.21
The weir property page, formula 1.
Width: Width of the flow.
Height: Weir height. See Figure 2.23
Weir Coeff.: Multiplication coefficient in the weir formula.
Weir Exp.: Exponential coefficient in the weir formula.
Invert Level: Bottom datum level. See Figure 2.23
57
River Network Editor
Weir formula 2 Parameters (only weir formula 2 (Honma))
Figure 2.22
The weir property page, formula 2.
Weir coefficient (C1): Multiplication coefficient in the Honma weir
formula.
Weir width: Width of the flow.
Weir crest level: Weir level. See Figure 2.23
58
Figure 2.23
Definition sketch for Weir formula.
MIKE 11
Tabular view: Structures
Weir formula 3 Parameters (only weir formula 2 (Honma))
When choosing weir formula 3 a separate dialog can be opened by clicking the “Details...” button. See the following figure:
River Network Editor
Figure 2.24
Using weir formula 3 several parameters are to be specified for calculation of the flow in three regimes: perfect, imperfect and submerged overflow.
MIKE 11 does not check if there is a continuous transition from one flow regime to the next. This has to be ensured by the user through proper selection of the parameters.
Free Overflow Q/h-relations (only broad crested weir and special weir)
– Broad crested weir: The Q/h relations are calculated using the
Calculate button after all relevant information has been entered.
The result of the calculation will appear in the table. In order to compute the Q/h relation, the nearest upstream and downstream cross section are used. The cross sections must be within the dis-
tance maximum dx (Maximum dx (p. 44)) defined for the branch in
question. The Q/h relation can not be calculated unless the cross sections are defined. It is also necessary that the Simulation File is open in order to load the cross section data from a cross section file.
59
River Network Editor
2.3.4
Culverts
– Special weir: Unlike a broad crested weir, the user must specify
Q/h relations corresponding to free overflow conditions. These must be specified for both positive and negative flows.
Note that Q/h relations must be recalculated if any changes are made to
the weir or the cross sections up- or downstream have been altered. Further, since a weir in MIKE 11 is defined as a structure causing a contraction loss and subsequently an expansion loss, some constraints are placed on the geometry of a broad crested weir. The geometry of the weir must be such that the cross sectional area at the weir is less than the cross sectional area at both the upstream and the downstream cross section for all water levels!
60
Figure 2.25
Culvert editor page.
Branch name
River Name: Name of the river branch in which the weir is located.
Chainage: Chainage at which the weir is located.
MIKE 11
Tabular view: Structures
ID: String identification of the culvert. It is used to identify the culvert
if there are multiple structures at the same location. It is recommended always to give the culvert an ID.
Type: The lcation type may be Regular, Side Structure or Side Struc-
ture + Reservoir. See section 2.3 Tabular view: Structures for details
Attributes
Upstream Invert: Invert level upstream of the culvert.
Downstr. Invert: Invert level downstream of the culvert.
Length: Length of the culvert.
Manning’s n: Manning’s bed resistance number along the culvert.
No. of Culverts: Number of culvert cells.
Valve Regulation:
– None: No valve regulation applies.
– Only Positive Flow: Only positive flow is allowed, i.e. whenever the water level downstream is higher than upstream the flow through the structure will be zero.
– Only Negative Flow: Only negative flow is allowed, i.e. whenever the water level upstream is higher than downstream the flow through the structure will be zero.
Section Type: Closed or Open.
Head Loss Factors
The factors determining the energy loss occurring for flow through hydraulic structures.
Geometry
The cross sectional geometry of a culvert can be specified as:
– Rectangular: The width and height specify the geometry.
– Circular: The geometry is specified by the diameter.
– Irregular Level-Width Table: The geometry is specified using a level/width table. Values in the level column must be increasing.
– Irregular Depth-Width Table: The geometry is specified using a depth/width table. Values in the width column must be increasing.
River Network Editor
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River Network Editor
– Section DB: The geometry is specified by a cross section. A cross section with the same branch name, Topo ID and chainage must exist in the cross section file. The Topo ID is assumed to be the
same as specified in Topo ID (p. 43).
Flow Conditions
Once the above parameters and the desired number of Q/h relations have been filled in the button Calculate Q/h relations can be pressed. The result of the calculation will appear in the table. If any of the parameters defining the culvert is changed the user should remember to re-calculate the Q/h relations. In order to compute the Q/h relation, the nearest upstream and downstream cross section are used. The cross sections must be within the
distance maximum dx (Maximum dx (p. 44)) defined for the branch in
question. The Q/h relation can not be calculated unless the cross sections are defined. It is also necessary that the Simulation File is open in order to load the cross section data from a cross section file.
The Q/h relations are given as Q/y relations (where y is depth above invert).
The Q/y relations table also shows the type of flow occurring. The possible types are:
– No Flow: No flow occurs at the first level (y = 0) and when the valve regulation flag prohibits flow in one direction
– Inlet C: The flow at the inlet is critical
– Outlet C: The flow at the outlet is critical. A backwater curve using a fine resolution is calculated to relate the discharge to the upstream water level in the river
– Orifice: The flow at the culvert inlet has an orifice type formation.
The discharge is based on the orifice coefficients shown in the menu. These coefficients can be edited, added or deleted, if required. The Q/h relations will be re-calculated after editing the coefficients
– Full Cul: The culvert is fully wet with a free discharge at the outlet.
Note that Q/h relations must be recalculated if any changes are made to
the culverts defining parameters or if the cross sections up- or downstream have been altered. Further note that since a culvert in MIKE 11 is defined as a structure causing a contraction loss, a friction loss (bend loss) and subsequently an expansion loss some constrains are placed on the geometry of a culvert. The geometry of the culvert must be such that the cross sectional area at the inflow is less than the cross sectional upstream of the
MIKE 11
Tabular view: Structures culvert for all water levels. Similarly the cross sectional area at the outflow end must be less than the cross sectional immediately downstream of the culvert.
2.3.5
Pumps
River Network Editor
Figure 2.26
The pump property page.
Both pumps operating internally in the river system and pumps with external outlet are included in MIKE11. Pumps with internal outlet increases the local water level whereas pumps with external outlet removes water from the river system.
Location
– Branch Name: Name of the river branch in which the pump is located.
– Chainage: Chainage at which the pump is located.
– ID: String identification of the pump. Used for identification of the pump in case of multiple structures at the same location. Specification of pump ID is recommended.
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64
River Network Editor
– Type: The lcation type may be Regular, Side Structure or Side
Structure + Reservoir. See section 2.3 Tabular view: Structures for details
Control Parameters
– Start Level: Water level at the inflow that activates the pump.Note that for pumps with internal outlet the inflow is situated at the previous h-point (previous with regard to chainage) in case of positive discharge and at the next h-point with regard to chainage) in case of negative discharge. The sign of the discharge follows from the specifications made under Pump Data.
– Stop Level: Water level at which the pump starts closing down.
– Start-up Period: Period for changing pump discharge from zero to full. The pump discharge is changed linearly in time.
– Close Down Period: Period for changing pump discharge from full to zero. The pump discharge is changed linearly in time.
Pump Data
– Outlet:
Internal: Water is pumped internally in the river branch.
External: Water is pumped out of the river branch.
– Specification Type:
Fixed Discharge: Pump rate independent of the local water head expect for the start/stop control.
Tabulated Characteristic: Pump rate controlled by specified characteristic (Q-dH-curve) and the water level difference between upstream water level and outlet level/downstream water level.
– Discharge: Pump rate when applying "Fixed Discharge".
– Outlet Level: Level of pump outlet. The outlet may be submerged or free. Relevant only in case of "Tabulated Characteristic".
– Q-dH-curve: Q-dH-characteristic of the pump. The discharge is determined through interpolated look up in the table specified. The dH used for the look-up is given as the difference between up- and down- stream water level in case of submerged outlet and as the difference between upstream level and outlet level in case of free outlet. The shift between the two is fully dynamic allowing an outlet to change from being free to submerged and vice versa.
MIKE 11
Tabular view: Structures
Figure 2.27
Q-dH curves for pumps.
Note that MIKE11 does not allow extrapolation. It is therefore recom-
mended to add limit points to the Q-dH -curve. See figure.
Note also, that the applied Q sign in the "Discharge"- or "Q-dH-curve"-
fields controls the pump direction (with or against chainage).
2.3.6
Bridges
MIKE 11 offers a number of approaches when modelling flow through bridges. The approach to choose should be based on the assumptions for the different methods and the requirements of the modelling.
The bridge modelling approaches can be divided into pure free flow methods and methods which may be combined with submergence/overflow methods. The pure free flow methods can be further sub-divided into methods for piers and methods for arches.
The methods specially designed for piers are z z
Bridge piers (Nagler): An orifice type of flow description with the effect of the piers taken into account through an adjustment factor.
Bridge Piers (Yarnell): An equation derived from experiments for normal flow conditions in the sub critical flow range. Again the effect of piers is handled through the use of adjustment factors.
The free flow arch methods available are
River Network Editor
65
66
River Network Editor z
Arch bridges (Biery and Delleur): An orifice type of equation is used to describe the discharge through the bridge. The equation is derived under the assumption of a rectangular channel and is based on a single span arch opening. Multiple arch openings are handled by a simple multiplication factor.
z
Arch bridges (Hydraulic research method, HR): The HR method is based on laboratory experiments of both single and multi spanned arch bridges in rectangular channels. The method uses tables describing the relation between the blockage ratio, the downstream Froude number and the upstream water level.
The methods that can be combined with both submergence and overflow methods are the following z z
Energy Equation: A standard step method where a backwater surface profile is determination is used to calculate the discharge through the bridge. The method takes the contraction and expansion loss for bridges of arbitrary shape into account. The method assumes sub-critical flow and may default to critical flow for steep water surface gradients.
Federal Highway Administration (FHWA) WSPRO method: The
FHWA WSPRO method is based on the solution of the energy equation. Contraction loss is taken into account through the calculation of an effective flow length. Expansion losses are determined through the use of numerous experimentally based tables. The method takes the effect of eccentricity, skewness, wingwalls, embankment slope etc. into account through the use of these tables.
z
US Bureau of Public Roads (USBPR) method: The USBPR method estimates free-surface flow assuming normal depth conditions. the method is based on experiments and takes the effect of eccentricity, skewness and piers into account.
The submergence methods available are z z
Pressure Flow using the Federal Highway Administration method:
Two orifice equation descriptions are used. One for situations when the orifice is submerged downstream and modified equation for situations when only the upstream part of the orifice is submerged.
MIKE 11 culvert: A standard MIKE 11 culvert description may be chosen for submergence flow. The culvert to be used is specified by the user. The culvert is only active if submergence occurs.
MIKE 11
Tabular view: Structures z
Energy equation: The flow under the bridge is determined through a standard backwater step method. The flow is assumed to be in the subcritical range and thus the method may default to critical flow. Both contraction and expansion loss is taken into account.
Overflow methods available are: z z
Energy Equation: The flow over the bridge is determined through a standard backwater step method. The flow is assumed to be in the subcritical range and thus the method may default to critical flow. Both contraction and expansion loss is taken into account.
Road overflow using the Federal Highway Administration method:
The overflow is modelled using a weir equation taking tail water submergence into account through the use of a submergence coefficient.
The method may be used for both gravel and paved surfaces.
z
MIKE 11 weir: A standard MIKE 11 weir description may be chosen for overflow. The weir to be used is specified by the user. The weir is only active if overflow occurs.
Finally there are two additional bridge types which are not pre-processed prior to the simulation. These bridge types form part of a separate module.
z
Bridge Piers (D’Aubuisson): The discharge is determined based on a momentum equation assuming no bed slope and that the friction loss is negligible. The method can handle pure rectangular channel descriptions but also gives the option of using cross sections of arbitrary shape.
z
Fully submerged bridges: The fully submerged takes the drag of the fully submerged bridge into account. Friction is neglected and the bed is assumed horizontal through the bridge.
Also note that the use of the two bridge types Fully submerged bridge and
Bridge piers (D’Aubuisson’s formula) requires the installation of a separate module.
Overflow is only available in combination with submerged flow. When the bridge structure bottom level is exceeded the bridge type solution will be ignored and replaced with a submerged solution. When the bridge structure top level is exceeded the submerged solution is combined with overflow.
For all bridges there are some common settings consisting of:
River Network Editor
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River Network Editor
– Name: The river name. Used along with the chainage to identify the location of the bridge in the network. River name and branch name are identical,
– Chainage: The location of the bridge in the river. The river cannot be located at a location where a cross section exists.
– Bridge ID: String identification of the bridge. The string identification for the bridge is used in the output, but also for the preprocessing of the bridges. It is important that every bridge in the set-up has a unique non-empty Bridge ID. The latter ensures that bridges can be uniquely identified by the calculation kernel of MIKE 11.
– Method: Pull down menu for selecting the free flow method used in calculating the flow through the bridge. The methods are briefly described above. Please refer to the reference manual for a more thorough decsription of the underlying assumptions and governing equations.
– Options: Some of the bridge methods offer a number of additional options. These options may include e.g. piers, skewness etc. To include an option simply select the appropriate box.
– Geometry and Loss factors: Thorugh the use of the Edit button the user can access the interface for for entering geometric and loss factor parameters. The Detail button gives access to the edit and or review of the tables used for determining loss coefficients.
– Graphic: Not available in present release.
– Submergence: (Pressure flow) Available if the Submergence checkbox is marked (See Options). The user must select one of the methods: Energy Equation, FHWA WSPRO or MIKE 11 culvert.
For details on FHWA WSPRO see Submergence, FHWA WSPRO.
For a description of culverts please refer to the appropriate section
(2.3.4). The energy equation method is equivalent to the one used
for free surface flow. Note that only some methods allow the submergence option.
– Culvert no: When choosing a MIKE 11 culvert details of the cul-
vert structure are in the culvert menu (See section 2.3.4). Culvert no
is chosen as the number marked in the overview box in the culvert menu.
– Bridge level (bottom): The bottom level of the bridge. The geometry of the lower part of the bridge consists of the data in bridge cross sections combined with the bridge level bottom.
MIKE 11
Tabular view: Structures
– Overflow: Note that the overflow option is only available if the submergence option is also seleceted. The choices are FHWA
WSPRO, Energy Equation or MIKE 11 weir method. For details on
FHWA WSPRO see Overflow, FHWA WSPRO. If the Energy
equation method is selected the user needs to supply the bridge level at the top of the bridge. This level indicates the lowest point on the deck. The data in the supplied for the bridge geometry also constitutes part of the geometry of the overflow part.
– Weir no: If a MIKE 11 weir is chosen the appropriate weir from the
weir menu must be selected (See section 2.3.3). Weir no is chosen
as the number marked in the overview box in the weir menu.
River Network Editor
Figure 2.28
Overview, Branch2 has three bridge openings - 2, 3 and 4. Marked in the right part of the overview window.
The overview is split in two. The left hand side gives an overview of the physical bridges in the set-up and the right the different openings. If a bridge consists of one opening there will be one entry on the left and one on the right for that particular bridge. If a bridge has multiple openings there will only be one entry on the left for that particular bridge and a number of entries on the right corresponding to the number of openings in the bridge.
69
70
River Network Editor
To add a bridge to a set-up simply place the cursor in the filed of the last bridge and hit the TAB key until a new line appears. Similarly for additional openings in the same bridge. As an alternative the insert key on the keyboard may be used. To sumarize the layout:
– Overview: Left part shows River name, Chainage and Bridge ID.
Right part show methods for the bridge openings.
– Multiple waterway openings: If working with multiple waterway openings all multiple waterway openings are marked when the
bridge is activated. (See Figure 2.28). In order to add additional
openings, mark a row in the right part of the overview window and press insert on the keyboard.
Working with Loss factor tables:
Some of the bridge methods require values found in tables. These tables can either be used based on default values taken from the literature or may be user defined/edited. In general it is recomended to use the default values.
The loss / adjustment factor tables are viewed by pressing the Details button. The default loss factor tables are generated by pressing the Edit button.
When having default unmarked for a loss factor changes in the loss factor table will be saved. If default is marked changes will not be saved after pressing edit.
In the loss factor tables the user can create more columns and rows. Placing the cursor in the last column (right end) and pressing the arrow button on the keyboard will create a new column. Pressing the tab button on the keyboard when having the cursor in last bottom cell creates an additional line.
federal highway Administration (FHWA) WSPRO & US bureau of Public Roads (USPBR) Bridge
The FHWA WSPRO, Energy Equation and the USPBR methods may be used to describe free surface flow through a bridge opening. The methods use the up and down stream cross sections located in the cross section editor, aswell as two additonal cross ections to be defined within the network editor.
The location of the cross sections outside the bridge should be so that any potential contraction or expansion loss is taken into account. In other words the optimal location is where the stream lines are parallel prior to a
MIKE 11
Tabular view: Structures contraction and post a possible expansion. As a rule of thumb the distance between the bridge and the cross sections should be of the order one open-
River Network Editor
Figure 2.29
Location of up- and downstream cross section. 1: Upstream river cross section. Defined in the cross section editor. 2: Upstream bridge cross section. Defined in the network editor, bridge geometry.
3: Downstream bridge cross section. Defined in the network editor, bridge geometry. 4: Downstream river cross section. Defined in the cross section editor.
Available options for FHWA WSPRO Bridge:
– Submergence
– Overflow
– Skewness, Used when the embankments is not perpendicular to the approaching flow.
– Eccentricity, Used when the bridge opening is eccentrically located in the river.
– Multiple waterway opening
– Asymmetric opening, Used for individual definition of left and right abutments.
– Spur dykes
– Piers/piles
Available options for USBPR Bridge:
– Submergence
71
River Network Editor
– Overflow
– Skewness, Used when the embankments is not perpendicular to the approaching flow.
– Eccentricity, Used when the bridge opening is eccentrically located in the river.
– Multiple waterway opening
– Piers/piles
Geometry and loss factors are viewed by pressing the Edit button under
Geometry and Loss factors.
Geometry, Waterway opening:
72
Figure 2.30
Geometry property page.
– Opening type: (see definition sketch Figure 2.31 - Figure 2.34).
Only used for the FHWA WSPRO method.
– Embankment slope: Only for FHWA WSPRO, opening type II,
III, and IV. Example, insert 2 for a 1:2 slope.
– Waterway length L
MIKE 11
Tabular view: Structures
– At level z: Only for FHWA WSPRO, opening type II, III, and IV.
Enter the level which corresponds to the minimum waterway length, typically the soffit level.
Figure 2.31
Definition sketch of type I opening, vertical embankments and vertical abutments, with or without wingwalls (after Matthai).
Figure 2.32
Definition sketch of type II opening, sloping embankments without wingwalls (after Matthai).
River Network Editor
Figure 2.33
Definition sketch of type III opening, sloping embankments and sloping abutments (spillthrough) (after Matthai).
73
74
River Network Editor
Figure 2.34
Definition sketch of type IV opening, sloping embankments and vertical abutments with wingwalls (after Matthai).
Geometry, Cross-section table:
– Slope: If the slope check box is marked the only the upstream bridge cross section must be defined. The downstream cross section is generated be copying the upstream cross section and adding the slope defined in the slope edit box. Upstream bridge cross section correspond to section 2 and downstream bridge cross section corre-
spond to section 3. (See Figure 2.29).
– Datum: The water level datum is added to the Z values in the Cross section table.
– X: Horizontal values for the cross section. Note that the x-values are evaluated with the up and downstream cross section. As a result
it is important that the four cross sections (See Figure 2.29) are
placed correct in respect to the x-values.
– Z: Vertical level of the cross section point.
– Resistance: Additional resistance in the cross section point. 1 is resistance corresponding to the manning number.
– Marker: Define the abutments (See Figure 2.35).
MIKE 11
Tabular view: Structures
River Network Editor
Figure 2.35
Definition of the bridge cross section markers.
Geometry, Multiple waterway opening:
Geometry and loss factors are defined for each opening when working
with multiple waterway openings (see Figure 2.28). The position of each
opening and the corresponding stagnation points are defined from the stagnation point value (if not default) and from the horizontal values in the
bridge cross sections. (See Figure 2.36)
– Use default left stagnation points: When the checkbox is marked the stagnation point is set by MIKE 11. When the checkbox is unmarked the user must define the left up and down stream stagnation points in the edit boxes.
– Left stagnation point upstream: Horizontal value (X value) for the left stagnation point in the upstream river cross section defined
in the cross section editor. Section 1 in Figure 2.29. The stagnation
point to the right is found from the neighbouring opening. The left stagnation point refers to a lower value of X than the right stagnation point.
– Left stagnation point downstream: Horizontal value (X value) for the left stagnation point in the downstream river cross section
defined in the cross section editor. Section 4 in Figure 2.29. The
stagnation point to the right is found from the neighbouring opening. The left stagnation point refers to a lower value of X than the right stagnation point.
75
River Network Editor
Figure 2.36
Multiple openings and stagnation points.
Loss factor:
76
Figure 2.37
Loss factor property page
MIKE 11
Tabular view: Structures
– Entrance rounding: Loss factor for FHWA WSPRO, opening type
I. When ’use default’ is ticked a default loss factor table will be generated from the information entered under entrance rounding.
Corner type: Enter the radius, r for the corner rounding. Wingwall type: enter the width, W and angle of the wingwall.
River Network Editor
– Spur dykes: FHWA WSPRO, Loss factor when spur dykes is marked in options. When, use default, a default loss factor table will be generated. For Straight spur dykes the user must enter length and offset from the bridge opening. For Elliptical spur dykes the user must enter length and angle.
– Wingwall: Loss factor for FHWA WSPRO, opening type IV. When, use default, a default loss factor table will be generated from the entered wingwall.angle.
– Froude number: Loss factor for FHWA WSPRO, opening type I.
When, use default, a default loss factor table will be generated.
– Base Coefficient: Loss factor for FHWA WSPRO, opening type I,
II, III and IV and USBPR. When, use default, a default loss factor table will be generated. For the USBPR method an opening type is chosen.
– Abutment: Loss factor for FHWA WSPRO, opening type III.
When, use default, a default loss factor table will be generated.
– Average Depth: Loss factor for FHWA WSPRO, opening type II.
When, use default, a default loss factor table will be generated.
– Velocity distribution coefficient: Loss factor for the USBPR method. When, use default, a default loss factor table will be generated.
– Piers / Piles: Loss factor when ’piers / piles’ is marked in options.
When, use default, a default loss factor table will be generated.
Choose Type (piers or piles) and enter the proportion of waterway blocked by piers/piles. For the USBPR method the user must choose a piers type for generating a default loss factor table.
77
78
River Network Editor
– Eccentricity: Loss factor when eccentricity is marked in options.
When, use default, a default loss factor table will be generated.
– Skewness: When skewness is marked in options an angle for skewness is entered in the edit box, Skewness angle,.
– Resistance: Choose Manning M or n as the unit for resistance.
– Resistance value: The value for resistance on the bridge structure
between markers 1 and 4 and between 5 and 3 (see Figure 2.35).
Between markers 4 and 5 the bed resistance given in the HD editor will be used.
Table 2.1
Loss factor tables for FHWA WSPRO
Table
Base coefficient
Base coefficient
C
′
C
′
Froude number
k
F
Entrance
k
Average depth
k y
Abutment
k x
Wingwall
k
θ
Eccentricity
k e
Piers
k j
I
I
Opening
Type
II, III and IV
I
II
III
IV
I, II, III and
IV
I, II, III and
IV
Function of:
e m m
F
3
m m
or
M
(
Y a
+
Y b m
or
M m
or
M
or
or
M
Piles #1
Piles #1
Piles #2
Spur dike
k j
= 0,1
k j
= 0,1
k j k d
,
k
I
m
or
M
II, III and IV
m
or
I, II, III and
IV
k j
= 0,1
I, II and IV
m
or
M
MIKE 11
Tabular view: Structures
Table 2.1
Spur dike #1
Spur dike #2
Spur dike #2
Loss factor tables for FHWA WSPRO k d k a k b
III
m
or
M L d
⁄
b
III, Elliptical
m
or
M L d
⁄
b
III, Straight
m
or
M
In the Loss Factor menu the user can choose to use
m
or as axis in the tables.
Where:
m
Channel contraction ratio.
Bridge opening ratio.
j
M
L
Bridge waterway flow length.
Bridge opening length.
b
F
3
Froude number in downstream bridge section.
(
Y a
+
Y b
Average water level in bridge section.
x
Unwetted abutment length.
e
Eccentricity.
L d
Portion of waterway blocked by piers/piles.
Spur dike length
Table 2.2
Eccentricity
Skewness
Piers
Loss factor tables for USBPR
Table
Base coefficient
Velocity distribution coefficient
k
α
2
e
∆
k
∆
k
Function of:
M
or
m
M
or
m
α
1
M
M
or
m
∆
k
M
or
m
River Network Editor
79
80
River Network Editor
In the Loss Factor menu the user can choose to use
m
or as axis in the tables.
Where:
M
Bridge opening ratio.
Channel contraction ratio.
m e
Degree of eccentricity.
α
1
Velocity distribution coefficient in upstream cross-section.
Fully Submerged Bridge
Press the Edit button under Geometry and Loss factors.
The details of the bridge geometry and location are inserted in the appropriate boxes:
– Channel width: The user specified channel width. If a positive value is implemented the water level increment calculation are based on a rectangular channel analysis. If a negative value is implemented a more general momentum equation is solved utilising the cross sections upstream and downstream of the bridge.
– Section area of submerged bridge: The cross sectional area of the submerged bridge. Note that since the bridge formula assumes that the bridge is fully submerged
– Drag coefficient: The drag coefficient of the bridge.
Figure 2.38 shows an example where a submerged bridge is inserted at the
chainage 500 m in the river ‘RIVER 1’. The channel width is specified as
10 m, the section area of the bridge is set equal to 5 m and the drag coefficient is set to 1.6.
MIKE 11
Tabular view: Structures
Figure 2.38
Submerged bridge geometry property page.
Note: If the Froude number downstream of the fully submerged bridge is
greater than the criteria (default 0.6) the effect of the bridge is ignored.
The criteria value may be changed in the Mike11.ini file by setting the variable:
BRIDGE_FROUDE_CRITERIA.
Arch Bridge (Biery and Delleur) & (Hydraulic Research (HR))
The Arch Bridge methods describe free surface flow through one or more arch bridge openings.
Since the equations used for arch bridges are only valid for free flow submergence and and overflow cannot be selected. Geometry and loss factors are viewed by pressing the Edit button under Geometry and Loss factors.
River Network Editor
Figure 2.39
Arch Bridge Geometry property page.
81
River Network Editor
Figure 2.40
Arch Bridge Loss factor property page.
– Opening width, b: Opening width at the Arch spring line.
– Number of arches: The number of arch openings in the bridge.
– Level for bottom of arch curvature: Vertical level for Arch spring line.
– Level for top of arch curvature: Vertical level upper most point in the arch.
– Radius of arch curvature, r.
– Coefficient of discharge, Use default: When, use default, a default loss factor table will be generated.
82
Figure 2.41
Hydraulic variables for Arch Bridge.
Loss factor tables for arch bridges:
Biery and Delleur: Coefficient of discharge,
C
D
is a function of or
MIKE 11
Tabular view: Structures
HR: Backwater ratio
H
1
⁄
Y
4
Bridge piers (D’Aubuisson’s formula)
Press the Edit button under Geometry and Loss factors.
The details of the bridge geometry and location are inserted in the appropriate boxes:
– C constant: User specified constant (< 1).
– Channel width upstream of piers: If the width is positive the water level increment due to the bridge is calculated on the basis of a rectangular channel analysis. If a negative value is given the calculation is based on the cross sections upstream and downstream of the bridge.
– Total width of piers.
Figure 2.42 shows an example with bridge piers inserted at the chainage
500 m in the river ‘RIVER 1’. The bridge piers have been given the topological identification tag ‘Bridge 1’. The geometry dependent non-dimensional constant has been given the value 0.8, the upstream width is specified as 10 m and the total width of the piers is set to 3.5 m.
River Network Editor
Figure 2.42
D’Aubuisson Bridge piers geometry property page
Note: If the Froude number downstream of the piers is greater than the cri-
teria (default 0.6) the effect of bridge piers using D’Aubuisson’s formula is ignored. The criteria value may be changed in the Mike11.ini file by setting the variable:
83
River Network Editor
BRIDGE_FROUDE_CRITERIA.
Bridge piers (Nagler) & (Yarnell)
The Nagler and Yarnell methods describes free surface flow trough a bridge opening with piers.
Available options for Nagler and Yarnell:
– Submergence
– Overflow
Geometry and loss factors are viewed by pressing the Edit button under
Geometry and Loss factors.
Figure 2.43
Nagler and Yarnell Bridge piers geometry property page.
84
Figure 2.44
Nagler and Yarnell Bridge piers Loss factor property page.
– Opening width, b: The total opening width between the piers.
MIKE 11
Tabular view: Structures
– Coefficient of discharge, Use default: When, use default, a default loss factor table will be generated.
– Type of piers: When, use default, marked choose Type of piers.
Loss factor tables for piers bridges:
Submergence, FHWA WSPRO
The method describes pressure flow through a submerged bridge and is used in combination with one of the methods describing free-surface flow.
Submergence is available if the Submergence check box is marked (see
Options) and FHWA WSPRO is selected in the Submergence box.
Figure 2.45
Submergence, FHWA WSPRO, property page.
– Bridge level (bottom): Vertical level of the bottom of the girders.
– Use default: When use default a default loss factor table will be generated.
– Details: Loss factor tables are viewed by pressing the Details button. The loss factor table is only of interest if orifice flow is set to
ON in the MIKE11.ini file. Orifice flow is in general not recommended.
Overflow, FHWA WSPRO
The method describes weir flow bridge and is used in combination with submerged flow. Overflow is available if the Overflow check box is marked (see Options) and FHWA WSPRO is selected in the Overflow box.
River Network Editor
85
86
River Network Editor
Figure 2.46
Overflow, FHWA WSPRO, property page.
– Bridge level (top): Vertical level of the road.
– Length: Width of top of embankment in the direction of flow.
– Discharge, Use default: When use default a default loss factor table will be generated.
– Surface: When Use default marked, choose a surface type for generating default loss factor tables.
– Details: Loss factor tables are viewed by pressing the Details button.
Loss factor tables for road overflow: waterway length
L
R
for
h s
⁄
L
R
>
0,15
.
h s
⁄
L
R
≥
0,15
.
MIKE 11
Tabular view: Structures
2.3.7
Regulating
River Network Editor
Figure 2.47
Regulating structure property page.
This structure type is applied where discharge through a dam is to be regulated as a function of the water level, and the inflow into the reservoir.
The Regulating property page is used for defining a regulating structure such as a pump. The property page consists of a number of dialog boxes
(see Figure 2.47) whose functionality is described below:
Location and Type
River Name: Name of the river branch in which the weir is located.
Chainage: Chainage at which the weir is located.
Type:
– Function of Time: The discharge through the structure is specified as a function of time. The actual discharge time series must be spec-
ified in the Boundary Editor (p. 193).
– Function of h and/or Q: The discharge through the structure is defined as a function of h or Q at two locations (J1 and J2) in the river model: Q = f(J2) .
J1
87
River Network Editor
ID: String identification of the structure. It is used to identify the struc-
ture if there are multiple structures at the same location. It is recommended always to give the structure an ID.
Structure Type: The lcation type may be Regular, Side Structure or
Side Structure + Reservoir. See section 2.3 Tabular view: Structures for details
Location and Type of Control Point
This section is only available when the regulation is specified as a h/Q function. The locations J1 and the J2 are specified in terms of branch name and chainage. In addition the user must specify J1 and J2 as being an h- or a Q-point.
Regulation Function
This section is only available when the regulation is specified as a h/Q function. The function f(J2) is specified in the Regulation Function table as a series of factors for corresponding values of J2.
Note that a regulating structure may be used for implementing an internal
Q/h-relation. This is done by choosing the J2 point as the h-point upstream of the structure and letting the function f(J2) describe the required Q/hrelation. Finally a dummy branch must be included in the set-up. This dummy branch should be constructed so that a unit discharge flows through it. The J1 point is then simply chosen as a Q-point in the dummy branch.
2.3.8
Control Str.
Control structures may be used whenever the flow through a structure is to be regulated by the operation of a movable gate which forms part of the structure.They can also be used to control the flow directly without taking the moveable gate into consideration. In this case it simulates a pump.
88 MIKE 11
Tabular view: Structures
Figure 2.48
The control structure property page.
Location
Branch name: Name of the river branch in which the structure is located.
Chainage: The chainage in which the structure is located.
ID: String identification of the structure. It is used to identify the structure
if there are multiple structures at the same location. It is recommended always to give the structure an ID.
Type: The lcation type may be Regular, Side Structure or Side Structure +
Reservoir. See section 2.3 Tabular view: Structures for details
Attributes
Gate Type
– Overflow: This gate type corresponds to a variable crested weir.
– Underflow: This gate type corresponds to a vertical sluice gate.
– Discharge: This gate type corresponds to a pump.
River Network Editor
89
90
River Network Editor
– Radial gate: This gate type corresponds to a Tainter gate. In contrast to the other gate types a radial gate does not need any information about head loss factors. Instead a number of radial gate
parameters must be entered, see Radial Gate Parameters (p. 91).
– Sluice, Formula: This gate is physically the same as an underflow gate but instead of using the energy equation a set flow formulaes
are applied, see Parameters for gate type = Sluice, formula (p. 93).
Number of gates
The number of identical gates is entered here. This variable is used when a series of identical gates are simulated.
Underflow CC
This is the contraction coefficient used for underflow gates only. Default value is 0.63.
Gate width
The width of the gate. Not applicable for gates of the Discharge type.
Sill level
The level of the sill just upstream of the gate. Not applicable for gates of the Discharge type.
Max. Speed
This variable defines the maximum allowable change in gate level per. time. (If a discharge gate is chosen the variable defines the maximum allowable change in discharge per. time). This variable is introduced because the control strategy defining the variation of the gate level can result in very rapid changes in gate level. This is probably not realistic, further it can create instabilities in the computation.
Initial Value
If the Initial Value checkbox is checked the value specified will be used as initial value
Max Value
If the Max Value checkbox is checked the value specified will interpreted as the highest possible gate level or in case of a discharge structure the highest possible pump discharge.
MIKE 11
Tabular view: Structures
Head loss factors
The factors determining the energy loss occurring for flow through hydraulic structures. Head loss parameters only apply for underflow and overfloe gates.
Radial Gate Parameters
The look of the control structure property page when a radial gate is cho-
River Network Editor
Figure 2.49
The control structure property page when a radial gate has been selected.
In Mike11 radial gates are automatically divided into an underflow part and an overflow part. When specifying gate levels for a radial gate the user should specify the level for the underflow part, i.e. the level of the bottom of the gate. The gate level for the overflow part is then calculated based on geometric considerations.
91
92
River Network Editor
Tune Factor
Discharge calibration factor. This factor is used only on the part of the discharge that flows below the gate. It corresponds to
τ in eqs. (1.81) and
(1.83) in the reference manual.
Height
Height above sill of the overflow crest of the gate when the gate is closed,
Radius
Radius of gate, see Figure 2.50.
Trunnion
Height above sill of centre of gate circle, see Figure 2.50.
Weir Coeff.
Coefficient used when calculating the flow above the gate. Corresponds to
α in eqs. (1.85) and (1.86) in the reference manual.
Weir Exp.
Coefficient used when calculating the flow above the gate. Corresponds to
β in eqs. (1.85) and (1.86) in the reference manual.
Tran. Bottom
Parameter used to define the transition zone between free flow and submerged flow. Corresponds to y
Tran,Bottom
defined in Hydraulic Aspects -
Radial Gates (p. 69) in the reference manual.
Tran. Depth
Parameter used to define the transition zone between free flow and submerged flow. Corresponds to y
Tran,Depth
defined in Hydraulic Aspects -
Radial Gates (p. 69) in the reference manual.
MIKE 11
Tabular view: Structures
Figure 2.50
Definition of a radial gate.
Parameters for gate type = Sluice, formula
When choosing this type of gate a special set of parameters will be requested in the upper right part of the control structure dialog. See the following figure:
River Network Editor
Figure 2.51
Sluice gate parameters.
With this gate type the flow under the gate is divided into four flow regimes the choice of which depends on the upstream and downstream water level. The four flow regimes are:
93
94
River Network Editor
– CS: Controlled Submerged
– CF: Controlled Free
– US: Uncontrolled Submerged
– UF: Uncontrolled Free
Additionally flow over the top of the sluice gate is taken into account when the water level up stream and/or downstream exceeds the gate level plus the gate height.
In short the high limit and low limit parameters are used to smoothen the transitions between fow regimes and coefficient a and exponent b are pararameters for the flow equations. Please refer to the reference manual for further details.
Control Definitions
The way the gate level is calculated is determined by a control strategy. A control strategy describes how the gate level depends on the value of a control point. For a specific gate it is possible to choose between an arbitrary number of control strategies by using a list of ‘if’ statements. For each of these statements it is possible to define an arbitrary number of conditions that all must be evaluated to TRUE if the ‘if’-statement is to be evaluated to TRUE. It is hereby made possible to use different operating policies depending on the actual flow regime, time etc.
From above it is realized that it takes two things to define a control strategy: The conditions that must be fulfilled for the strategy to be executed and the control strategy itself.
The control strategy itself is a relationship between an independent variable (the value of the control point) and a dependent variable (the value of the target point). As an example: Assume that the position of the gate is determined by the downstream water level. The control point is then the grid point downstream of the gate. The value of the water level in this points thus determines the value of the target point which in this example will be the gate level. The reason for using the concept ‘Target Point’ and not just call it gate level is as follows: In Mike11 there are different Calculation Modes. It is hereby made possible both to define control strategies that determines the value of the gate level directly and control strategies that determines the gate level indirectly. Suppose that you want to know how the gate should be operated in order to maintain a certain water level on the upstream side of the gate. The requested upstream water level has a seasonal variation due to a seasonal variation of the flood risk. To do this in Mike11 the control point is the time and the target point is the upstream water level. The way to get from the requested water level to a gate level
MIKE 11
Tabular view: Structures is done by choosing the calculation mode ‘Iterative Solution’. In this case
Mike11 will iterate on the gate level until the upstream water level equals the requested value (or acceptable close to this value).
Five main parameters must be defined: Priority, Calculation Mode, Control Type, Target Type and Type of Scaling. Further some more details must be defined. We start with a description of the main parameters. As
seen in Figure 2.48 or Figure 2.49 the control definitions section consists
of a table. Each line in this table represents the main parameters of an ‘if’statement.
Priority
As mentioned under Control Definitions (p. 94) it is possible to make
Mike11 choose between an arbitrary number of control strategies. These control strategies are organised using a list of ‘if’ statements. The control strategy belonging to the first of these statements that are evaluated to
TRUE will be executed. It is thus of importance for the user to define which ‘if’-statement that are evaluated first, second, third and so on. This is enabled by the priority field. In this the user defines the priority of the
‘if’-statement by writing an integer number. By default the first line in the table will have priority equal to one, the second line will have priority equal to two and so on. Note that the ‘if’-statement with the lowest priority always will be evaluated to TRUE. This is because this statement is connected to the default control strategy that will be executed when all other ‘if’-statements are evaluated to FALSE.
Calculation Mode
– Tabulated: This is the default calculation mode, which determines the value of the gate level directly (gate discharge in case of a discharge gate).
– PID operation: This calculation mode corresponds to a PID operated gate. With this calculation mode the gate level is determined indirectly using the following equation:
u n
=
α
1
K 1
+
T s i
+
T s d
{
y n ref
–
y n
}
–
α
2
K 1 2
T d s
{
y
–
ref
–
y
}
–
α
3
K
T d s
–
ref
–
y
}
–
u
(2.1) where u
n
is the gate level (or discharge in case of a discharge structure) at the nth time step, K a factor of proportionality, T gration time, T
d
the derivation time, T
i
the inte-
s
the sampling period, i.e. the
River Network Editor
95
96
River Network Editor simulation time step,
y n ref
is the required value of the target point at the nth time step, y
n
the actual value of the target point at the nth time step,
α
1
,
α
2
,
α
3
are weighing factors. In this way {y
ref
- y} represents a deviation from the desired situation. This deviation is min-
imized by the PID algorithm in (2.1).
The variables K, T
d
, T
i
,
α
1
,
α
2
and
α
3
are entered by the user, see
Iteration / PID (p. 110). The rest is calculated by Mike11.
– Momentum equation: If ‘Momentum equation’ is chosen the flow through the structure will be calculated using the momentum equation instead of the energy equation. This corresponds to ignoring the presence of the structure. Because of this no calculation of gate level/discharge will take place. Therefore specification of control point, target point and scale factor has no importance when choosing calculation mode as ‘Momentum equation’. An example where this calculation mode could be useful is in a river with an inflatable dam.
– Iterative solution: This calculation modes gives an indirect deter-
mination of the gate level/discharge. In Control Definitions (p. 94) a
small example was given explaining how this calculation mode could become useful. When using this calculation mode the user must take great care when choosing the target points. This is because the iteration takes place for a fixed time step. If the target point is placed too far away from the gate the changes in gate level during the iterative procedure will not have any effect on the value of the target point The parameters that the user must enter when
‘Iterative solution’ is chosen as calculation mode are described in
– Fully open: If this calculation mode is chosen the gate is fully open.
For an overflow gate this means that the gate level will equal the
Sill Level specified by the user. For underflow gates and radial gates if will correspond to the Max Level defined by the user. For a pump this corresponds to the maximum pump capacity specified as
Max Value.
– Close: If this calculation mode is chosen the gate is closed. For an overflow gate this means that the gate level will equal the Max
Level specified by the user. For underflow gates and radial gates if will correspond to the Sill Level defined by the user. For a pump this corresponds to a pump discharge equal to zero.
– Unchanged:If this calculation mode is chosen the gate level or the
pump discharge will remain unchanged.
MIKE 11
Tabular view: Structures
– Change with: If this calculation mode is chosen the gate level or the pumps discharge will change with the amount specified in the
Value column in the Control Definitions data section.
– Set equal to: If this calculation mode is chosen the gate level or the pumps discharge will equal the value specified in the Value column in the Control Definitions data section.
Control Type
Here the type of control point is chosen.
– h: Water level in a point.
– dh: Difference between water levels in two points.
– Q: Discharge in a point.
– dQ: Difference between discharges in two points.
– abs(Q): Absolute value of the discharge in a point.
– Q_Structure: The discharge through a structure.
– Sum_Q: The sum of flows in points and structures.
– V: Velocity in a point.
– Gate level: The level of a gate.
– Acc. Vol.: Accumulated volume running through a point.
– Time: The target point will be given as a time series.
– Min of hour: Integer expressing the minutes at the time of calculation.
– Hour of day: Integer expressing the hour at the time of calculation.
– Day of week: Integer expressing the day of the week at the time of calculation. Monday corresponds to one, tuesday to two and so on.
– Day of month: Integer expressing the day of the month at the time of calculation.
– Month of year: Integer expressing the month of the year. January corresponds to one, February to two and so on.
– Year: The year given as an integer value.
River Network Editor
97
98
River Network Editor
– Time after start: This control type is used in control strategies with a gate operation that can not be interrupted. An example could be a gate that closes from fully open to fully closed during half an hour when the water level downstream reaches a certain level. Because it is not known when the closing procedure is initiated it is not possible to describe it using a time series. Instead the gate level is described as a function of time measured relative to the time at which the procedure was initiated, i.e. the first value of the Control
Type ‘Time after start’ MUST always equal zero. If it is decided to operate a gate using this control type no other operating policies can be invoked before the actual gate operation has finished. In the example this means that no other operating policies can be used during the half hour it takes to close the gate.
– Concentration: A concentration of any compound.
– Hups: Water level just upstream of the structure.
– Hdws: Water level just downstream of the structure.
– Qups: Discharge just upstream of the structure.
– Qdws: Discharge just downstream of the structure.
– Vol: The volume of water in a point.
– Volups: The volume of water just upstream of the structure.
– Voldws: The volume of water just downstream of the structure.
– BranchVol: The volume of water in a certain part of a river branch
– Depth: The depth in a point.
– Area: The area in a point.
– DepthUps: The depth just upstream of the structure.
– DepthDws: The depth just downstream of the structure.
– AreaUps: The area just upstream of the structure.
– AreaDws: The area just downstream of the structure.
– ThisGate dh: The water level difference across the structure.
– ThisGate Q_Structure: The flow through the structure.
– ThisGate Gate Level: The gate level of the gate.
The use of references to the points up- and downstream of the structure and reference to the ThisGate enables a faster editing of the strategies because no location data must be entered.
MIKE 11
Tabular view: Structures
Target Type
Here the type of the target point is chosen.
– h: Water level in a point.
– dh: Difference between water levels in two points.
– Q: Discharge in a point.
– dQ: Difference between discharges in two points.
– abs(Q): Absolute value of the discharge in a point.
– Q_Structure: The discharge through a structure.
– Sum_Q: The sum of flows in points and structures.
– V: Velocity in a point.
– Gate level: The level of a gate.
– Concentration: A concentration of any compound. Note that concentration can not be used as target type if the calculation mode is chosen as ‘Iterative solution’.
– Hups: Water level just upstream of the structure.
– Hdws: Water level just downstream of the structure.
– Qups: Discharge just upstream of the structure.
– Qdws: Discharge just downstream of the structure.
– Vol: The volume of water in a point.
– Volups: The volume of water just upstream of the structure.
– Voldws: The volume of water just downstream of the structure.
– BranchVol: The volume of water in a certain part of a river branch
– Depth: The depth in a point.
– Area: The area in a point.
– DepthUps: The depth just upstream of the structure.
– DepthDws: The depth just downstream of the structure.
– AreaUps: The area just upstream of the structure.
– AreaDws: The area just downstream of the structure.
– ThisGate dh: The water level difference across the structure.
– ThisGate Q_Structure: The flow through the structure.
– ThisGate Gate Level: The gate level of the gate.
River Network Editor
99
River Network Editor
The use of references to the points up- and downstream of the structure and reference to the ThisGate enables a faster editing of the strategies because no location data must be entered.
Type of scaling:
– None: This is the default value. When this is chosen no scaling of the value of the target point will take place.
– Scaling with internal variable: When this is chosen the value of the target point will be scaled with the value of a specified internal
variable. See Control Strategy (p. 108) for a list of the internal vari-
ables that can be used as scaling factors.
– Scaling with time series. When this is chosen the value of the target point is scaled with a factor taken from a time series.
– Value: This column should be edited only if the calculation mode is chosen as either Change With or Set Equal to.
Details
When pressing the details button a new dialog pops up. This is used to enter the necessary details in defining the operating rules for control structures in Mike11. There are four property pages: ‘Logical Operands’, ‘Control- and Target point’, ‘Control Strategy’ and ‘Iteration/PID’.
Logical Operands
100
Figure 2.52
The Logical Operand property page.
As stated in Control Definitions (p. 94) it is possible to define a number of
conditions that all must be evaluated to TRUE if the whole ‘if’-statement
MIKE 11
Tabular view: Structures is to be evaluated as TRUE. These conditions are in Mike11 called ‘Logical Operands’.The logical operands are entered in the Logical Operand
property page, see Figure 2.52. Each row in this table corresponds to a
logical operand.
Note that it is not necessary to enter any logical operands for the ‘if’-state-
ment with the lowest priority. The control strategy belonging to this ‘if’statement is the default strategy and will always be executed when all other ‘if’-statements with higher priority are evaluated to FALSE. As an example think of a gate where the gate level is a known function of time.
In this case only one control strategy is needed. The control type will be
‘Time’ and the target type will be ‘Gate Level’. Calculation mode is chosen as ‘Direct Gate Operation’. It is not necessary to enter any logical operands because when only one control strategy is specified this strategy will have the lowest priority.
Operator. When set to “None” the value returned by the LO Type is the
value at the actual time step of the simulation. Choosing a different opera-
tor will allow for opening the Operator Selection dialog. See Figure 2.53.
This dialog come up when clicking the browse button in the column between the Operator column and the “Period” column.
River Network Editor
101
River Network Editor
102
Figure 2.53
Dialog for selection the operator
The choices available for operator are: z z z z z z
Maximum. This will return the maximum value since the start of the simulation.
Minimum. This will return the minimum value since the start of the simulation.
Average. This will return the average value since the start of the simulation.
Accumulated. This will return the accumulated value since the start of the simulation. This is only available for LO Types related to discharge.
Difference. This will return the difference over the time span defined by the period parameters.
Time derivative. This will return the derivative with respect to time over the time span defined by the period parameters.
MIKE 11
Tabular view: Structures z
Previous. This will return the value and the end of the previous time step.
The start and end time for the period which the operators should operate on is to specified. Both parameters are given as positive values being the number of hours back in time from actual time step. I.e. time=zero is the actual time step and time=24 is 24 hours earlier. Thus start time always has to be larger than end time.
The switch “Reset at each time step in time series” is valid for accumulated values only. The impact of selecting this is that the accumulation of values is reset to zero at each time there is a new time step available in the time series file which this logical operand is to be compared with.
LO Type: This field holds the type of Logical Operand.
– h: Water level in a point.
– dh: Difference between water levels in two points.
– Q: Discharge in a point.
– dQ: Difference between discharges in two points.
– abs(Q): Absolute value of the discharge in a point.
– Q_Structure: The discharge through a structure.
– Sum_Q: The sum of flows in points and structures. If this is chosen data must be entered in a special dialog. This dialog opens when pressing the ‘Sum of Q’-button to the right of the table. How to
enter data in this case is described in Sum of Discharges (p. 113).
– V: Velocity in a point.
– Gate level: The level of a gate.
– Acc. Vol.: Accumulated volume running through a point.
– Min of hour: Integer expressing the minutes at the time of calculation.
– Hour of day: Integer expressing the hour at the time of calculation.
– Day of week: Integer expressing the day of the week at the time of calculation. Monday corresponds to one, tuesday to two and so on.
– Day of month: Integer expressing the day of the month at the time of calculation.
River Network Editor
103
104
River Network Editor
– Month of year: Integer expressing the month of the year. January corresponds to one, February to two and so on.
– Year: The year given as an integer value.
– Concentration: A concentration of any compound.
– TS-Scalar: The logical operand is here a number given in a time series.
– Loop number: This is a special type. To illustrate the use, an example is appropriate: Imagine a situation where a certain water level downstream of the structure is required, but only under the condition that a minimum discharge through the gate is maintained. This requires two iteration loops. In the inner loop (the first one) an iteration will be performed in which the required water level downstream is achieved. In the outer loop (second loop) it is checked if the discharge is larger than or equal to the minimum discharge allowed. This check is performed AFTER the inner loop has converged. If the discharge is too low a new iteration takes place in which it is ensured that the discharge is not smaller than the minimum required. In order to be able to formulate such a problem in
Mike11 the Logical Operand type ‘Loop-Number’ has been implemented. The inner loop corresponds to ‘Loop Number’ equal to one, the next loop corresponds to ‘Loop Number’ equal to two and so on.
– TSLGLC: Making a simulation using a time step of five minutes will result in an update of the gate level for every five minutes.
Sometimes this gives too much information. Maybe the user is only interested in updating the gate level every hour. This can be achieved using this TSLGLC (Time Since Last Gate Level
Change) type of logical operand. This variable counts the time
since the gate level last changed and can thus be used to ensure that the gate level is not updated at every time step.
– TOF: Time Of Forecast. Used to decide if the simulation is in hindcast or forecast mode.
– Hups: Water level just upstream of the structure.
– Hdws: Water level just downstream of the structure.
– Qups: Discharge just upstream of the structure.
– Qdws: Discharge just downstream of the structure.
– Vol: The volume of water in a point.
– Volups: The volume of water just upstream of the structure.
– Voldws: The volume of water just downstream of the structure.
MIKE 11
Tabular view: Structures
– BranchVol: The volume of water in a certain part of a river branch
– Depth: The depth in a point.
– Area: The area in a point.
– DepthUps: The depth just upstream of the structure.
– DepthDws: The depth just downstream of the structure.
– AreaUps: The area just upstream of the structure.
– AreaDws: The area just downstream of the structure.
– ThisGate dh: The water level difference across the structure.
– ThisGate Q_Structure: The flow through the structure.
– ThisGate Gate Level: The gate level of the gate.
Branch Name LO1: This field contains the name of the branch with the
Logical Operand.
Chainage LO1: This field contains the chainage of the Logical Operand.
Name LO1: This field is used only when LO Type equals ‘Gate Level’,
‘Q_Structure’ or ‘TSLGLC’. Then this field holds the structure ID of the relevant structure.
Comp. No.: This field is used only when LO Type equals ‘Concentration’.
The field holds the number of the relevant component.
Branch Name LO2: This field is only used if the LO Type equals ‘dH’
(H
1
- H
2
) or ‘dQ’ (Q
1
which the H
2
or Q
2
- Q
2
). The field holds the name of the branch in
should be found.
Chainage LO2: This field is only used if the LO Type equals ‘dH’ (H
1
H
2
) or ‘dQ’ (Q or Q
2
point.
1
- Q
2
-
). The field holds the name of the chainage of the H
2
Sign: Here the operator used in the logical expression is used. The user
can choose between {<, <=, >, =>, =, <>}.
Use TS-value:
– No: If ‘No’ is selected the value of the Logical operand is compared to the value entered in the ‘Value’ field.
– Yes: If ‘Yes’ is selected the value of the Logical Operand is compared to the value found in the relevant time series.
River Network Editor
105
River Network Editor
Value: Here the value that must be compared with the logical operand is
entered.
Time Series File: This field holds information about the relevant time
series file in case that the Use TS-value is chosen as ‘Yes’ or in the situation where the LO Type is chosen to be ‘TS-Scalar’.
Time Series Item: This field holds the name of the item chosen from the
time series file that was selected in the Time Series File field.
Control and Target Point
106
Figure 2.54
The Control- and Target point property page.
Control Type: Here the type of Control Point is chosen. This field is
linked to the Control Type field described in Control Type (p. 97).
Branch, Control Point 1: This field contains the name of the branch with
the control point.
Chainage, Control Point 1: This field contains the chainage of the con-
trol point.
Name, Control Point 1: This field is used only when Control Type equals
‘Gate Level’ or ‘Q_Structure’. The field holds the structure ID of the relevant structure.
Comp. No., Control Point 1: This field is used only when Control Type
equals ‘Concentration’. The field holds the number of the relevant component.
MIKE 11
Tabular view: Structures
Branch, Control Point 2: This field is only used if the Control Type
equals ‘dH ‘(H
1
- H
2
) or ‘dQ’ (Q
1
branch in which the H
2
or Q
2
- Q
2
). The field holds the name of the
should be found.
Chainage, Control Point 2: This field is only used if the Control Type
equals ‘dH’ (H
1
- H
2
chainage of the H
2
) or ‘dQ’ (Q
1
or Q
2
point.
- Q
2
). The field holds the name of the
‘Sum of Q for Control Point’-button: This button is only activated if
Control Type is chosen as ‘Sum_Q’. How to enter the necessary data in
this case is described in Sum of Discharges (p. 113).
Target Point Type: Here the type of target point is chosen. This field is
linked to the Target Type field described in Target Type (p. 99).
Branch, Target Point 1: This field contains the name of the branch with
the Target point.
Chainage, Target Point 1: This field contains the chainage of the target
point.
Name, Target Point 1: This field is used only when Target Type equals
‘Gate Level’ or ‘Q_Structure’. Then this field holds the structure ID of the relevant structure.
Comp. No., Target Point 1: This field is used only when Target Type
equals ‘Concentration’. Then this field holds the number of the relevant component.
Branch, Target Point 2: This field is only used if the Target Type equals
‘dH’ (H
1
- H
2
) or ‘dQ’ (Q
1
branch in which the H
2
- Q
2
or Q
2
). Then this field holds the name of the
should be found.
Chainage, Target Point 2: This field is only used if the Target Type
equals ‘dH’ (H
1
- H
2
the chainage of the H
) or ‘dQ’ (Q
1
2
or Q
2
- Q
point.
2
). Then this field holds the name of
Operator. Similar to how logical operands can have an operator, this is
also possible with the value returned from a control point. Please refer to the descrition of operators for logical operands.
‘Sum of Q for Target Point’-button: This button is only activated if Tar-
get Type is chosen as ‘Sum_Q’. How to enter the necessary data in this
case is described in Sum of Discharges (p. 113).
River Network Editor
107
River Network Editor
Time Series File: This field holds information about the relevant time
series file in case that the Control Type is chosen as ‘Time’. If the button to the right of this field is pressed it is possible to browse for the file. At the same time the relevant item in the time series file can be selected.
Time Series Item: This fields hold the name of the item chosen in the
time series file that are selected in the Time Series File field.
Control Strategy
108
Figure 2.55
The Control Strategy property page.
Here the relationship between the value of the Control Point and the value of the Target Point are entered. This is done in the table on the left side of the property page.
Also the information about scaling of the target point are entered here. The
Type of Scaling field is linked to the Type of Scaling field described in
Target Type (p. 99). Below this field there are two sections: A ‘Scaling,
Internal Variables’ section and a ‘Scaling, Time series’ section. Both of these will be greyed out if ‘None’ is chosen as scaling type.
If Type of Scaling is chosen as ‘Scale with time series’ a dfs0 file containing the relevant time series can be allocated by pressing the button to the right of the ‘Time Series File’. At the same time the relevant item in the dfs0 file can be selected.
If Type of Scaling is chosen as ‘Scale with internal variable’ some of the following fields must be filled by the user:
MIKE 11
Tabular view: Structures
Variable Type: The type of internal variables that can be used are:
– h: Water level in a point.
– dh: Difference between water levels in two points.
– Q: Discharge in a point.
– dQ: Difference between discharges in two points.
– abs(Q): Absolute value of the discharge in a point.
– Q_Structure: The discharge through a structure.
– Sum_Q: The sum of flows in points and structures.
– V: Velocity in a point.
– Gate level: The level of a gate.
– Concentration: A concentration of any compound.
– Hups: Water level just upstream of the structure.
– Hdws: Water level just downstream of the structure.
– Qups: Discharge just upstream of the structure.
– Qdws: Discharge just downstream of the structure.
– Vol: The volume of water in a point.
– Volups: The volume of water just upstream of the structure.
– Voldws: The volume of water just downstream of the structure.
– BranchVol: The volume of water in a certain part of a river branch
– Depth: The depth in a point.
– Area: The area in a point.
– DepthUps: The depth just upstream of the structure.
– DepthDws: The depth just downstream of the structure.
– AreaUps: The area just upstream of the structure.
– AreaDws: The area just downstream of the structure.
– ThisGate dh: The water level difference across the structure.
– ThisGate Q_Structure: The flow through the structure.
– ThisGate Gate Level: The gate level of the gate.
The use of references to the points up- and downstream of the structure and reference to the ThisGate enables a faster editing of the strategies because no location data must be entered
River Network Editor
109
110
River Network Editor
Branch, Scale Point 1: This field contains the name of the branch with
the scaling point.
Chainage, Scale Point 1: This field contains the chainage of the scaling
point.
Name, Scale Point 1: This field is used only when Variable Type equals
Gate Level or Q_Structure. The field holds the structure ID of the relevant structure.
Comp No, Scale Point 1: This field is used only when Variable Type
equals Concentration. The field holds the number of the relevant component.
Branch, Scale Point 2: This field is only used if the Variable Type equals
dH (H
1
- H
2
which the H
) or dQ (Q
1
2
or Q
2
- Q
2
). The field holds the name of the branch in
should be found.
Chainage, Scale Point 2: This field is only used if the Variable Type
equals dH (H
1
- H
2
chainage of the H
2
) or dQ (Q
1
or Q
2
point.
- Q
2
). The field holds the name of the
‘Sum of Q for Scaling Point’-button: This button is only activated if
Variable Type is chosen as Sum_Q. How to enter the necessary data in this
case is described in Sum of Discharges (p. 113).
Iteration / PID
PID-Section: Here the necessary data is entered if the calculation mode is
chosen as PID-operation.
MIKE 11
Tabular view: Structures
River Network Editor
Figure 2.56
The Iteration / PID property page when calculation mode is chosen as PID-Operation.
Integration Time, Ti: Corresponds to T
i
Derivation Time, Td: Corresponds to T
d
Proportionality Factor, K: Corresponds to K in eqn. (2.1).
Weighting factor for time step 1, a1: Corresponds to
α
1
in
Weighting factor for time step 2, a2: Corresponds to
α
2
in eqn.
Weighting factor for time step 3, a3: Corresponds to
α
3
in eqn.
Iteration-Section: Here the necessary data is entered if calculation mode
is chosen as Iterative solution. When making an iterative solution it is necessary to define some criteria for when the solution is acceptable. Mike11 use a criteria that can be expressed like:
TP
Required
–
Limit
Low
≤
TP
Act
≤
TP
Required
+
Limit
High
(2.2) where TP
Required
is the required value of the target point, TP
Act
value of the target point, Limit
Low
is the actual
is the amount that the actual value of the target point can be smaller than the required target point and Limit
High
is the amount that the actual value of the target point can be larger that the required value of the target point.
111
River Network Editor
112
Figure 2.57
The Iteration / PID property page when calculation mode is chosen as Iterative Solution.
Value -: This field corresponds to Limit
Low
Value +: This field corresponds to Limit
High
Use absolute or relative value: Two options exist: ‘Absolute’ and
‘Relative. When choosing ‘Absolute’ the limits in the convergence interval given in the ‘Value -’ and the ‘Value +’ fields are interpreted as absolute values. If ‘Relative’ is chosen the values are interpreted as fractions of the requested value of the target point.
Example: Suppose that the Target Point is the water level downstream of the gate and the requested value of the Target Point is 20.
Limit
Low
and Limit
Low
are both equal to 0.2. If ‘Absolute’ is chosen the iteration stops when the actual water level is between 19.8 and
20.2. If ‘Relative’ is chosen the iteration stops when the actual value is between 16 and 24
Max. Change of Gate Level: This field holds the maximum
change of the gate level (or discharge in case of a discharge gate) that can take place during one iteration and will be used as the first guess at the change in gate level. Both positive and negative values can be entered. In this way the user can make sure that the first guess at a new level makes the iteration go in the right direction.
MIKE 11
Tabular view: Structures
Sum of Discharges
River Network Editor
Figure 2.58
Input page to Sum of Discharges.
It is possible to add any number of discharges and use this as a Control
Type, Target Type, Scaling Type or a Logical Operand. The discharges can be taken from any grid point and any structure in the setup. Further each discharge can be multiplied with a user defined factor. This factor can be both positive and negative. The sum of Q can be expressed as: sum of Q =
i
=
n
∑
i
= 1
fac i
Q i
(2.3)
n is the number of discharges to sum, fac
i
the ith discharge, Q
i
.
the factor to be multiplied with
Factor: This corresponds to fac
i
Type: This holds the type of discharge to add.
– Discharge in grid point: A discharge in a grid point is selected.
– Structure discharge: The discharge in a structure is selected. Note that this is not the same since you can have several structures in the same grid point.
– Qups: Discharge just upstream of the structure.
– Qdws: Discharge just downstream of the structure.
– ThisGate Q_Structure: The flow through the structure.
113
River Network Editor
The use of references to the points up- and downstream of the structure and reference to the ThisGate enables a faster editing of the strategies because no location data must be entered.
Branch: The name of the branch with the grid point / structure from
which the discharge should be taken.
Chainage: The chainage of the grid point / structure.
Struc. Name: In case Structure Discharge has been chosen as the type the
structure ID must be given here.
2.3.9
Dambreak Str.
General
Most dambreak setups consist of a single or several channels, a reservoir, the dam structure and perhaps auxiliary dam structures such as spillways, bottom outlets etc. Further downstream the river may be crossed by bridges, culverts etc. It is important to describe the river setup accurately in order to obtain reasonable results. There is no limit to the number of dam structures in a MIKE 11 model.
River channel setup
Setting up the river channel description in the cross-section data base is the same for dambreak models as it is for other types of models. However, due to the highly unsteady nature of dambreak flood propagation, it is advisable that the river topography be described as accurately as possible through the use of as many cross-sections as necessary, particularly where the cross-sections are changing rapidly.
Another consideration is that the cross-sections themselves should extend as far as the highest modelled water level, which will normally be in excess of the highest recorded flood level. If the modelled water level exceeds the highest level in the cross-section data base for a particular location, MIKE 11 will extrapolate the PROCESSED data.
Reservoir description and appurtenant structures
In order to obtain an accurate description of the reservoir storage characteristics, the reservoir can be modelled as a single h-point in the model.
This point also corresponds to the upstream boundary of the model where inflow hydrographs are specified.
The description of the reservoir storage is carried out directly in the processed data. The only columns which contain 'real' data are those containing the water level and the additional flooded area.
114 MIKE 11
Tabular view: Structures
In this way the surface storage area of the dam is described as a function of the water level. The lowest water level should be somewhere below the final breach elevation of the dam, and should be associated with some finite flooded area. (This first value, hence, describes a type of 'slot' in the reservoir).
The cross-sectional area is set to a large finite value. It is only used when calculating the inflow headloss into the breach.
It may be practical to locate the dambreak structure on a separate branch
containing only three calculation points, as shown in Figure 2.59.
River Network Editor
Figure 2.59
Typical setup for dambreak simulation
The dam
At the Q-point where the dambreak structure is located, the momentum equation is replaced by an equation which describes the flow through the structure. This may be either critical or sub-critical. A check on the energy levels at the structure and at the next downstream h-point is first carried out to determine which description is applicable. Refer to the MIKE 11
HD Reference Manual, Dambreak Section.
As the momentum equation is not used at the Q-point, the
∆X step used between the adjoining h-points is of no consequence. The maximum
∆X step should, however, be greater than the difference between given chainages to prevent the insertion of interpolated cross- sections.
Spillways and other structures
If a spillway is added to the dam itself, it could be described as a separate
115
River Network Editor
At the node where the two branches meet, the surface flooded area is taken as the sum of the individual flooded areas specified at each h-point.
Hence, if the reservoir storage has already been described in the reservoir h-point, the spillway h-point should contain no additional surface areas. In this case both the width and the additional flooded areas should be set to zero. The cross-sectional area, hydraulic radii, etc. can be given as for the reservoir branch.
It is not a requirement that a separate branch for the spillway structure is defined. The dambreak and the spill way structure can be located in the same grid point, i.e. as a composite structure. The advantage of having two separate branches is that the discharge through the spillway and the dambreak structure is given as two separate time series in the result file.
Specifying the Dambreak
116
Figure 2.60
The Dambreak structure property page.
MIKE 11
Tabular view: Structures
This Dambreak structure property page is used for inserting dambreak
structures in a given network. The property page (see Figure 2.60) consists
of a number of dialog boxes whose functionality is described below.
Location
– River Name: Name of the river branch in which the dambreak is located.
– Chainage: Chainage at which the dambreak is located.
– ID: String identification of the structure. It is used to identify the structure if there are multiple structures at the same location. It is recommended always to give the structure an ID.
– Type: The lcation type may be Regular, Side Structure or Side
Structure + Reservoir. See section 2.3 Tabular view: Structures for details
Breach Calc. method
The calculation of the dam break may be carried out using either the energy equation or alternatively the National Weather Service (NWS) dambreak equations. Only the former allows the breach to be erosion based. If the latter is chosen the type of the initial breach must also be selected. The choices are
– Breach failure: The dam break initiates as a breach of the crest.
– Piping failure: The dam break initiates as a piping failure. The shape of the pipe being trapezoidal.
Dam Geometry
– Crest Level: The crest level of the dam before failure.
– Crest Length: The crest length (perpendicular to the flow) of the before failure.
Limit for Breach Development
Not applicable to the NWS calculation routines.
– Apply limiting cross section:
No: The development of the breach will be unlimited.
Yes: The development of the breach is limited (e.g. solid rock below
the dam). The shape of the limitation should be specified in the
Cross Section Editor (p. 153).
River Network Editor
117
118
River Network Editor
– Topo ID: Topo ID applied when using a limiting section in the cross section file
– River Name: River Name applied when using a limiting section in the cross section file
– Chainage: Chainage applied when using a limiting section in the cross section file
– X-coor at centre breach: The x-coordinate of the breach centerline specified in the coordinate system applied for the raw data of the limiting section.
Head Loss Factors
The factors determining the energy loss occurring for flow over/through the hydraulic structure. Only required for the energy loss method.
Failure Moment and Mode
The moment at which the dam failure commences can be defined in three ways:
1 Hours after Start: The failure is specified to take place a specified number of hours after the start of the simulation.
2 Date and Time: The failure time is specified as a date and time.
3 Reservoir water level: The failure is specified to take place when the water level in the reservoir (assumed to be the grid point immediately upstream of the dam) exceeds a certain level.
The development of the breach can take place in two different ways:
1 Time Dependent: The development of the dam breach is specified by the user in terms of breach level, width and slope as functions of time.
Additionally if a NWS piping failure is selected the top level of the pipe must also be specified. This specification takes place through the
2 Erosion Based: MIKE 11 calculates the breach development by use of a sediment transport formula for which the parameters are specified in
Note: That the erosion based method is only available when selecting the
energy equation based calculation mode.
Time Step Control
This feature is only applicable when using a fixed time step. At the specified time after failure the time step is multiplied with the given factor and
MIKE 11
Tabular view: Structures the remainder of the simulation is carried out with the new increased time step.
– Time after failure when changing the time step: Time for the increase of time step relative to the failure time and specified in hours.
– Factor by which the time step is multiplied: Time step amplification factor. The factor must be larger than one corresponding to an increase in the time step.
It is recommended to use an adaptive time step as an alternative to this feature.
Making dambreak simulations
Initial Conditions
In many cases dam failures occur on a dry river bed downstream. However, such initial conditions should be treated with caution in MIKE 11.
Hence, before a dambreak is actually simulated, it is expedient to create a steady-state 'hot start' file which can be used for all subsequent dambreak simulations.
The easiest method of creating such a file is to make a setup identical to that used for the dambreak, with the following exceptions:
1 A small lateral inflow is added at the first h-point in the river downstream of the dam. This will ensure some depth of water in the river from which a steady-state can be reached
2 The inflow into the reservoir can be non-zero, if desired.
3 The dambreak structure should be specified not to fail, i.e. to ensure that the maximum calculated reservoir level is greater than the specified failure reservoir level (i.e. failure will not occur during the generation of the steady- state hot start file).
Initial conditions (h and Q) for this 'hot start' simulation must be specified in the supplementary data, including the reservoir level.
This setup should be run until a steady-state condition is reached (Q = constant = lateral inflow at the downstream boundary). If this file (.res11) is very large, a further simulation can be carried out by using this as a hot start and run it for a few time steps, using the same boundary conditions as previously. This smaller file can then be used for all future hot starts and the larger file can be discarded.
River Network Editor
119
River Network Editor
With the hot start file ready, the dambreak simulation can now be carried out. It is suggested that a DELTA value of slightly more than the default of
0.5 be used to damp out short waves which may lead to numerical instabilities. A time step of the order 1-10 minutes is suggested.
2.3.10 Dambreak Erosion
120
Figure 2.61
The Erosion property dialog.
This dialog (Figure 2.61) is accessed from the Dambreak Str. (p. 114)
property page in the Tabular view: Structures (p. 51) by pressing the
. button (can only be accessed if the Failure Mode is set to Erosion Based). The dialog can only be used to specify erosion based failure modes.
Purpose
The breach depth relationship is calculated using the Engelund-Hansen sediment transport formula. Breach width is determined from the product of breach depth and the side erosion index specified by user.
Dambreak Geometry
z
Upstream slope: Slope (horizontal: vertical) of the upstream face of the dam structure. z
Downstream slope: Slope (horizontal: vertical) of the downstream face of the of the dam structure.
MIKE 11
Tabular view: Structures z
Top Width: The top width of the dam crest.
Material Properties
z
Grain Diameter: Representative grain diameter of the dam core material. z
Specific Gravity 2.5 - 2.7: Relative density of the dam core material. z z z
Porosity 0.3 - 0.5: Porosity of the dam core material.
Crit. Shear Stress 0.03 - 0.06: Critical shear stress of dam core material used for sediment transport estimation (Shields criteria).
Side Erosion Index: Multiplication factor used to calculate breach width erosion rates from breach depth predictions.
Limit of Breach Geometry
The breach will continue developing until it has reached the breach geometry limit, which is defined by z z z
Final bottom level: The minimum level to which the breach is allowed to develop.
Final bottom width: The maximum width to which the breach is allowed to develop.
Breach slope: Slope (horizontal: vertical) on either side of the breach.
Initial Failure
The failure of the dam can initially take place in two ways: or
– as a breach starting at the top of the dam
– as a piping failure through the dam.
Breach Failure
z
Initial Level: The level of the breach develops in one time step as an initial breach shape. z
Initial Width: The width of the breach develops in one time step as an initial breach shape.
Piping Failure
z
Starting Level: The level at which piping failure begins to occur. z
Initial Diameter: The diameter of the piping breach which develops in one time step as an initial breach shape.
River Network Editor
121
River Network Editor z z z z
Roughness: Pipe roughness used to calculate the Darcy friction factor.
Collapse Ratio (D/y) > 0: When the ratio between the diameter of the pipe (D) and the distance from the top of the dam to the top of the pipe is larger than the collapse ratio the pipe collapses.
Volume Loss Ratio 0 - 1: When the dam collapses some of the material may be carried out without depositing on the bed of the breach. The volume loss ratio is the fraction of the material to be washed out immediately after collapse.
Calibration Coef. > 0: Calibration multiplication factor used to adjust the calculated change in pipe radius.
2.3.11
User Defined Structure
122
Figure 2.62
The User Defined Structure property dialog.
The user defined structure is available to create customised structures in
MIKE11. However, the potential application goes beyond this, allowing for the customisation of almost any specialist application or modification to MIKE11.
MIKE 11
Tabular view: Structures
When activated, the user defined structure will access a DLL (Dynamic
Link Library) written by the user. The Network Editor interface contains a number of variables that can be used in the DLL. In addition, the DLL can access any variable in MIKE11 through several records.
MIKE11 is written in PASCAL using Borland DELPHI. Any code written must be compatible with the compiled unit files (DCU) provided. The easiest way to ensure this is to have Delphi and write your programs in PAS-
CAL.
For more information, see the Reference Manual.
2.3.12 Tabulated Structure
River Network Editor
Figure 2.63
The Tabulated Structure property dialog.
The Tabulated Structure property page is used for defining a structure regulated by a user defined relation between the discharge through the structure and the up- and downstream water level. The relation is defined in a table. The property page consists of a number of dialog boxes (see
Figure 2.63) whose functionality is described below:
123
124
River Network Editor
Details
River Name: Name of the river branch in which the structure is
located.
Chainage: Chainage at which the structure is located.
Structure ID: String identification of the structure. This has no influ-
ence on the simulation. It is only used to identify multiple structures at a single location within a result file.
Type: The lcation type may be Regular, Side Structure or Side Struc-
ture + Reservoir. See section 2.3 Tabular view: Structures for details
Calculation Mode:
Q = f(h U/S, h D/S): The discharge is given as a function of the up-
and downstream water level. The upstream water level (h U/S) must be tabulated in the first column and the downstream water level (h
D/S) must be tabulated in the first row in the table. Then the corresponding discharges must be tabulated.
The upstream water level must increase in the right direction and the downstream water level must increase in the downward direction. The discharge can not increase in the right direction and it can not decrease in the downward direction.
H U/S= f(h D/S, Q): The upstream water level is given as a func-
tion of the discharge and downstream water level. The downstream water level (h D/S) must be tabulated in first column and the discharge must be tabulated in the first row in the table. Then the corresponding upstream water levels must be tabulated.
The discharge must increase in the right direction and the downstream water level must increase in the downward direction. The upstream water level must increase in the right and the downward direction.
H D/S= f(h U/S, Q): The downstream water level is given as a
function of the discharge and upstream water level. The upstream water level (h U/S) must be tabulated in the first column and the discharge must be tabulated in the first row in the table. Then the corresponding downstream water levels must be tabulated.
The discharge must increase in right direction and the upstream water level must increase in the downward direction. The down-
MIKE 11
Tabular view: Structures
2.3.13 Energy Loss
stream water level must decrease in the right direction and increase in the downward direction.
Number of Columns: Set number of columns in the table. The
number of columns must be 4 or higher. A large number of columns will increase the accuracy and the stability of the results.
Number of Rows: Set number of rows in the table. The number of
rows must be 4 or higher. A large number of rows will increase the accuracy and the stability of the results.
Water level datum: The water level datum is added to the up- and
downstream water level in the table.
Discharge factor: The discharge factor is multiplied to the discharge
in the table.
River Network Editor
Figure 2.64
Energy Loss property page dialog.
The Energy Loss property page is used to define energy losses associated with local flow obstructions such as sudden flow contractions or expan-
125
126
River Network Editor sions and gradual or abrupt changes in the river alignment. Moreover, a user defined energy loss coefficient can be defined.
At each specified Energy Loss point a discharge grid point is inserted at run-time. At each time level of the computation the discharge at Energy
Loss points is computed by use of the energy equation:
∆H
=
------------
2gA
2
(2.4) in which
∆H is the energy loss, g is the acceleration of gravity, Q is the discharge and A is the cross-sectional wetted area. The quantity,
ζ, denotes the energy loss coefficient as specified in the Energy Loss property page dialog.
Details:
River name: Name of the river in which the Energy Loss point is
located.
Chainage: Chainage at which the Energy Loss point is located.
ID: String identification of the Energy Loss point. The specified ID has
no influence on the simulation.
Apply energy loss: Determines whether, or not, the associated energy
loss type is applied in the simulation.
Alignment change: Denotes the angular change in river alignment at
the Energy Loss point in question.
Roughness coefficient: The roughness coefficient is of the order of 0.2
for rough pipes and of the order of 0.1 for smooth pipes.
Positive flow: Denotes the energy loss coefficient in the case of posi-
tive flow across the Energy Loss point in question. Applies to user defined loss, contraction loss and expansion loss.
Negative flow: Denotes the energy loss coefficient in the case of nega-
tive flow across the Energy Loss point in question. Applies to user defined loss, contraction loss and expansion loss.
Overview table: Contains information on all kinds of energy losses
applied at each Energy Loss point within the river network.
MIKE 11
Tabular view: Routing
2.4
Tabular view: Routing
Routing is a simplified hydraulic calculation. Normally, simulation of how a flood wave or a hydrograph propagates along a branch is based on solving the St. Venant equations. This requires cross section information, however, if such is not available routing may be an alternative. There are no water levels calculated in routing branches, and what routing does is transforming a hydrograph, i.e. Using the inflow hydrograph at the upstream end of a branch (provided either as a boundary condition or coming from the upstream node of the branch) as input routing calculates the outflow hydrograph. Typically a routing element represents a reach of a river or a flood control device such as a reservoir or a hydraulic control structure.
To allow for the insertion of routing components into a branch the branch
type must be set to “Routing”. See section 2.2.2 Branches (p. 43).
Any number and combination of routing components are allowed. If no routing components are inserted in a routing branch, the outflow will equal the inflow. The order of the routing components are determined by the chainage of the components. However, additional inflow can also be added as the runoff from a catchment.
A routing component is any of the data types described in the following sections.The order of the routing components are determined by the chainage of the components.
Routing can be combined with normal hydrodynamic simulation such that in some branches routing is applied while in others hydrodynamic simulation is done. The only requirement is that at the upstream end of a routing branch there should either be no other branch connected, or only branches which are routing branches as well.
A hydraulic simulation always requires for instance a cross section and a
HD parameter file. I.e. if routing is applied in all branches empty cross section (.xns11) and HD parameter file (.HD11) data files should created, and reference made to these in the simulation editor.
If the upstream end of a routing branch has no connection to other branches a discharge boundary condition is required at this location. This also applies if inflow is only to be supplied as catchment runoff. In such case a dummy discharge boundary condition with Q=0 must be specified.
2.4.1
Channel routing
The dialog for specifying the parameters for channel routing is shown in
River Network Editor
127
River Network Editor
128
Figure 2.65
Dialog for channel routing.
In the dialog the user should specify the following parameters:
Name: Name of the branch where the routing component is located.
Chainage: Chainage at which the routing component is located.
ID: Name of the routing component. Does not influence the simulation.
Type: Currently only non-linear storage is implemented.
K1, P1, Q1, K2, P2, Tl, Tlz: Parameters for the calculation. See technical
reference for more details.
Alpha, P, ALR, SR and ANR: Parameters for kinematic wave. See tech-
nical reference for more details.
NOTE! The Non-Linear Storage Function method includes a number of
default ’Advanced’ variables which are editable for the user through the
MIKE11.Ini file. These variables comprise; ’Error1’, ’Error2’, ’IR1’ and
’IR2’.
MIKE 11
Tabular view: Routing
2.4.2
Flood control Q and Q-rate
The dialog for specifying the parameters for “Flood control Q and Q-rate”
Figure 2.66
Dialog for flood control Q and Q-rate.
In the dialog the user should specify the following parameters:
Name: Name of the branch where the routing component is located.
Chainage: Chainage at which the routing component is located.
ID: Name of the routing component. Does not influence the simulation.
Type: The user should select the actual type of flood control.
Q, Q2, Q3, FACA, FACB, VMAX: Parameters for the calculation.
Depending on the selected type of flood control fewer or more or the parameters are required. See technical reference for more details.
2.4.3
Flood control H-Q / H-V curve
The dialog for specifying the parameters for “Flood control H-Q/H-V
curve” is shown in Figure 2.67.
River Network Editor
129
River Network Editor
130
Figure 2.67
Dialog for flood control H-Q / H-V curve.
In the dialog the user should specify the following parameters:
Name: Name of the branch where the routing component is located.
Chainage: Chainage at which the routing component is located.
ID: Name of the routing component. Does not influence the simulation.
Type: The user should select the actual type of flood control.
Initial water level: If checked the water level specified will be applied,
otherwise the initial water level will be equal to the water level giving an outflow equal to the initial inflow.
Water level / Storage volume: A table of water levels and corresponding
storage volumes.
Water level / Outflow: A table of water levels and corresponding out-
flow.
NOTE! The Flood Control H-q / H-V method includes a number of
default ’Advanced’ variables which are editable for the user through the
MIKE11.Ini file. These variables comprise; ’Error’, and ’IBUN’.
MIKE 11
Tabular view: Routing
2.4.4
Flood control by orifice
The dialog for specifying the parameters for “Flood control by orifice” is
Figure 2.68
Dialog for flood control by orifice.
In the dialog the user should specify the following parameters:
Name: Name of the branch where the routing component is located.
Chainage: Chainage at which the routing component is located.
ID: Name of the routing component. Does not influence the simulation.
Additionally a range of parameters should be specified. See the reference manual for more details.
2.4.5
Diversions
The dialog for specifying the parameters for a diversion is shown in
River Network Editor
131
River Network Editor
132
Figure 2.69
Dialog for diversion of flow.
Normally when applying the routing facilities the network does not split the flow as a proper calculation of the split requires a water level to be calculated. However, using the diversion facility the user is allowed to specify how a branch splits into two branches. This is done by pre-defining the split of flow, i.e. for a range of inflow discharges the amount continuing along the main branch and along the tributary branch should be specified.
In the dialog the user should specify the following parameters:
River U/S: Name of the branch coming from upstream.
ID: Name of the routing component. Does not influence the simulation.
Main River D/S: Name of the first downstream branch.
Tributary D/S: Name of the second downstream branch.
Inflow, Main channel Q, Tributary Q: For a range of inflow discharges
the amount continuing along the main branch and along the tributary branch should be specified.
Whether the main river downstream carries the majority of the flow does not matter.
MIKE 11
Tabular view: Routing
This facility does not allow a routing branch to split be into more than two branches. If this is required an artificial routing branch with no routing
elements has to be applied. Figure 2.70 shows how this is done when a
branch splits into three branches.
Artificial branch
Splitting into three branches is not allowed for routing branches.
Adding an artificial branch allows for splitting into three branches
Figure 2.70
Splitting routing branch into three branches.
2.4.6
Kinematic Routing Method
Kinematic Routing can be used to model the hydraulics of upstream tributaries and secondary river branches, where the main concern is to route water to the main river system. The Kinematic Routing method does not facilitate the use of structures at Kinematic Routing branches. Moreover, the method does not account for backwater effects.
Since the Kinematic Routing method is unconditionally stable, it facilitates the use of large time steps, which is important when running the model in parallel with the hydrological model, MIKE SHE.
At Kinematic Routing branches, it is possible to run the model without information on cross-sections. In turn, this indicates that Kinematic Routing branches can not be used to model a looped part of a river network.
Employment of Kinematic Routing branches requires that all branches located upstream of a Kinematic Routing branch are defined in the same way.
River Network Editor
Figure 2.71
Definition of Kinematic Routing branches.
133
River Network Editor
134
Figure 2.72
Definition of Kinematic Routing elements.
The dialog used to define a Kinematic Routing branch is shown in
Figure 2.71, while the dialog used to define Kinematic Routing elements
Details
Location
River name: Name of the river in which the Kinematic Routing point
is located.
Chainage: Chainage at which the Kinematic Routing point is located.
ID: String identification of the Kinematic Routing point. The specified
ID has no influence on the simulation.
Discharge Computation
Muskingum method: A routing method that requires the following
input parameters:
– K: Time scale describing the travel time of the water through the
Kinematic Routing element in question.
– x: A weighting factor greater than zero and smaller than 0.5.
Muskingum-Cunge method: A routing method that does not require
any input parameters. At each time level of the computation, the method computes the spatial variation of K and x, cf. above, the intention being to approximate the diffusion of a natural flood wave.
MIKE 11
Tabular view: Runoff / Groundwater Links
No transformation: Employment of this option indicates that the
flood wave is not transformed in passing the Kinematic Routing element in question.
Water Level Computation
User-defined discharge-elevation method: Employment of a dis-
charge-elevation relation indicates that the water level is looked up in the specified table using as input to the interpolation scheme the computed discharge. If this method is adopted, cross-sections need not be specified in the cross-section editor.
Resistance method: Employment of his option indicates that the Man-
ning resistance method is used to compute the water level. This method requires as input cross-section information, the computed discharge and a bed resistance value.
2.5
Tabular view: Runoff / Groundwater Links
This section gives details of how to implement possible links to a rainfall runoff model or linkage to DHI’s groundwater model MIKE SHE.
River Network Editor
135
2.5.1
MIKE SHE Links
River Network Editor
136
Figure 2.73
MIKE SHE links dialog.
Include all branches
If this button is pressed all branches included in the MIKE 11 set-up are copied to the MIKE SHE coupling page. Branches that should not be in the coupling can subsequently be deleted manually and remaining specifications completed. Thus you may have a large and complex hydraulic model, but only couple (certain reaches of) the main branches to MIKE
SHE. All branches will still be in the hydraulic MIKE 11 model but MIKE
SHE will only exchange water with branch reaches that are listed in the
MIKE SHE coupling definition page.
Observe that the Include all branches feature will overwrite existing specifications.
Location
Branch name, US and DS Chainage
The name of the branch and the upstream and downstream chainage for the river reach where the MIKE SHE coupling should be used. One branch
MIKE 11
Tabular view: Runoff / Groundwater Links can be sub-divided into several reaches. A reason for doing so could be to allow different riverbed leakage coefficients for different reaches of the river.
Leakage
Exchange Type
a, b or c should be chosen and refer to the 3 different river aquifer exchange types (described in the technical documentation of the MIKE
SHE User Manual) of exchange between surface water and aquifer. When the MIKE 11 coupling is used the exchange type specification in MIKE
SHE is ignored.
Leakage Coefficient (1/s)
Leakage coefficient for the riverbed lining (see exchange documentation).
The leakage coefficient is relevant only if the exchange type is either b or c.
Inundation
Flood Area Option
The Flood Area or Inundation Area option is one of the new facilities in
MIKE SHE and allows that a number of model grids are flooded (being part of a river, lake, reservoir etc.). The flood area may be defined as no flooding, auto(matic) or manual. These three may also be used in parallel for different branches or even for specific coupling reaches within the same branch
If the no flooding option is adopted rivers are considered lines located between adjacent model grids. No flooding can occur and over-bank spilling is not possible.
If the auto(matic) or manual option is used a river or a lake (with wide cross-sections) may cause flooding of a number of grids in MIKE SHE. A reference system is established between MIKE 11 h-points and individual model grids in MIKE SHE. Subsequently a simple flood-mapping procedure is adopted to calculate water stage on the ground surface (in MIKE
SHE). The flood mapping procedure simply compares simulated water levels (in an h-point) with the ground surface elevation in reference grids.
If the water level is higher than the ground surface elevation, flooding occurs. The reference system between h-points and model grids may be established automatically by MIKE SHE or it may be established (partly) manually (see below). Each (potentially flooded) MIKE SHE grid point is
River Network Editor
137
138
River Network Editor referenced to the nearest MIKE 11 h-point on a coupling reach with the same floodcode value. z
No Flooding
The no flooding option is equivalent to the old formulation in MIKE
SHE where rivers are considered a line between two adjacent model grids. If this option is used one of the three river-aquifer exchange formulations will be adopted. River-Overland exchange is always oneway, namely overland to river. Over-bank spilling is not possible when the No flooding formulation is adopted. The river water level may rise above the topographic elevation of the adjacent grids without flooding the grids.
If the no flooding option is applied the floodcode is not used.
z
Automatic Flood Area Option
The automatic flood-area option is often useful if the geometry of rivers, lakes etc. is not too complex. Thus, for instance, if a large wide river without too much meandering is considered, the automatic flood area option will typically be feasible.
When the automatic option is chosen, MIKE SHE's set-up program will automatically generate the potentially flooded areas (flood grid code map) depending on the location of the individual rivers and on the width and location of the river cross-sections. The specified coupling reach floodcode is used as grid code, and the flood-mapping procedure described above is applied. Thus it is important to use unique coupling reach floodcode values to ensure correct mapping to the corresponding grid points.
z
Manual Flood Area Option
The manual option allows the user to delineate the potentially flooded areas, using a T2 grid code file - the floodcode file specified in MIKE
SHE's user interface. If the river system considered is a very complex system with looped networks, meandering generating a complicated geometry, it will typically give the best result to create a floodcode file manually by digitising the floodplain / lake delineation and use this option.
The flood-mapping procedure above is applied. The potentially flooded area of each coupling reach must be defined with a unique integer grid code value in the floodcode file, and the same integer value specified as coupling reach floodcode.
MIKE 11
Tabular view: Runoff / Groundwater Links
Flood Code
Specification needed when the automatic or manual flood area option is chosen.
As described above the coupling reach floodcode is used for mapping
MIKE SHE grids to MIKE 11 h-points, and for the automatic option also for generating the flood grid codes of the actual coupling reach. It is important to use unique floodcodes to ensure correct flood-mapping.
Bed Topography
Specification needed when the automatic or manual flood area option is chosen.
The MIKE SHE ground surface elevation can be re-defined in flood area grid points, depending on the bed topography option. It should be emphasised that the flood mapping and dynamic flooding during the simulation requires a good consistency between the MIKE 11 cross-sections and the ground surface elevations of the corresponding MIKE SHE flood grid points.
z
Use Cross-section
When this option is specified the ground surface elevations of the actual flood grid points are substituted with values directly interpolated from the MIKE 11 cross-sections of the actual coupling reach. The setup program performs an inverse-distance-weighted interpolation, using points (elevations) on the MIKE 11 cross-sections as discrete input points. When the distance between individual MIKE 11 cross-sections is higher than ½ Dx (grid size) extra discrete points are generated by linear interpolation between the MIKE 11 cross-sections before the grid interpolation is made. This is done to ensure that an approximate river cross-sectional topography is incorporated in all MIKE SHE grids along the river and not only where a MIKE 11 cross-section is located.
Please note that the interpolated grid values are only used inside the area delineated by the MIKE 11 cross-sections used for interpolation.
When the manual flood area option is used, the user defined flood area is not necessarily identical with the flood area covered by the MIKE 11 cross-sections. If the automatic flood area option is used the area covered by the MIKE 11 cross-sections and the flood area will always be consistent, as the flood-area is generated (automatically) based on the
MIKE 11 cross-sections.
In principle the use cross-section option ensures a good consistency between MIKE SHE grid elevations and MIKE 11 cross-sections.
River Network Editor
139
140
River Network Editor
There will, however, often be interpolation problems related to river meandering, tributary connections, etc. where wide cross-sections of separate coupling reaches overlap. Thus it is recommended to make the initial MIKE SHE set-up using the Use Cross-section option and then subsequently retrieve and check the resulting ground surface topography (using the MIKE SHE Input Retrieval tool). If needed the retrieved ground surface topography (T2 file) can be modified (MIKE SHE
Graphical Editor) and then used as input for a new set-up, now using the use grid data option described below.
z
Use Grid Data
MIKE SHE grid data is used instead of MIKE 11 cross-sections. It is checked whether the optional bed elevation file has been specified in
MIKE SHE's user interface:
– Bed Elevation File specified
When the bed elevation file has been specified the ground surface elevations of the actual flood grid points are substituted with values from the specified T2 file. The option is useful when the surface elevation data of the flood areas is more detailed than the regional terrain model.
– Bed Elevation File not specified
The regional MIKE SHE surface topography is also used in flood areas.
As described above the specified T2 file will often be a retrieved and modified surface topography from a previous set-up with use cross-section option.
Bed Leakage
Specification needed when the automatic or manual flood area option is chosen.
As described in the technical documentation the infiltration/seepage of
MIKE SHE flood grids is calculated as ordinary overland exchange with the saturated or unsaturated zone, either using full contact or reduced contact with a specified leakage coefficient.
The bed leakage option tells whether the overland-groundwater exchange option and leakage coefficient specified in MIKE SHE's user interface should also be used in the actual flood area, or substituted by the corresponding river-aquifer Exchange Type and Leakage Coefficient specified for the actual coupling reach.
MIKE 11
Tabular view: Runoff / Groundwater Links z
Use grid data
The overland-groundwater exchange option and leakage coefficient specified in MIKE SHE's user interface is used. Both can be single value or distributed (T2 file).
z
Use river data
The MIKE SHE overland-groundwater exchange option and leakage coefficient in flood grid points are substituted with the corresponding river-aquifer Exchange Type and Leakage Coefficient specified for the actual coupling reach. Please note that the two reduced contact options
(exchange types B and C) result in the same overland-groundwater exchange option.
The substitution is made in all flood grid points of the actual coupling reach.
Overview of MIKE SHE coupling reaches
This box presents an overview of the link with MIKE SHE.
2.5.2
Rainfall-runoff links
River Network Editor
Figure 2.74
Rainfall-runoff links dialog.
141
River Network Editor
Catchment discharge can be calculated by the Rainfall Runoff Module and input as lateral inflows to the hydrodynamic module. The property page is used to specify the lateral inflow locations on the river network.
Catchment Definitions
Name: Name of input catchment.
Area: Catchment area.
Connection to Branches
Branch Name: Name of the river branch for catchment inflow.
Upstream and Downstream Chainage: The catchment inflow can be
uniformly distributed along a river branch by specifying the upstream and the downstream chainage. Inflow will occur at a single point in the case of equal upstream and downstream chainage.
Overview
The dialog supplies a tabular overview of the catchments.
2.6
Tabular View: Grid Points
142
Figure 2.75
Grid points dialog.
MIKE 11
Tabular View: Grid Points
Purpose
The page has two specific purposes:
1 The page presents summary information on the computational network
(or grid) points prior to the simulation.
2 The page can be used to limit the number of computational points saved in result files. (e.g. for large models it is desirable to save only those grid points required and to discard remaining results thus preventing result files from becoming too large).
The page has no influence on the simulation results and is only for information purposes (i.e. the user is not required to the press the Generate
Grid Points button prior to a simulation. However if changes are made to the model setup (e.g. the location of cross sections or the maximum deltax in a branch is altered) then the Generate Grid Points button can be pressed to update the tabular information presented.
All generated grid point information is displayed in the Graphical View of
the network. To view the grid point information in the graphical view you must ensure the correct options are selected in the Network Settings Dialog.
Control of Output
When reduced output is selected only those grid points highlighted with a check mark in the right hand side tree view, will be saved. The three levels in the tree view are model setup, model branch and model grid points.
These are described below.
Table 2.3
Level in tree view (right hand part)
Setup
Content of the list view (left hand part)
Branches: Total number of branches h:
Q:
Total number of h-points
Total number of Q-points h * :
Q * :
Total number of selected h-points
Total number of selected Q-points
River Network Editor
143
144
River Network Editor
Table 2.3
Level in tree view (right hand part)
Content of the list view (left hand part)
Filename.nwk
11
Branch
Name:
US Chn:
Name of the branch
DS Chn:
Chainage of the upstream end of the branch
Chainage of the downstream end of the branch
Branches
Length: h:
Length (m) of the branch
Number of h-points in the branch
Q: h * :
Number of Q-points in the branch
Number of selected h-points in the branch
Q * : Number of selected Q-points in the branch
Chainage: Chainage of the grid point. A check mark before the chainage indicates that the grid point is selected.
Type:
Data:
h or Q.
Several types of information are possible:
The “-“ symbol in an h-point row indicates that no cross section is present at this location (i.e. the h-point is generated by interpolation between neighboring cross sections to fulfil the maximum delta-x criteria).
The “-“ symbol in a Q-point row indicates this is a standard Q-point where the momentum equation is solved.
MIKE 11
Tool bars
Table 2.3
Level in tree view (right hand part)
Content of the list view (left hand part)
The word “X-sec” in an h point row indicates that a cross section exists at this location.
The word “Structure” in a Q point indicates that a structure is located at this location.
2.7
Tool bars
The graphical view is facilitated with two tool bars. One for graphical editing of the river network, and one for graphical editing of alignment
lines (see 2.2.3 Alignment Lines (p. 46) for more details about alignment
lines)
2.7.1
Tool Bar for River Network
The tool bar for graphical editing of the river network is shown in
Figure 2.76. In the following the functionality of each of the icons in the
tool bar is explained.
River Network Editor
Figure 2.76
Tool bar for editing river network
Select object. This icon activates the selection mode which is also
the default mode. Points, layers and other objects can be selected by pointing and clicking with the left mouse button. Multiple objects can be selected by moving the mouse to a corner of the area of interest, clicking and dragging with the left mouse button. Objects located within the marked area will be selected. Selected objects are identified by a red frame indicator.
Add new points. New points can be added by a point and click
operation using the left mouse button. Multiple points can be added by pressing the left mouse button and holding it down while moving the mouse along the desired path. New points will be cre-
145
146
River Network Editor ated with a spacing determined by the “minimum digitize distance” specified in the Mouse Settings property page of Network Settings. Points added with this tool will always be added as free points, i.e. not connected to a river branch. Alternatively you can add new points and define a river branch in one operation using the following tool.
Add points and define branch. This tool creates points and
branches in a single operation. Point and click at successive locations along a desired path. Points can also be added by pressing the left mouse button and holding it down while moving. Double click on the last point to end the branch.
Delete points. This tool deletes both free points and points con-
nected by a branch. Move the cursor over the point (the cursor will change style to indicate that a point has been detected) and press the left mouse button to delete. Multiple points can be deleted by holding the left mouse button down while moving the cursor over the points.
Move points. This tool moves both free points and points con-
nected by branching. Select the point using the left mouse button and then drag to the desired location.
Define branch. This tool creates one or more branches by draw-
ing a line through two or more free points. Select the first point to be included in the branch and drag the cursor through the free points to be included in the branch. Alternatively new points can be added in one operation by using the Add points and define branch
Auto route branch. This tool automatically determines a river
branch route from a set of free points. To use this tool you select the first point and drag to the last point on the branch. The editor automatically determines a path through intermediate free points by always searching for the closest point.
Delete branch. This tool deletes a branch without removing the
river points. Point at the branch to delete and click once with the left mouse button.
Cut branch. This tool divides a single branch into two separate
branches. Move the cursor to the required segment where the break is required. When the cursor changes style press the left mouse button once to cut the branch.
MIKE 11
Tool bars
Merge branch. This tool merges two separate branches into one.
Move the cursor to the beginning or the end of a branch, click at this point with the left mouse button and drag to the connection point on another branch.
Insert point. This tool will insert free points into an existing
branch. Move the cursor to a point on an existing branch, click with the left mouse button and drag the cursor to the free point for inclusion into the branch path.
Exclude points. This tool will exclude points connected along a
branch. Move the cursor over the point to be excluded and click the left mouse button once. The point is excluded from the branch path but is not deleted.
Connect branch. This tool is used to connect two river branches
at a junction point.Click and drag with the left mouse button from a river branch end point (upstream or downstream) to the junction point on a neighboring branch.
Care should be taken when connecting four or more branches. In such cases all branches connections should be made to a single junction point
Incorrect branch connection
Correct branch connection
River Network Editor
Figure 2.77
Connection of four or more branches.
Disconnect branch. This tool deletes a branch connection. Select
the point at the end of the branch to be disconnected and click with the left mouse button once.
Repeat insert. The repeat insert tool will add a copy of the latest
object (weir, cross section, boundary condition, initial condition etc.) created using the Insert facility in the Pop-Up Menu. The
147
River Network Editor repeat insert button is a fast and convenient way of inserting multiple objects to the river network. The current object type is shown in the status bar when the repeat insert button is activated. After activating the repeat insert tool you should point and click once at the desired location of the new object.
Select & edit. This tool is similar to the Edit facility found in the
Pop-Up Menu. The tool is a fast convenient way of accessing the various editors required for objects on the river network. To control the number of editor windows activated use the Select and Edit Settings Property Page of the Network Settings property sheet.
2.7.2
Tool Bar for Alignment Lines
The tool bar for graphical editing of the river network is shown in. In the following the functionality of each of the icons in the tool bar is explained.
148
Figure 2.78
Tool bar for editing alignment lines.
New alignment line.Add a new alignment line by pointing and
clicking at successive locations along a desired path. Points can also be added by pressing the left mouse button and holding it down while moving. Double click on the last point to end the line. Once added the line should be given the correct type and be connected to a branch.
Move alignment line points.This tool moves points on an align-
ment line. Select the point using the left mouse button and then drag to the desired location.
Delete alignment line points. This tool deletes points on an align-
ment line. Move the cursor over the point (the cursor will change style to indicate that a point has been detected) and press the left mouse button to delete. Multiple points can be deleted by holding the left mouse button down while moving the cursor over the points
Insert points to alignment line. This tool will insert free points
into an existing alignment line. Move the cursor to a point on an existing branch, click with the left mouse button and drag the cursor to the free point for inclusion into the branch path. The free point to be
MIKE 11
Tool bars inserted must be added using the tool “Add new point” in the available in the toolbar for river network editing.
Add points to alignment line. Using this tool you can add points
to an existing alignment line. Point are added at the upstream or downstream end. Click once at the point to which you want to add new points. Then point and click at successive locations along the desired path.
Spline alignment line. Splines an alignment line by automatically
adding new points in between the existing points. Once you have clicked at the icon in the tool bar, you should click once at the first point in the branch to be splined, then click at the last point. Points will be added only between the first and last point clicked at. The coordinates of
the existing points will not change a result of the splining. Figure 2.79
shows an alignment line before and after splining. Five points have been added between all existing points
Before splining
After splining
River Network Editor
Figure 2.79
Alignment line before and after splining.
Merge alignment lines. Merges two existing alignment lines into
one such that the properties for the merged line equals the properties of the first line. Click once at the downstream end of the first line, then click once at the upstream end of the second line, and the lines are merged.
Connect alignment line. Connects a new alignment line to a
branch. Click once at the alignment line to be connected, then click once at the branch the alignment line should belong to.
149
River Network Editor
Dead water line in vegetation. Adds a dead water zone behind a
vegetation zone (see Figure 2.16). The vegetation zone must be
connected to a branch before this tool is applied. Using this tool the should select (by clicking once) the two points along the vegetation zone at which the two dead water lines should start. Once the user has selected the two points the tool automatically finds the direction of the flow by finding the point on the branch which is closest. This defines the guide lines, and once the angle between the guide line and the dead water line is specified by the user, the dead water lines are created.
Dead water line along bank.Adds a dead water zone adjacent to
an expansion (see Figure 2.15). This tool is only available for
left/right levee bank alignment lines that has been connected to a branch. Using this tool the should select (by clicking once) the two points along the bank line at which the two dead water lines should start. Once the user has selected the two points the tool automatically finds the direction of the flow by finding the point on the branch which is closest. This defines the guide lines, and once the angle between the guide line and the dead water line is specified by the user, the dead water lines are created.
150 MIKE 11
C R O S S S E C T I O N E D I T O R
151
152 MIKE 11
Raw data View
3 CROSS SECTION EDITOR
The Cross Section Editor manages stores and displays all model cross section information.
There are two types of cross section data; the raw survey data and the derived processed data. The raw data describes the shape of the cross section and typically comes from a section survey of the river. The processed data is derived from the raw data and contains all information used by the computer model (e.g. level, cross section area, flow width, hydraulic/resistance radius). The processed data can be calculated by the cross section editor or entered manually.
Each cross section is uniquely identified by the following three keys: z
River Name: The name given to the river branch. String of any length.
z z
Topo ID: Topographical identification name. String of any length.
Chainage: River chainage of cross section (positive direction down-
stream).
Refer to one of the following sections for more Information:
3.2 Processed data view (p. 176)
3.3 Importing cross sections using File Import (p. 183).
3.4 Exporting cross sections using File Export (p. 188)
Some of the features related to the Steady flow with vegetation module are implemented in the Cross Section Editor. These have been developed in cooperation with CTI Engineering, CO., Ltd., Japan. This also includes moving points parallel or by distance, the version manager, and interpolation of raw cross section data.
3.1
Raw data View
The raw data view is the default and is displayed whenever a cross section
file is opened or created (see Figure 3.1).
Cross Section Editor
153
Cross Section Editor
Figure 3.1
The raw data view.
The raw data editor is made up by three views plus a number of additional dialog boxes: z z z
Tree view: Provides a list of all cross sections in the file. The list is dis-
played using a tree structure with three levels. The upper level contains river names, the second contains the Topo-IDs, and the third contains cross section chainage.
Tabular view: Selecting a cross section with the left mouse button will
display the section information in the tabular view.
Graphical view: An x-z-plot of the cross sectional data with markers
and vegetation zones indicated (the latter only for the quasi two dimensional steady state solver with vegetation).
3.1.1
Cross Section header data
River Name, Topo ID and Chainage
Non-editable information of the river name the topological identification tag and the chainage along the river. These values may be changed by selecting the appropriate level in the tree view using the rename facility
154 MIKE 11
Raw data View
Cross section ID
An identification tag may be entered here. This tag is subsequently displayed in MIKEView and does not influence the calculations.
Section Type
The type of section is set here. Four possibilities are listed:
– Open section: The typical setting for river cross sections.
– Closed irregular: Closed sections with arbitrary shape.
– Closed circular: Circular shape where only the diameter need to be given.
– Closed rectangular: Width and height is required.
Radius Type
The type of hydraulic radius formulation is set here. The choices are:
– Resistance Radius: A resistance radius formulation is used.
– Effective Area, Hydraulic Radius: A hydraulic radius formulation where the area is adjusted to the effective area according to the relative resistance variation.
– Total area, Hydraulic Radius: A hydraulic radius formulation where the total area is equal to the physical cross sectional area.
Resistance
Only used in conjunction with the quasi two dimensional steady flow with vegetation module.
The setting for the resistance column in the tabular view (see Figure 3.9).
Datum
A datum may be entered here which is added to all vertical coordinates in the tabular view.
Coordinates
Plan coordinates may be entered here for the left/right end of the cross section. If non-zero values are entered the values are used in the graphical view of the network to display the cross section width.
Cross Section Editor
155
Cross Section Editor
Correction of X-coor
This is used for determining the correction angle for the X-coordinates in the profile. The correction may be used for situations where the cross section profile isn’t perpendicular to the centre line of the river.
The correction angle can be automatically calculated from the river center line defined in the graphical network editor and the section plan coordinates by activating the ‘Calculate angle’ button. Note that this button requires that the simulation file is open, a network file and a cross section file are defined in the simulation editor and that georeferenced coordinates have been applied as described above.
The correction applied is simply a projection of the cross sectional profile on the normal to the thalweg of the river i.e. the correction reads
(3.1)
x
cor
=
x
cos
θ where
θ is illustrated below
Cross sectional profile
Thalweg
156
θ
Figure 3.2
Definition sketch of the correction angle.
Please note that the correction of X-coordinates is
Morphological Model
A level of diviside can be entered. This level of divide has two purposes:
1 To identify a level where flood plains and the main channel are seperating. This feature will be used in a morphological sediment transport simulation to distinguish from the morphological active main channel part from the flood plain part of the cross section where morphological changes does not occur. In the simulation an internal division in a main channel part and a flood plain part of the section will be made at the x-
MIKE 11
Raw data View coordinates corresponding to the Divide level z-value and eventual morphological changes will only be applied in the main channel part fo the section.
2 The second functionality of the Divide level is that it can be used for activating the flood plain Resistance feature in a hydrodynamic simulation, where a uniform resistance value can be applied in a section
above the level of divide as described and specified in section 6.4
Flood Plain Resistance (p. 301).
Resistance numbers
In this section of the raw data window the user chooses to how to deal with bed resistance. Two choices have to be made:
Transversal distribution
This defines description of the resistance across the cross section. There are three choices: z z z
Uniform: A single resistance number will be applied throughout the cross section
High/Low flow zones: Three resistance numbers are to be specified: 1)
Left high flow resistance applying between marker 1 and 4. 2) Right high flow resistance applying between marker 5 and 3, and 3) Low flow resistance applying between marker 4 and 5. If marker 4 and 5 do not exist the low flow resistance number will apply throughout
Distributed: The resistance number is to be specified for each X,Z data set.
Resistance type
There are the following choices for type of resistance number z z z
Relative resistance. The resistance is given relative to the resistance number specified in the .hd11 file (HD parameter file). Resistance numbers higher than one always corresponds to higher physical resistance than specified in the .hd11 file (i.e. independent of the choice of resistance number type in the .hd11file).
Manning’s n: The resistance number is specified as Manning’s n in the unit s/m (1/3) . Resistance numbers specified in the .hd11 file do not apply.
Manning’s M: The resistance number is specified as Manning’s M in the unit m
(1/3)
/s. Resistance numbers specified in the .hd11 file do not apply.
Cross Section Editor
157
Cross Section Editor z
Chezy number: The resistance number is specified as Chezy number in the unit m (1/2) /s. Resistance numbers specified in the .hd11 file do not apply.
3.1.2
Raw data, Tree View
The tree view presents the hierachy of cross sections in the cross section file grouped in a tree with river names as top level, Topo ID’s as secondary level and river chainages as the lower tree view level.
Selecting a river branch, Topo ID or cross section with the mouse and pressing the right mouse button will open context sensitive pop-up
menus with different functionality.
The following editing facilities are available from the context sensitiive pop-up menus:
Insert...
Once the ‘Insert...’ facility is selected from either the Branch, Topo-ID or
Section part of the tree view, the Insert branch dialog as presented in
Figure 3.14 is activated. Through this dialog it is possible to insert either a
new River Name, a new Topo-ID and/or a new sections defined by a chainage of a cross section.
Insert Interpolated
This feature is only available when activating the pop-up menu from the cross section/chainage level of the tree view. The cross section editor gives the user the possibility of inserting interpolated cross sections in a given set-up. When selecting this feature a seperate dialog appears.
158
Figure 3.3
The Insert Interpolated Cross section facility from the Raw Data,
Tree view.
MIKE 11
Raw data View
The user can either choose to interpolate a single cross section at a given chainage or multiple cross sections. In the latter case a maximum distance between the cross sections and also the range of the interpolation need to be specified.
Finally three tick boxes gives the user additional options: z
Calculate processed data: The processed data is calculated as the cross sections are created.
z
Extract cross section informations from river editor: Checking this the interpolated cross section will be updated with respect to marker positions and zone classifications according to the alignment line information in the network editor. Corresponds to the button called "Update
Zone Classification" in the raw data dialog.
Include existing interpolated cross sections in interpolation: This box should not be ticked in case the linear interpolations are to be based on the original data only.
Delete...
From the pop-up menu it is possible to delete either an entire river branch, a single Topo-ID within a river or a single cross section. Once activated, the delete-feature will present a confirmation message-box where the user must confirm the deleting of selected item by pressing Yes.
If one or more sections have been selected a different opiton dialog appears where the user must define whether the Delete action shall include e.g. only the selected sections within a branch or all of the sections within
that branch as illustrated in Figure 3.4.
Cross Section Editor
Figure 3.4
Delete sections option dialog from Raw data, tree view.
Rename...
It is possible to rename River names and Topo-ID’s or even rename/change the chainage of a section through the ‘Rename’ facility.
When activating the Rename dialog from the pop-up menu in one of the
159
Cross Section Editor tree view levels it is possible to change either name strings for the river name and/or Topo-ID or chainage-values for a river section, see
Figure 3.5
Rename feature dialog from Raw data, tree view.
Copy...
The Copy facility makes it possible to copy a single cross section, a Top-
ID or a an entire River branch to a different name/location. The copy dialog requests a Topo-ID, branch name and chainage before copying the cross section.
If one or more sections have been selected it must be selected in the Copy dialog whether the copy-function shall include all sections or only the
selected ones as illustrated in Figure 3.6.
160
Figure 3.6
Copy facility dialog from Raw data, tree view
MIKE 11
Raw data View
Combine...
The combine dialog is used to combine two river branches of the same name but with differing Topo-ID. The combination is saved as a new river branch of the same name and a specified Topo-ID. The facility is designed for combining cross sections at chainage locations where two sources of cross section data exist. The dialog which appears once Combine is
selected is presented in Figure 3.7 .
Cross Section Editor
Figure 3.7
Combine cross section profiles dialog from Raw Data, tree view.
A typical example occurs when combining survey (SUR) cross sections with digital elevation model (DEM) sections. A DEM is used to extract sections from broad flood plains while survey is used to obtain river sections. The combine feature will produce a composite section which can be saved under a new Topo-ID. z
Topo-ID of DEM profiles:
Topo-ID of the DEM or first sections. z
Topo-ID of SUR profiles:
Topo-ID of the SUR or second sections. z
Topo-ID of combined profiles:
Topo-ID of the combined sections. Section will only be created at locations with corresponding chainage. z
Maximal difference:
The Maximal difference is the tolerance limit within which sections are considered to correspond. z
Synchronize to:
161
Cross Section Editor
Specifies the method for combining sections. Currently only one
option is available: Centre (Mark 2) as illustrated in Figure 3.8.
162
Figure 3.8
Centre (mark 2) The plot shows a DEM section (indicated by the blue/dark dots) and a SUR section (indicated by the grey dots). The combined section will include the DEM section from x=0 to the left marker (the diamond) of the SUR profile, then the SUR profile to the right marker (third diamond from the left) of the SUR profile and finally the DEM profile for the remaining part of the section.
Select / Unselect
The tree view in the raw data dialog provides a feature for selecting cross sections. Most features such as deleting, renaming, copying, processing and plotting can be applied on either all cross sections in the file or on selected cross sections only. Cross sections which are selected are marked in the tree view with chainage in bold. Individual cross section can be selected in four ways:
1 Double-click on the chainage in the tree view.
2 <Ctrl>+click on the chainage in the tree view.
3 Press space bar while the chainage in the tree view is in focus.
4 Choose "Select/Unselect" in the pop-up menu
5 The pop-up menu at River name or Topo ID level in the tree view contains items for selecting or unselecting all cross sections in a River name or Topo ID.
MIKE 11
Raw data View
3.1.3
Raw data, Tabular view
The tabular view is only appropriate if the section type is set to open or to closed irregular and may in such a case consist of up to six columns given by:
X
This column contains the transversal coordinates of the raw data.
Z
The vertical coordinates of the raw data.
Resist.
This column is used for setting relative resistance.
In conjunction with the quasi two dimensional steady flow with vegetation module it is used for setting local values of Manning’s M or n. Depending
on the setting in the resistance combo box (see Figure 3.9).
Figure 3.9
Resistance combo box. This combo box is only visible if a Quasi two dimensional steady state solver with vegetation has been installed.
Mark
The column is used for setting the markers 1 to 9 plus possible user defined marks. Clicking an element in the column opens a marker dialog as shown below.
Cross Section Editor
Figure 3.10
Select marker dialog box.
A number of markers may be set in this dialog:
163
164
Cross Section Editor
– Left/right levee bank: Defines the extend or the active part of the cross section used for the calculations.
– Left/right low flow bank: Defines the extent of the low flow channel. Only used in conjunction with the quasi two dimensional steady flow with vegetation module.
– Left/right coordinate markers: Defines the points in the cross section corresponding to the coordinates used for determining the correction angle.
– Left/right channel bank markers: Defines the points in the cross section corresponding to extend of the main channel. The markers have an effect on the calculation of the processed data. For details consult the reference manual.
– Lowest point: The lowest point of the river may be set using this marker. The marker is used for post processing only and thus does not affect the calculations.
– User marker: Any number above 9 may be used as a user marker.
User markers do not impact the simulation results. They are an option for indicating a specific point in a cross section e.g. the location of the measurement gauge. To remove a user marker set the numeric value to 0 and deselect the apply flag.
Zone
This field and the following are only of concern in conjunction with the quasi two dimensional steady flow with vegetation module.
The type of zone is set here by clicking an element whereby a selection combo box is displayed with the following choices:
– Normal: A normal zone.
– Dead water: A user defined dead water zone.
– Vegetation zone: A vegetation zone not at the bank.
– Bank vegetation: A vegetation zone adjacent to the bank.
Please note that the calculation kernel of MIKE 11 does not allow vegetation zones to be defined on vertical sections. The simulation will terminate if this is violated.
Veg. h.
If a zone is set to either vegetation or bank vegetation this field becomes active. The vegetation height is set here and the average vegetation height for the corresponding panel is displayed in the graphical view.
MIKE 11
Raw data View
3.1.4
Raw data, Graphical View
The graphical view presents either a single plot of a selected cross section or eventually a number of plots from different sections (‘active’ and ‘passive’ cross sections). The graphical plot represents the values defined in the tabular view and eventual changes in the tabular view for a section is immediately presented graphically as well.
Toolbar icons
Two groups of toolbar-icons are available once the raw data graphical
view is activated, See Figure 3.11.
Cross Section Editor
Figure 3.11
Raw data Graphical view, Toolbar Icons
Listed from left the icons presented in Figure 3.11 are as follows:
– Zoom In : Enables zoom in of graphical view
– Zoom Out : Zoom out to full extent of all sections visible in view
– Previous zoom : Zoom to previous
– Next zoom : Zoom to next (active if Previous zoom has been activated one or more times)
– Draw Grid : On/Off switch for the drawing of a grid in view
– Undo : Undo facility for the last graphically edited point
– Select : Selector of point in the graphical view. When clicking on a point in the graphical view the line in the tabular view containing values for the actual point will be highlighted
– Move points : Moves a point in the graphical view. x- and z-values in the tabular view is automatically updated from the moving of the point.
– Parallel move : Moves a selected number of points graphically. To use this feature, first select a group of points by clicking at the first point to move and the last point to move. Thereafter the group of points within the selection can be moved by click and drag in the graphical view.
165
Cross Section Editor
– Insert points : Insert additional points in a section. By point to a line segment of a cross section and activating the insert points a new point will be inserted in between two existing points on that section reach.
– Delete points : Deletes points from the graphical view, and automatically points will be removed from the tabular view as well.
Right mouse pop-up menu
To control the settings and appearance of the graphical view, a number of facilities are available through a right mouse pop-up menu in the graphical view. To open the pop-up menu point to the graphical view with the mouse cursor and press the right mouse button. A pop-up menu as presented in
166
Figure 3.12
Raw data, Graphical view: Right mouse pop-up menu
The features included in the pop-up menu are as follows:
MIKE 11
Raw data View
– The first group of features are the zooming facilities. From here the zoom in, zoom out (to full extent!) and the previous zoom facilities as described under toolbar icons above can be activated (similar functionality as when an icon has been activated).
– The second group of features variable settings for the appearance of the graphical view.
These features are:
- Grid : Swithc for activating the grid on the graphical view
- Clear : Clears the view such that only the active section is pre-
sented and additionaly zoomes out such that the actual cross section uses the entire view.
- Move points by distance : A feature for enabling a moving of a group of points by a user-defined distance (in both x- and z-direction)
- Settings : Opens the Cross Section Settings dialog as described in
Section 3.1.7 below. Through this dialog the general appearance of
the graphical plot of sections can be modified (colours, point-type and -size etc.)
- Font : opens a seperate standard Font settings dialog where fonttype, -size and -colour can be modified.
– The third group of features are different facilities for making graphical editing of the cross section raw data. The facilities include,
Select points, Move points, Move points parallel, Insert points and
Delete points. This list of facilities is identical to the graphical editing toolbar icon facilities as described above. Similar functionlity if a feature is activated through the pop-up menu as compared to activating a toolbar icon.
– The last group of features in the menu is a version manager facility as described in more detail below.
Version Manager
The version manager is a facility which enables a storing of multiple versions of one or more cross sections. It is possible through the version manager to save different versions of the same cross section which eventually undergoes different changes in e.g. a design-optimisation project.
Cross Section Editor
167
Cross Section Editor
Figure 3.13
Version manager, Raw data graphical view
The version manager as presented in Figure 3.13 saves the different sec-
tions in a tree-view format which enables the user to keep track of different changes the section has undergone. The Version manager data can be saved to an Ascii file by use of the ‘Save’ buttons - and can be re-loaded by the ‘Load’ buttons.
3.1.5
Additional features of the Raw Data editor
Additional tick boxes
At the bottom left corner of the editor two tick boxes are present.
Synchronize processed data
By ticking this box the processed data and raw data views are synchronized i.e. if both views are open the data displayed corresponds to the same cross section.
Update processed data automatically
Ticking of this box ensures automatic updating of processed data for all sections that are activated in the raw data tree view.
Additional buttons
Insert cross section
Pressing this button activates a pop up dialog as shown below.
168 MIKE 11
Raw data View
Figure 3.14
The Insert branch dialog.
In this dialog the appropriate information for a new section in a new or existing river branch must be specified and thereafter press OK.
View processed data
This button opens the seperate processed data view.
Update zone classification
Only used in conjunction with the quasi two dimensional steady flow with vegetation module.
Used for updating the zone classifications in the cross section.
3.1.6
‘Cross-sections’ pull down menu
When the cross section editor is active the cross section pull down menu may be activated. This menu has two items:
Info
Update markers
This button updates markers 1, 2 and 3 in the actual section as the extremes of the cross section (left bank limit, lowest point and right bank limit respectively). Note, that this facility overwrites eventual user defined settings of these three markers unless the appropriate boxes under Settings
–> Cross section.... –> Update Markers have been unticked.
This simply gives an overview of data in the cross section data base: z z z z
Number of Rivers
Number of Topo IDs
Number of cross sections in actual Topo ID
Number of X, Z in actual profile.
Cross Section Editor
169
Cross Section Editor
Apply to all sections
This option activates a dialog with a number of options see Figure 3.15.
170
Figure 3.15
Apply to all cross sections dialog
To change any of the crpss section parameters listed in this dialog the respective ‘change’ tick box must be selected.
Raw data - Radius Type
The user can choose to change the radius type of all cross sections in the set-up.
Raw data - Datum
The global datum can be changed here.
Raw data - Section Divide
A global level of divide can be set here.
MIKE 11
Raw data View
Cross Section Editor
Raw data - Resistance Type
The global resistance type, transversal distribution or resistance values may be changed using this facility.
Processed data - Level selection method
The global settings for the selection of the water levels used for calculating the processed data may be set here.
Processed data - Number of levels
The global number of levels used for determining the processed data is set here.
Chainages. With this option the chainages for cross section can be
changed by a multiplier (C1) or a constant can be added (C2). Using C1=-
1 and C2 as the existing maximum chainage will swap the chainage direction and the chainage values from upstream to downstream.
Invert left and right. This will swap the X/Z data and markers left from
right.
Markers. With this option you can delete slected markers or change the
position of selected markers. Choosing the latter will bring up three choices for how to move the markers.
1 1, 3: Left/right most, 2: Lowest. This will place marker 1 and 3 (if selected) in the left most and right most point respectively. Marker 2 will be placed in the lowest point.
2 1, 3: Left/right levee, 2: Lowest. This will place marker 1 and 3 in the left levee and right levee respectively. The left levee is found by starting from the lowest point and search to the left until a point is found where the next point is lower by more than the minimum Z decrease specified. Similar for the right levee. Marker 2 will be placed in the lowest point.
3 1, 3: Left/right most, 2: Lowest, 4,5: Left/right levee: This is a combination of the first two choices. Marker 1 and 3 will be placed in the left most and right most points respectively and marker 4 at the left and right levees. Marker 2 will be placed in the lowest point.
Action to be done
A number of options to be applied to all the cross sections in the set-up are available: z
Update zone classification.
171
Cross Section Editor z z
Update correction angle.
Recompute all.
Apply to Selected Sections
Activating this feature enables the same possibility for modigying cross section parameters as listed above in the ‘Apply to all sections’ but the adjustments will only be performed on sections selected in the tree view.
Please note that applying any of the above will overwrite any user edited
settings/data. There is no undo feature so make sure to save the cross section data before activating the OK button.
Resistance Number Interpolation...
When calibrating/changing resistance numbers in a large number of cross sections where resistance number distribution is high/low flow zone or uniform, it may be feasible to use this tool to interpolate resistance numbers. The tool works such that the user specifies the resistance number at a number of locations and when pressing the OK button the resistance numbers in all cross sections between specified locations will be linearly interpolated.
The information in the resistance number interpolation table is saved in a separate file with the same name as the cross section file, but with extension .xns11r. This is an ASCII file in PFS format. In this way the auto calibration tool can be used to calibrate resistance numbers in cross sections.
3.1.7
‘Settings’ pull down menu
Cross Section settings; Graphics
The graphics settings consists of a tree structure view of all possible settings for the graphical elements of the cross section editor, see
Figure 3.16. The desired elements are ticked and the properties are set
using the right hand side of the dialog box.
172 MIKE 11
Raw data View
Figure 3.16
Settings -> Cross Sections.dialog, Graphics page
Cross Section Settings; Drawing
Cross Section Editor
Figure 3.17
Settings -> Cross Sections dialog, Drawing page
A number of settings are available (Figure 3.17):
173
174
Cross Section Editor
Draw GIS marks: Marks the locations on a cross section where data has
been extracted from GIS images.
Draw history: Creates a watermark as a history of previous cross sections
drawn on the graphical view. The current cross section and previous cross sections can be presented in different colours dependent on settings in the
Graphics dialog page. This feature allows comparison of multiple cross sections on a single scale.
Automatic rescale: Automatic re-scaling of the graphical view when raw
data is being displayed. This prevents plotting of cross sections outside of the display area.
Allow global selection: Allows previous cross sections displayed as
watermarks to be selected from the graphical view using the mouse pointer. If this function is off, the mouse pointer will only select from the current cross section displayed in black.
Drawing style
The drawing style controls the Z axis display in the graphical view. There are three options available:
1 Absolute Including Datum: The displayed Z values include the datum factor.
2 Absolute Excluding Datum: The displayed Z values exclude the datum factor.
3 Relative to Bottom: The Z values are displayed relative to the lowest point in the cross section regardless of the datum. (i.e. all cross sections will be displayed with the lowest point set to 0 metres.).
Axis label
The axis label feature allows for user-defined axis labelling and selection whether the graphical plot should include units or not.
Resistance scale
The resistance scale option defines whether a fixed or automatic scaling of the Resistance axis is presented. In case of a fixed scale selected, the minimum and maximum value of the axis scale must be defined.
Cross Section Settings; Miscellaneous
The Miscallanous page contains different options for the graphical and
tabular view, see Figure 3.18.
MIKE 11
Raw data View
Cross Section Editor
Figure 3.18
Settings -> Cross section dialog; Miscellaneous page
Checks
A feature for checking raw data to ensure that sections are open or closed.
If data does not pass the chosen check-option then a message will occur.
Overall Radius setting
The default setting of the radius type may be altered here.
Confirmations
The user can specify whether a confirmation dialog box should appear when deleting points or clearing history in the graphical view.
Align
A snap to grid feature in the cross section editors graphical view.
Default Resistance in Raw Data
Used for defining which of the default type and value of the resistance column in the tabular view of the cross section editor. Default values are applied when a new cross section is inserted.
175
Cross Section Settings; Update Markers
Cross Section Editor
Figure 3.19
Settings -> Cross Sections dialog; Update Markes page
This dialog is used for defining which of the markers 1, 2 and 3 should be automatically updated. Only the selected markers in this dialog will be updated by eventually adjusting its position in a cross section when activating the update markers button.
3.2
Processed data view
Selecting the View Processed Data button on the Raw data View (p. 153)
activates the processed data view.
Note that when utilizing the quasi two dimensional steady state with vege-
tation module the processed data does not reflect the values used in the calculation. In the calculation kernel of this module the X, Z - coordinates of the individual cross sections are used for determining the hydrodynamic parameters of the individual panels.
The processed data view is similar to the raw data display. A tree view exists on the left where the required cross sections can be selected. A tabular view provides all processed data and a graphical view on the right
hand side displays the processed data graphically (see Figure 3.20).
176 MIKE 11
Processed data view
Figure 3.20
The processed data view.
3.2.1
Processed data, Tree View
Selection of cross sections to view/analyse by use of the mouse. No context sensitive pop-up menus are available in the processed data tree view as all modifications to the cross sections in terms of naming, location etc. all must take place in the Raw data editor.
3.2.2
Processed data, Tabular View
The processed data is calculated from the raw data and contains the following parameters as presented in the tabular view:
Level
The level in the cross section. The calculation levels can be manually set using the Levels Dialog activated by the Levels button.
Cross section area
Effective Cross sectional flow area.
Radius
A resistance or hydraulic radius depending on the selected type. (Selection is made in the raw data view.)
Storage width
Top/Storage width of the cross section.
Cross Section Editor
177
Cross Section Editor
Add. storage area
The surface area of additional storage to be added at a cross section. This is useful for representing small storage’s associated with the main branch such as a lakes, bays and small inlets. Additional storage areas are always user-defined - they will never be given a value from the automatic processing of the raw data.
Resistance factor
This factor can be used to apply a variable resistance for incremental levels of flow height in the section cross section.The roughness parameter in
the Bed Resistance (p. 304) Property Page of the Hydrodynamic Editor
(p. 293) is multiplied by the resistance factor.
It is important to notice here, that this factor is always multiplied to the resistance value defined in the HD Parameter Editor. Dependent on the type of resistance number applied it is therefore important to be careful when editing the resistance factor values. Since they are multiplied to the resistance number these factors must decrease to values smaller than one in order to increase resistance if Manning’s M type of resistance number is applied. However, if Manning’s n (=1/M) is applied then it is required to define resistance factors higher than one to activate an increase in resistance with depth.
Conveyance
Conveyance is not used in the simulation but is displayed for the purposes of checking that the conveyance relationship is monotonously increasing with increasing water level.
Note that this may not be the case for closed sections or in some instances
of sudden width increase in the section geometry when using the hydraulic radius option.
3.2.3
Processed data, Graphical View
The graphical view presents a specific item of the processed data table as a water level curve dependent graph.
Toolbar Icons
A set of toolbar icons are acitve with the graphical view, see Figure 3.21
Figure 3.21
Toolbar Icons for Processed Data, graphical view
178 MIKE 11
Processed data view
Listed from left the icons presented in Figure 3.11 are as follows:
– Zoom In : Enables zoom in of graphical view
– Zoom Out : Zoom out to full extent of all sections visible in view
– Previous zoom : Zoom to previous
– Next zoom : Zoom to next (active if Previous zoom has been activated one or more times)
– Draw Grid : On/Off switch for the drawing of a grid in view
Right mouse pop-up menu
As in all other graphical views and editors in MIKE 11 a right mouse popup menu is available with a number of facilities present.
Cross Section Editor
Figure 3.22
Right mouse pop-up menu for Processed data, Graphical view
The features included in the pop-up menu are as follows:
179
180
Cross Section Editor
– The first group of features are the zooming facilities. From here the zoom in, zoom out (to full extent!) and the previous zoom facilities as described under toolbar icons above can be activated (similar functionality as when an icon has been activated).
– The second group of features variable settings for the appearance of the graphical view.
These features are:
- Grid : Swithc for activating the grid on the graphical view
- Clear history: Clears the view such that only the active graph is
presented and additionaly zoomes out such that the actual cross section data graph uses the entire view.
- History enabled: Enables the drawing of multiple sections in the view which scrolling the different sections in the tree view. If this ie switched off then alwaysonly one graph will appear in the view.
- Font : opens a seperate standard Font settings dialog where fonttype, -size and -colour can be modified.
Graphical plot items selector
It is possible to present view the graphical plot of any of the different hydarulic parameters listed in the tabular view columns. From a selection box in the top of the graphical view the requested data-type for presenta-
tion in the plot can be selected as illustrated in Figure 3.23.
MIKE 11
Processed data view
Figure 3.23
Drop-down selection box for plot of processed data types
3.2.4
Processed Data, Levels button
When activating the ‘Levels...’ button a ‘Levels for Processed Data’ dia-
Cross Section Editor
Figure 3.24
Processed data, Levels... dialog
181
182
Cross Section Editor
The Levels dialog controls the method for calculating processed data in sections as well as user-defined indications for number of processed data levels as well as eventual definitions of minimum and maximum levels in the processed data.
Level Selection Method
There are three methods by which the levels can be selected:
1 Automatic: The levels are selected automatically. If the resistance radius is applied the levels are selected according to variations in section flow width. If hydraulic radius is applied the levels are selected according to variation in the section conveyance.
2 Equidistant: The levels are selected with equidistant level difference.
3 User defined: The levels can be fully or partially selected. The selected levels are entered to the levels table on the dialog. If the number of defined levels is less than required by the Number of Levels specification the remaining levels will be selected automatically.
Minimum Level
The minimum calculation level. (The default is the lowest point in the section).
Maximum Level
The maximum calculation level.
Number of Levels
The desired number of calculation levels. The automatic level selection method may not use the full number of level specified. This will occur when a fewer number of levels is sufficient to describe the variation of cross sectional parameters.
A minimum of two levels is required. There is no upper limit to the number of levels.
Table of Levels
This section of the dialog is only applicable if the level selection method is user defined. The required levels are entered into the table manually. Levels can be added by pressing the Tab key while positioned at the bottom of the table. Levels can be deleted by selecting the row number and pressing the Delete key.
MIKE 11
Importing cross sections using File Import
3.3
Importing cross sections using File Import
Via File –> Import it is possible to read cross-section data (raw or processed) from a text file into MIKE 11.
The read facilities can be used to read cross-sectional data stored in an external data base format. The cross-sections are then read in via a temporary text file created as a medium between the external data base and the
MIKE 11 data base.
From the text file MIKE 11 can load the data and change them to MIKE
11's internal data base format. The text file formats must correspond to one of two types, depending on whether raw or processed data is to be read.
3.3.1
Import Raw Data
Selecting File –> Import –> Import Raw Data it is possible to import raw data into MIKE 11’s cross section data base. The File format must conform to the following format:
Cross Section Editor
Figure 3.25
File format of ASCII file used for importing data into MIKE11.
In Figure 3.25 topo idis to be understood as the topological identification
tag of the river. River name is self explanatory, the chainage should be entered in meters. The coordinates of the centrepoint of the cross section may be entered here for use in the network editor, if this is not required
183
184
Cross Section Editor zero should be entered. The flow direction is set to one if the positive flow direction is to be entered else it is set to zero, again this is only for use if the information is to be imported into the network editor. The datum is entered in meters and the type of radius used is set.The DIVIDE X-section is either set to OFF (0) or to ON (1) if the latter is the case the level of divide should be entered in meters proceeding the switch indicator. The cross-sections topological identification tag follows. The section INTER-
POLATED is set to OFF(0) or ON(1). If a correction angle of the cross section is to be used this may be entered here. After PROFILE the number of points (n) in the cross section should appear. Following this a table of values of X, Z, r r
and markers are required.
X x-coordinate
Z z-coordinate r r relative resistance
The markers are set according to:
<#1>
<#2>
<#4>
<#8>
<#16>
<#32>
<#64>
<#128>
<#256>
marker 1
marker 2 marker 3 marker 4 marker 5 marker 6 marker 7 marker 8 marker 9
Note that if a point has two or more markers the number after # is found as
a summation, for example:
<#6> indicates that the point represents marker 2 and 3.
Markers 4-7 are only of concern for the quasi two dimensional steady state with vegetation module.
Each type of information must start with an explanatory text line followed by one or more lines containing numerical information. This text line must start with three fixed characters, depending on the type of data:
MIKE 11
Importing cross sections using File Import z
Horizontal coordinates
Text line: Coordinates
Numerical line: 1 27.43 13.293
"0": The rest of the line will be ignored.
"1": The x- and y-coordinates will follow.
"2": The x
1
, y
1
and x
2
, y
2
coordinates of the section ends follow z
Positive current direction
Text line: Flow direction
Numerical line: 1 270
"0": The rest of the line will be ignored.
"1": The direction will follow z
Datum adjustment
Text line: Datum
Numerical line: (-)12.22
The datum adjustment will be added to the z-coordinates from the profile z
Closed section
Text line: Closed section.
If this text line does not occur the section will be taken as open z
Radius formulation
Text line: Radius type
Numerical line: 0
0 - Resistance radius
1 - Hydraulic radius using effective area
2 - Hydraulic radius using total area
Cross Section Editor
185
Cross Section Editor
The default is 0 (Resistance radius) except for closed sections, where the default is 2.
z x-z coordinates
Text line: Profile
Numerical lines: At least three lines containing corresponding values of x and z and optionally the relative resistance and/or markers. If the relative resistance is omitted 1.0 will be used. The x-values must always be increasing except for a closed section. z
End of a cross-section
Text line: ****************************
Small or capital letters can be used. It is optional to specify the above information except the x-z coordinates (profile).
There are no limits on the number of cross-sections allowed in the text file. Numbers can be entered in a 'free format'; i.e. with any number of decimal places.
If there is an error in the text file, the loading will be terminated and information will be given regarding the erroneous line.
If data for a particular cross-section already exists in the data base, the data in the text file will be ignored.
Selecting File –> Import –> Import Raw Data and Recompute it is possible to import raw data into MIKE 11’s cross section data base and recompute the processed data automatically.
3.3.2
Import Processed Data
Selecting File –> Import –> Import Processed Data it is possible to import processed data into MIKE 11’s cross section data base. The configuration of a text file containing processed data must conform to the following format:
186 MIKE 11
Importing cross sections using File Import
Figure 3.26
Format used for importing processed data.
The first three lines are as for raw data: Topo-ID, River Name and River
Chainage. As for raw data format, it is hereinafter possible to specify information about: z z z horizontal coordinates (as for raw data) positive current direction (as for raw data) processed data
The explanatory text line (see raw data) initiating the processed data must start with PROCESSED DATA. After this line, two text lines (headings), followed by M (number of levels) lines with the hydraulic parameters can be specified. The processed data for each cross-section must finish up with a line containing: *********.
Selecting File –> Import –> Import and overwrite Processed Data it is possible to import processed data into MIKE 11’s cross section data base and overwrite the existing processed data. This facility is often used if for example additional storage areas have been added to the processed data and these data are copied into another data base.
3.3.3
Import Coordinates of Levee Marks
Selecting File -> Import -> Import Coordinates of Levee Marks it is possible to import X, and Y coordinates for right and left levees into MIKE 11’s cross section database.
The format of the ASCII text-file containing Levee marks coordinates is:
River Name, Topo-ID, Chainage, Left X, Right X, Left Y, Right Y (items
Cross Section Editor
187
Cross Section Editor can be divided by 2 or more spaces or 1 or more tabs). One line for each series of coordinates.
Example:
--
--
Donau<Tab>2005<Tab>0.00<Tab>LeftX1<Tab>RightX1<Tab>LeftY1<Tab>RightY1
Donau<Tab>2005<Tab>750.00<Tab>LeftX2<Tab>RightX2<Tab>LeftY2<Tab>RightY2
Donau<Tab>2005<Tab>2000.00<Tab>LeftX3<Tab>RightX3<Tab>LeftY3<Tab>RightY3
3.4
Exporting cross sections using File Export
Via File –> Export it is possible to write cross-section data (raw or processed) from the MIKE 11 data base to a text file.
There are three possibilities:
1 Export All...: Both raw and Processed data is exported to a text file.
2 Export Raw...: Only the raw data is exported to a text file.
3 Export Processed...: Only processed data is exported to a text file.
3.5
Plotting Multiple Cross Sections
In addition to printing the actual content of the graphical view of the raw data dialog using File->Print... a feature for multiple cross sections plots is available.
To use this feature make sure that:
1 One or more cross section is selected.
2 Click in the graphical view (such that in comes in focus).
Now, one of following items in the File menu relating to multiple cross section plotting becomes available:
Print Multiple Cross Sections...
If the output device is selected as the printer in the settings dialog, this will open the print dialog. If a metafile is selected as output cross sections plots will generated in metafiles and no dialog will appear.
188 MIKE 11
Plotting Multiple Cross Sections
Print Multiple Cross Sections, Preview
This will open a preview dialog allowing the user to inspect the result of the settings or to view the cross sections on screen rather than in hard copy. Using <Page Up> and <Page Down> will jump to the next and previous page with multiple cross section plots.
Print Multiple Cross Sections, Settings...
This will open the dialog with settings for the multiple cross section plot-
Cross Section Editor
Figure 3.27
Dialog with settings for multiple cross section plotting
The settings dialog allows for controlling the following:
Nb. of plots on each page.
Each page is composed by number of individual cross section plots ordered in rows and columns. The user specifies the number of plots in the vertical and the horizontal direction.
Margins
The horizontal and vertical margins and the horizontal and vertical distances between the plots can be controlled in this section.
189
190
Cross Section Editor
Horizontal and vertical scale options
The horizontal and vertical scale options are equivalent. In the following the horizontal scale options are explained.
Automatic and individual on each section:The minimum and maximum
of the axis is selected automatically corresponding to the minimum and maximum values in each data set.
Fixed for all sections: User defined values for minimum and maximum of
the axis will be applied for all cross section plots.
Automatic minimum and fixed width:All cross sections will be plotted
on an axis with the same width (maximum minus minimum). The minimum value of the vertical axis will change for each plot according to the minimum value in the data set.
Fixed scale: The scaling of the axis will be selected according to the user
defined ratio between the physical cross section size and the printed size.
I.e. all cross sections will be plotted on an axis with the same width (maximum minus minimum). The minimum of the scale can be controlled as either a fixed offset below the data minimum for each cross section or as a fixed value applied for all cross sections.
Design profile
Each plot will normally contain one cross section data set. However, selecting this option it is possible to have another data set from the same location (river name and chainage) drawn in each plot. The Topo ID for the second cross section to be drawn is specified by the user. The second cross section will be drawn using the graphical settings for “passive” cross sections, and a legend for both cross section lines can optionally be drawn.
Output
The plots can either be routed to the printer or saved as meta graphics in a number of metafiles. Each metafile can only contain one page. I.e. the number of selected cross sections requires more than one page several metafiles will be written. The file names are generated automatically by adding _01, _02, _03 and so on to the file name specified by the user.
MIKE 11
B O U N D A R Y E D I T O R
191
192 MIKE 11
Users Upgrading from MIKE 11 Version 2002 or Previous Versions
4 BOUNDARY EDITOR
The boundary editor is used to specify boundary conditions to a MIKE11
Model. It is used not only to specify common boundary conditions such as water levels and inflow hydrographs but also for the specification of lateral flows along river reaches, solute concentrations of the inflow hydrographs, various meteorological data and certain boundary conditions used in connection with structures applied in a MIKE 11 model.
4.1
Users Upgrading from MIKE 11 Version 2002 or Previous
Versions
In version 2003 the layout of the boundary editor has been improved to make the specifications of boundary conditions easier and more intuitive.
The major changes are: z z z z
HD, AD and ST boundaries need no longer to be specified on different property pages in the boundary editor;
The user can now choose between various boundary descriptions: open boundary, a point source, a distributed source, a globally applicable boundary, a closed boundary or a boundary related to certain structures.
The user can now describe all boundary conditions attached to a specific location once. For example when applying the Advection-Dispersion (AD) Module the combined flow and concentration data are specified together;
Constant boundary conditions can now be specified without the need to create a time series (.dfs0) file.
z z
Boundary input time series may be scaled within the boundary editor.
Downstream Q-h boundaries can be automatically computed assuming critical or uniform flow conditions.
z
When undertaking AD simulations, it is no longer necessary to specify the type of boundary in the AD editor file.
Before running a model developed with the MIKE 11 2002 version or older the old boundary file needs to be converted to the new file format.
The conversion will start automatically when the old boundary file is opened in MIKE11. When converting it is necessary to browse for the relevant network file from which the necessary data needed for specifying the boundary type are stored. If the old boundary file contains any AD boundaries it is also necessary to specify the associated AD11file (AD
Boundary Editor
193
Boundary Editor parameter file) since the information regarding the type of AD boundary previously stored in this AD11 file must be transferred to the new boundary file.
4.2
Overview of the Boundary File
Figure 4.1 shows the initial layout of the boundary file when opened for the first time in an application. It consists of three split windows.
The top split window is used to specify the overall boundary conditions.
Each boundary condition appears as a row in a Boundary Table in this window. The table lists all boundaries included in a model set up. There is no limit to the number of rows (boundaries) that can be included in the table.
The contents of the second and third split windows depend on the specifications of the active row (row number highlighted) in the Boundary Table.
Additional information needed in order to specify the boundary conditions are entered in the second and third split windows.
Figure 4.1
Layout of the boundary file when opened for the first time in an application. Note that the third split window is empty.
4.2.1
The Boundary Table - Upper Split Window
The Boundary Table shown in the first split window gives an overview of the boundaries included in the model set up. The information required is the Boundary Description, the Boundary Type and the Location of the boundary. In addition a Boundary ID can be entered, although this is optional. Specifying an ID can be convenient for identifying the boundary, but it has no effect on the calculation.
194 MIKE 11
Overview of the Boundary File
Select the actual Boundary Description and the Boundary Type by placing the cursor at the right end of the edit field in question and left-clicking the mouse. A drop-down list appears from which the appropriate type can be selected, see figure 4.2.
Figure 4.2
Drop down list belonging to the Boundary Description
To insert new boundaries (rows in the Boundary Table in the first split window) press the “Insert” button on the keyboard or use the Tab key. A boundary (row) can be moved up or down in the table by selecting a row
(clicking in the left column) and dragging to the desired row. It is also possible to sort the boundaries alphabetically by double clicking the column headers. This operates for all the column headers in the first split window.
The Boundary Description describes the nature of the boundary (see Figure 4.3). There are six different types of Boundary Description: z z z z z
Open;
Point Source;
Distributed Source,
Global;
Structures; z
Closed.
These are explained in detail below.
The Boundary Type specifies the kind of data required for the boundary.
For each Boundary Description there are a number of valid Boundary
Types. Once a Boundary Description has been selected only the valid choices of Boundary Type are displayed. There are a total of 23 possible combinations of Boundary Description and Boundary Type, as shown in
Figure 4.3.
Boundary Editor
195
Boundary Editor
Figure 4.3
Possible combinations of Boundary Description and Boundary Type
4.2.2
Specifying the Boundary Description
A description of the options available in the Boundary Description column of the Boundary Table is given in the following.
The Open Boundary
An Open Boundary can be specified at the free upstream and downstream ends of the model domain. When the Open option is selected in a Bound-
ary Description cell, a branch name and chainage are also needed in order to identify the location of the boundary. An Open boundary condition has the following valid Boundary Types: z z
Inflow is specified when a time-varying or constant flow hydrograph condition (for the HD model) is required with or without a solute component (for the AD model);
Water Level is specified when a time-varying or constant water level
(for the HD model) condition is required with or without a solute component (for the AD model);
196 MIKE 11
Overview of the Boundary File z z z z
Q-h is specified when the relationship between the discharge and the water level (HD model) is known and used with or without a solute component (used in the AD model);
Bottom Level is specified for ST models, where the variation of the bottom (river bed) level is required as a function of time;
Sediment Transport is specified for ST models, when a variation of the inflow of sediment is required as a function of time;
Sediment Supply is specified for ST models, when neither the bottom level nor the sediment transport is known. Instead the inflow of sediment is computed as equal to the sediment transport capacity. No other information is needed for this type of boundary.
The Point Source Boundary
The Point Source boundary condition is used at locations within the model domain where time-varying or constant lateral inflows (or outflows) occur. When the Boundary Description is selected as Point Source a branch name and a chainage are required to identify the location. A Point
Source Boundary Description has the following valid types of Boundary
Type: z z
Inflow is specified when a time-varying or constant lateral inflow condition (for the HD model) is required with or without a solute component (for the AD model);
Sediment Transport is specified for ST models, when a variation of the lateral inflow of sediment is required as a function of time;
The Distributed Source Boundary
The Distributed Source boundary condition is used along river reaches within the model domain where time-varying or constant lateral distributed inflows (or outflows) need to be specified, or where meteorological boundaries apply. When the Boundary Description is selected as Distrib-
uted Source a branch name and two chainages need to be specified. The two chainages represent the up- and downstream ends of the river reach along which the distributed boundary applies. The order in which the chainages are specified is not important. The Distributed Source Boundary Description allows the following Boundary Types: z
Inflow is specified when a time-varying or constant lateral inflow condition (for the HD model) is required with or without a solute component (for the AD model). The inflow will be divided equally between each computational h-point lying in the specified chainage range;
Boundary Editor
197
Boundary Editor z z z z z
Evaporation is specified in river reaches where loss of water by evaporation affects the water balance (HD model). Evaporation can also be specified globally.
Rainfall is specified in river reaches where the inflow of rainfall affects the water balance and where any rain borne components affect the AD modelling. Rainfall can also be specified globally.
Heat Balance is specified when the advanced heat balance module is activated. Three different boundaries must be specified: The temperature, the relative humidity and the solar radiation. Heat Balance can also be specified globally.
Resistance factor is specified when a time varying resistance factor applies along a river reach. Resistance Factor can also be specified globally.
Wind Field is specified when wind induced stress on the surface needs to be accounted for. Two boundaries must be specified: The wind velocity and the wind direction. The direction of the wind is in degrees in clock wise direction from north, see figure 4.4. Inclusion of wind shear stress in the computation is specified in the Hydrodynamic
Parameter file (.HD11). The user can reduce the effect of the wind shear stress by applying a topographical wind factor in certain reaches in the .HD11 file. Wind Field can also be specified globally.
198
Figure 4.4
Definition of wind direction
MIKE 11
Overview of the Boundary File z
Groundwater Head is to be specified when the groundwater leakage
option (Groundwater Leakage (p. 328) ) in the HD editor is selected.
The groundwater head can be specified in three ways as follows:
1 As a constant in time and space and thus valid through out the model domain.
2 As a time series constant in space.
3 Constant in time and distributed in space with a 2D grid file.
The Global Boundary
The Global boundary condition is applied when a certain boundary conditions are valid over the entire model domain. In such cases it is not necessary to specify any location. The valid Boundary Types are: Evaporation;
Rainfall; Heat Balance; Resistance Factor and Wind Field. These Boundary Types are used in the same manner as Distributed Sources.
It is possible to specify both a globally applicable boundary condition and a distributed boundary condition of the same Boundary Type. The global boundary will be applied over the entire model except at those locations where distributed boundaries have been specified.
Figure 4.5 shows an example in which both global and local wind boundaries are applied. The globally defined wind stress will be applied all over the model except in the branch Main between chainage 0 - 10000 where a different time series (wind speed and direction) has been applied
Boundary Editor
Figure 4.5
Example of the application of both global and local boundary conditons.
EU functions. This Boundary Type can only be used as a global boundary and is used for eutrophication models. Two boundaries must be specified:
Temperature and solar radiation.
199
Boundary Editor
The Structures Boundary
The Structures boundary condition can be used in combination with three different Boundary Types: z z
Dam is specified when a discharge time series must be applied at the end of a stratified branch (MIKE Reservoir model). Besides the discharge boundary it is also necessary to specify the level, width and height of the extraction point. (This is done in the third split window.)
Dam Break is specified for time varying conditions in connection with a dam break. Three boundaries must be specified: The Dam Breach
Level, the Dam Breach Width and the Dam Breach Slope; z z
Regulating Structure, is specified to describe the discharge at a regulating structure.
NWS DAMBRK Piping, is specified to describe the temporal development of a dam breach using the NWS piping breach equation. The second dam breach level (fouth parameter) to be specified is the top level of the pipe. Once the pipe collapses the top level is neglected in the simulation and the three remaining parameters will be used for describing the trapezoidal breach.
For all four types the location must by specified by giving a branch name and a chainage. For the Dam Break, NWS DAMBRK Piping and the Regulating structure a structure ID must also be given.
Please note that the temporal development of a dambreak must be specified in a time series file with relative time axis. Further please ensure that the extent of this file covers the full the simulation period.
When using the NWS methods the terminal breach level is defined by the last value in the corresponding time series.
The Closed Boundary
The Boundary Description Closed is used at free ends points of the model domain where a zero flux condition across the boundary is applicable. It can be used for HD, AD and ST simulations. For the HD model it corresponds to a zero discharge boundary and for AD and ST models it corresponds to zero transport across the boundary. No additional information is required except the location described by branch name and a chainage.
4.2.3
Specifying the Boundary Type, Data Type and File/Values
In this section the specification of the Boundary Type and associated Data
Types are described. This additional information is given in the second and third split windows.
200 MIKE 11
Overview of the Boundary File
The content of the second split window depends on the combination of
Boundary Description and Boundary Type given in the highlighted row in the Boundary Table in the upper split window. The basic purpose of the second split window is to specify the necessary boundary conditions and in some cases select whether information should be specified for additional modules, e.g. AD boundaries, AD-RR links etc.
The content of the third split window will again depend on the specifications given in the second split window. The third split window deals primarily with boundaries for the AD and ST modules.
Boundary conditions can be specified as either a time series (TS Type) or constant values. If AD components are required the user can choose between additional data types as: Concentration, Bacteria Concentration,
Salinity, Temperature and Undefined.
If a constant boundary is specified under TS Type in the second split window, the user can select the type of data from a drop-down list in the Data
Type column. If a time series is specified, the corresponding Data Type field cannot be edited, but will be updated based on the data type of the actual time series selected.
When the Boundary Description is Closed or the Boundary Type is Sedi-
ment Supply no additional data is required.
The Inflow Boundary
Open Inflow Boundary
Open inflow boundaries are used to specify inflows at free branch ends
(boundaries of the model domain) for HD, AD and MIKE 12 simulations.
The layout for the Inflow boundary for Open Boundaries is shown in Figure 4.6. (Note the AD-RR option is not available for open boundaries).
The three check boxes available are: z
Include HD Calculation. This box must be checked if the discharge time series is to be included in the water balance in the HD calculation. z z
Include AD calculation. This box must be checked if the discharge is to be used with a concentration to compute the mass inflow of a component in an AD simulation. When checked, the associated concentrations are entered in the third split window.
Mike 12. If this check box is checked the boundary is applied to a two layered branch.
Boundary Editor
201
Boundary Editor
202
Figure 4.6
Specification of a discharge at an open inflow boundary.
Figure 4.6 shows the specification of a simple discharge boundary for a
HD model. The discharge (either constant or a time series) is specified in the second split window.
If the ‘Include AD calculation’ box is checked, additional information is needed in the second split window, see figure 4.7. This information deals with how the AD boundary should be processed during the simulation.
There are three possibilities:
TS-Defined means that the concentration at the boundary node will be equal to value in the specified time series.
Open, Concentration. This option is used at locations where outflow from the model area takes place. When an outflow boundary becomes an inflow boundary during a model simulation (eg due to tidal conditions) the boundary condition is adjusted according to:
C
=
C bf
+
(
C out
–
C bf
)e
–
t mix k mix
(4.1)
Where C bf
is the boundary concentration specified at the location, C out
is the computed concentration at the boundary immediately before the flow direction changed, K mix
is a time scale specified in the input and t time since the flow direction changed.
mix
is the
When outflow occurs the boundary conditions is defined as
∂
2
C
0
∂x
2
=
(4.2)
MIKE 11
Overview of the Boundary File
Open, Transport. This type of boundary should be used where only inflow takes place. The transport into the model area is computed using the specified boundary concentration and the discharge computed by the HD model. In this way the computed concentration in the boundary node can differ from the concentration specified in the boundary file. It may be used where appreciable storage and hence dilution of the inflow can take place close to the boundary.
Boundary Editor
Figure 4.7
Specification of a boundary for a combined HD and AD simulation.
If the ‘Mike 12’ box is checked the layout of the boundary file changes as shown in figure 4.8. It is now possible to define a discharge for both the upper and the lower layer. Further there are now four possible AD boundary types as each of the two layers can be a closed boundary. If the Bound-
ary Description were chosen as closed then both of the layers would be regarded as closed boundaries. By specifying an Open boundary in the
Boundary Description it is still possible to set one of the layers as closed e.g. the top layer can be of the Open, Transport type and the bottom layer
Closed. This combination is often used at upstream boundaries. In the lower window, each component concentration needs to be defined for both top and bottom layers.
203
Boundary Editor
Figure 4.8
Specification of an Open Inflow boundary for a combined HD, AD and MIKE 12 simulation. Boundaries need to be specified for both top and bottom layers.
If the ‘Include HD calculation’ box is now unchecked it is no longer necessary to enter information on the discharge, see figure 4.9. In this case a
HD simulation result file must already exist and is used as input to a subsequent AD simulation.
204
Figure 4.9
Specification of AD and MIKE 12 boundaries when using a previously computed HD result.
MIKE 11
Overview of the Boundary File
Point Source or Distributed Source Inflow Boundary
Point or distributed source inflow boundaries are used to describe lateral inflows for HD, AD and MIKE 12 simulations. Figure 4.10 shows the layout of the boundary file for the Inflow Boundary. The second split window is similar to that displayed for Open inflow boundaries, with one additional facility: z
AD-RR. If this check box is checked AD components can be included with the inflow generated by the rainfall runoff models integrated in
MIKE11.
In Figure 4.10 only the ‘Include HD calculation’ box is checked. It thus represents a standard lateral inflow used in a HD simulation. Only the discharge need be specified, as either a constant value or a time series.
Boundary Editor
Figure 4.10
Specification of a point source lateral inflow for a HD simulation.
If the ‘Include AD calculation’ box is also checked then the third split window becomes editable and boundaries for the different AD components can be entered, see Figure 4.11.The discharge specified in the second split window is used both in the water balance and in the AD calculation. In the AD calculation it is multiplied with the concentrations in order to calculate the mass inflow for the different components. Note that if only an AD simulation was to be computed (based on a previous
HD simulation), the “Include HD Boundaries” would be turned off. However the discharge would still need to be specified in order to compute the mass inflow of the components to the AD model.
If the Boundary Description was changed to Distributed Source and a second chainage were specified in the first split window this boundary would also be valid for a distributed inflow.
205
Boundary Editor
Figure 4.11
Specification of a point source boundary for both HD and AD simulations.
If the ‘Mike 12’ box is now also checked a new data section appears in the second split window, see figure 4.12. (Note that the ‘AD-RR’ check box is now hidden as this facility is not available in combinations with MIKE12 simulations.) In the second split window, a discharge time series must be specified together with the level at which the inflow occurs. The specification of the AD components is given in the bottom window.
206
Figure 4.12
Specification of a point source boundary for a combined HD, AD and MIKE12 simulation.
MIKE 11
Overview of the Boundary File
Figure 4.13 shows the layout of the boundary file if we now uncheck the
‘Include HD calculation’ box. It is actually the same layout as if the
‘Include HD calculation’ box is left checked. This is because information on the discharge is still required in order to calculate the mass flux of AD components into the river branch. The only difference is that the discharge is no longer used in the water balance.
Boundary Editor
Figure 4.13
Specification of a Point Source inflow boundary for a combined AD-
MIKE12 simulation. The discharge is not included in the water balance when the ‘Include HD calculation’ is left unchecked.
In figure 4.14 the ‘AD-RR’ box is checked. This facility can be used where the concentration of rainfall or runoff from a NAM model are to be used in an AD simulation. All other check boxes are now invisible.
Instead there is a section where information on the Catchment Name,
Catchment Area and Runoff Type must be specified. The Catchment
Name must refer to a catchment included in the MIKE11 set up. The area is used as a scaling factor meaning that runoff calculated by the rainfall runoff model is scaled pro rata against the catchment area specified in the rainfall-runoff editor. The runoff type must be selected between Total
Runoff, Surface Runoff, Root Zone Runoff, Groundwater Runoff or Rainfall. Note that Interflow is only available for the NAM model. The AD-RR facility is not available with MIKE12 branches. Also note that the Rainfall
Runoff model must run in parallel with the HD and AD models for the
AD-RR facility to operate.
207
Boundary Editor
Figure 4.14
Specification of rainfall or runoff for input to an AD simulation. The second split window now contains information on catchment name, catchment area and runoff type.
The Water Level Boundary
The Water level boundary is valid in connection with an Open boundary.
Note the “Include HD Calculation” box is not visible, as this is not an option -see figure 4.15.The boundary is specified as either a time series or a constant in the lower window.
208
Figure 4.15
Specification of a simple water level boundary for a HD simulation.
For a MIKE 12 simulation, the specification is very similar, except that water levels are defined for both top and bottom layers, see figure 4.16.
MIKE 11
Overview of the Boundary File
Figure 4.16
Specification of a water level boundaries for a MIKE 12 simulation.
Levels are required for both top and bottom layers.
Where an AD simulation is to be carried out in parallel to a HD simulation, the “Include AD Boundaries” box should be checked as shown in figure 4.17. The water level boundary is specified in the second split window together with information on the AD boundary type. An open, concentration boundary type is used because outflow occurs at the downstream end.
AD boundaries are specified in the third split window.
Boundary Editor
Figure 4.17
Specification of a water level boundary for a combined HD-AD simulation. Open concentration boundaries with a suitable k mix used as this is an outflow boundary.
value are
Finally, if both “Include AD Boundaries” and “MIKE 12” boxes are checked, the editor dialogue will be as shown in figure 4.18. The user
209
Boundary Editor needs to specify water levels and concentrations in both top and bottom layers.
Figure 4.18
A water level boundary with ‘Include AD calculation’ and ‘Mike 12’ check boxes checked. The water level must be specified at the second split window together with information on the AD boundary type.
Boundaries for the AD components are specified in the third split window.
The Q-h Boundary
Q-h (discharge-water level relation or rating curve) boundaries can be applied at Open boundaries only, and are usually applied at the downstream end of a model domain. If a Q-h relation is selected, the user will be presented with the display as shown in figure 4.19.
210
Figure 4.19
Specification of a Q-H relation at an Open boundary.
MIKE 11
Overview of the Boundary File
The Q-h relation is given in the table in the second split window. The Q-h relation can either be entered from a known rating curve (eg. copied and pasted from Excel) or automatically generated by selecting Tools in the top menu bar. If this later option is selected a new dialog appears, see figure 4.20.
Figure 4.20
Dialog used when making automatic calculation of Q-h relation.
The user must select the TOPO ID of the cross section to be used select whether the Q-h relation should be calculated assuming critical flow or uniform flow via the Manning equation. If the latter is chosen the bed slope and Manning’s “n” or “M” must be specified. Because information on the cross section is needed this facility is only available when the simulation editor is open and the paths to the cross section and boundary files have been specified.
AD boundaries may be specified together with the Q-h relation. If this is done (as shown in figure 4.21) the user must specify the type of AD boundary (typically Open, Concentration for a downstream boundary) and enter information on the boundaries in the lower window.
Boundary Editor
211
Boundary Editor
Figure 4.21
Specification of a Q-h boundary to be used in a combined AD-HD simulation.
Dam Break Boundary
Dam Break boundaries need to be specified when a dam break structure with a time-dependent breach formation in included in the river network file. The specification of the boundaries is quite simple as illustrated in
Figure 4.22. The second split window indicates that three time series must be specified: Dam Breach Level; Dam Breach Width; and Dam Breach
Slope.
212
Figure 4.22
Specification of a Dam Break boundary. Note the absence of the third split window, which is not necessary for this, and the other combinations of Boundary Description and Boundary Type shown.
MIKE 11
Overview of the Boundary File
Dam Boundary
Dam Boundaries are used in connection with stratified branches (MIKE
Reservoir model) when extraction from the dam needs to be specified. The discharge value or time series is given in the second split window, while the Level, Width and Height of the discharge point (extraction) should be given in the third split window, see figure 4.23.
Boundary Editor
Figure 4.23
Specification of a Dam Boundary for a stratified branch (MIKE Reservoir model). Discharge is specified in the second split window and the geometrical data of the extraction point is specified in the third split window.
Rainfall and Evaporation Boundary
Figure 4.24 shows the layout for a Rainfall boundary, which can either be applied globally or as a distributed source. When applying a rainfall boundary to a HD computation, the rainfall is converted to a lateral discharge by multiplying the rainfall depth with the actual flooded area associated with each computational water level point. The actual flooded area is in turn computed during the simulation from the current cross section storage width (and if applicable, additional flooded area) and the cross section spacing. If an evaporation time series is specified, the lateral
“inflow” will be negative, ie an outflow. Note that if a NAM result is used as input to a HD simulation, the incorporation of rainfall and evaporation is handled automatically without the need for a separate boundary file.
If the rainfall input is to be used as a source for an AD model, the “Include
AD boundaries” should be checked. In this case the concentration of components in the rainfall are specified in the third split window. Component numbers must match those in the AD parameter file. A boundary for component number ‘0’ will be applied to all components not otherwise specified.
213
Boundary Editor
214
Figure 4.24
The layout of the boundary file when the Boundary Type is chosen to be rainfall. The second split window now contains a check box used to specify if AD components should be included. AD components must be specified in the third split window.
Sediment Transport Boundary
Figures 4.25 and 4.26 show the layout of the boundary file for Sediment
Transport, which can be specified for either an open boundary or a point source. The second split window holds information on the time series needed and also requires information about the type of sediment transport included in the computations: single or multiple (graded) sediment fractions. In figure 4.25, data for only one sediment fraction is needed and the relevant time series is assigned in the second split window.
MIKE 11
Overview of the Boundary File
Figure 4.25
Specification of a sediment inflow boundary for a single sediment fraction (total transport)
Figure 4.26 shows the layout of the boundary file for a graded sediment model boundary. The third split window now prompts the user for fraction numbers. The fraction numbers refer to the different fractions defined in the Sediment Transport Editor.
Sediment inflow boundaries (either total or graded sediment) can also be specified as point source inflows.
Boundary Editor
Figure 4.26
Specification of a sediment inflow boundary for graded sediment transport.
The Bottom level Boundary
Bottom level (river bed level) boundaries can be specified in conjunction with the sediment transport model, at Open boundaries only. Figure 4.27 shows the layout for a Bottom Level Boundary. In the second split win-
215
Boundary Editor dow the user specifies whether the boundary data are the absolute bottom level or the change in bottom level. The time series for both types are specified in the second split window. If the data is selected as change in bottom level the absolute bottom level is calculated during the simulation based its initial value.
If the Bottom Level Boundary Type is used in combination with a graded sediment model it is necessary to specify the relative amount of the different sediment fractions. This is done in the third split window. As indicated in figure 4.10 it is possible to select between Fraction Value or Change in
Fraction Value. This is done in the ‘Type, Fraction data’ column. If the
“Change in Fraction Value” is set to zero, the initial distribution of the sediment fractions will apply throughout the entire simulation.
Figure 4.27
Specification of a Bottom Level boundary for ST simulations. The user selects whether the data are interpreted as absolute bottom level or change in bottom level. If the graded sediment model is used, data for the individual fractions are to be specified in the third split window.
4.3
Tools
The new boundary editor includes a number of tools to assist the user in setting up complex model boundaries and quickly modifying the time series inputs.
4.3.1
Quick set up of Graded Sediment Boundaries
A quick method to set up boundaries for graded sediment models is to use the tool ‘Make List of Fractions’. This tool is found under “Tools” in the
216 MIKE 11
Tools top menu bar and is available when the lower split window is active. If the
Boundary Type is chosen as Sediment Transport a dialog will appear, see figure 4.28. This dialog can be used to specify several boundaries simultaneously. The boundaries can be either constant values or time series, depending on the selection made in the TS Type edit field.
If constant boundaries are chosen the number of fractions should be entered together with the value of the constant boundary in the ‘Nb. Of
Fractions’ and ‘File/Value’ edit fields, respectively. If time varying boundaries are requested a time series file should be selected. When the OK button is pressed all legal time series items (time series with the requested data type) in the time series file will be inserted as boundaries in the third split window. The first legal time series will be applied for fraction number 1, the second for fraction number 2 etc.
Figure 4.28
Dialog for quick specification of graded sediment inflow boundaries
If the “Make List of Fractions” Tool is used for Boundary Types equal to
Bottom Level the dialog is slightly changed, see figure 4.29. Now the user must specify if the boundaries should be ‘Fraction Value’ or ‘Change in
Fraction Value’.
Figure 4.29
Dialog for quick specification of graded sediment bottom levelboundaries
4.3.2
Quick set up of AD Boundaries
AD boundaries can be specified in a similar way to that described for graded sediments above. Make sure the lower split window is active, then
Boundary Editor
217
Boundary Editor select from the top menu bar ‘Make List of Components’. The dialog that appears is shown in figure 4.30. This dialog works in a similar manner to the dialog used to set up graded sediment boundaries. If constant boundary values are requested the user must select the Data Type and enter the number of components and the boundary value. If time varying boundaries are requested the user must select the appropriate file. All legal (ie concentration) time series items in the time series file will then be used as boundaries. The first legal time series is used for component number one the second legal time series for component number 2 etc.
Figure 4.30
Dialog for quick specification of AD boundaries
If the boundary is open and used for a MIKE 12 simulation the tool operates slightly differently. If time varying boundaries are requested then the two first legal time series are used for component number 1: The first is used for the top layer and the second for the bottom layer. If constant boundaries are requested the user will have to specify whether the values are for the top or the bottom layer, see figure 4.31.
Figure 4.31
Dialog for quick specification of MIKE 12 boundaries. The user must define if it is valid for the top layer or the bottom layer.
4.3.3
Copying Point Source Boundaries
In order to assist the user in the creation of a boundary file containing many point sources, a tool “Copy/Paste Boundary Condition” has been implemented under “Tools” in the top menu bar. Note that the boundary to be copied must be highlighted. This facility works only for Point Sources when both the Mike 12 and the AD-RR boxes are unchecked.
218 MIKE 11
Tools
When this option is selected a dialog appears, see figure 4.32. This dialog reflects a HD point source with a location (branch name and chainage), a boundary ID and a discharge boundary. In this dialog each row represents a new boundary. The user specifies the branch name and chainage for the new boundary in the first two columns, and optionally the boundary ID.
The last two columns (with the common header Discharge) are used to specify the discharge. If they are left empty the same discharge boundary will be used for the new boundaries. If the new boundaries should use other discharges the necessary information is entered here. If constant values are requested only the File /Value edit field should be filled out. The dialog can also be filled by copying data from an Excel spreadsheet. When the dialog is closed the user is asked if the new boundaries should be pasted into the boundary editor.
Figure 4.32
Dialog for copying a HD point source
If the point source being copied also includes AD boundaries the dialog will also offer a possibility to change these boundaries, see figure 4.33, in which a point source for three AD components are being copied. The columns for the components work in the same way as the columns used to copy the discharge.
Figure 4.33
Dialog for copying a AD Point source.
4.3.4
Scale factor
In certain situations it can be useful to scale one or more of the boundaries without changing the time series. This may be the case if a discharge hydrograph representing catchment runoff needs to be applied to a number
Boundary Editor
219
Boundary Editor of smaller sub-catchments. Alternatively boundaries may be scaled up or down as part of a sensitivity analysis.
The Scale Factor field is hidden by default but can be made visible by right clicking the mouse in the File/Value edit field and then selecting
Scale factor from the pop up menu. The specified Scale Factor will be multiplied with the boundary conditions value (constant or time series).
Figure 4.29 shows an AD point source with three components in which the second component is reduced by 20 percent.
220
Figure 4.34
AD point source where the second component is reduce with 20 percent.
An additional tool is available to quickly change scale factors. The
“Change Scale Factors” tool is found under Tools in the top menu bar when the first split window is active. Note that this tool works for point sources of the inflow type only. The dialog is shown in figure 4.30.
The user specifies the branch name and chainage interval to which the change in scale factor(s) applies. Leaving the branch name blank corresponds to selecting all branches, but the chainage interval must still be specified. A new scale factor for the discharge boundary can be entered in the appropriate field. If this is left blank no changes will take place.
For AD boundaries, the scale factor of individual components can be changed. If the component number is left blank the new scale factor will be applied to all components. The new scale factor for the AD components must be entered; if left blank the scale factor will not be changed.
MIKE 11
Tools
Figure 4.35
Change Scale factor dialog
Boundary Editor
221
Boundary Editor
222 MIKE 11
R A I N F A L L - R U N O F F E D I T O R
223
224 MIKE 11
5 RAINFALL-RUNOFF EDITOR
The Rainfall Runoff Editor (RR-editor) provides the following facilities: z z z z
Input and editing of rainfall-runoff and computational parameters
required for rainfall-runoff modelling.
Specification of timeseries. T
ime series are specified on the Timeseries page within the Rainfall Runoff Editor. In other MIKE 11 modules, the time series input are specified in the boundary file.
Calculation of weighted rainfall
through a weighting of different rainfall stations to obtain catchment rainfall.
Digitising of catchment boundaries and rainfall stations in a graphical
display (Basin View) including automatic calculation of catchment areas and mean area rainfall weights.
z
Presentation of Results. Specification of discharge stations used for
calibration and presentation of results.
Some of the features in the Rainfall Runoff package have been developed in cooperation with CTI Engineering, CO., Ltd., Japan. Amongst these are additional methods for Calculation of Runoff from catchments and Calculation of Mean Precipitation of basins (method of Thiessen polygons and
Isohyetal Mapping).
Simulation
The Rainfall Runoff Editor builds a file containing all the specified data with extension .RR11. Once the catchments have been defined and the rainfall-runoff, and the model parameters specified in the rainfall-runoff editor, the Simulation is started from the MIKE 11 Run (or simulation)
Editor. It should be noticed that: z z
Time step: It is recommended to use a time step not larger than the time step in the rainfall series and not larger than the time constant for rout-
ing of overland flow. See example on Figure 5.2.
Simulated catchment results can be linked with the River Network.
Catchment runoff/discharges and be inputted as lateral inflows and
summed to Normal and Routing river branch types, see sections 2.5.2
and 2.4 in the River Network Editor guide.
Results
MIKE 11 generates a variety of output types from a Rainfall Runoff simulation ready to be used for model calibration and result presentation. These
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Figure 5.1
Input page to the rainfall-runoff simulation in the Simulation Editor
226
Figure 5.2
Simulation page to the rainfall-runoff simulation in the Simulation
Editor. In this example aTimestep=12 hours.
Editing using the clipboard
Overviews in the Editor shown in the bottom of each page can be copied to the clipboard. This facility is useful, when editing a setup with many catchments. Editing of the rainfall-runoff parameters can be carried out in a spreadsheet after having copied the Overview to the spreadsheet via the clipboard. After editing, the parameters are copied back to the Overview and saved in the Rainfall Runoff Editor.
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Specifying model Catchments
5.1
Specifying model Catchments
The catchment page is used to prepare the catchments to be included in the
Figure 5.3
The Catchment page. Additional catchments are prepared via the
Insert Catchment dialog. The Example includes 2 sub-catchments and a combined catchment which includes the 2 sub-catchments
Inserting Catchments
New catchments are defined via the Insert Catchment dialog (see
Figure 5.4). The insert catchment dialog is automatically activated for the
first catchment, when creating a new RR-parameter. A new RR parameter
File is created from the MIKEZero File dialog. Additional catchments are defined when pressing the button: Insert catchment.
A new catchment can be prepared as a copy with parameters from an
existing catchment or with default parameters (see Figure 5.4). The copy
also includes time series from the existing catchment.
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Figure 5.4
Insert Catchment Dialog.
Catchments Definitions
A catchment is defined by:
Catchment Name
Simulations can be carried out for several catchments at the same time.
The catchment name could reflect e.g. the location of the outflow point.
Rainfall Runoff Model type
The parameters required for each Rainfall-Runoff model type are speci-
fied in separate pages in the editor (see Figure 5.3). Following models can
be selected:
1 NAM: A lumped, conceptual rainfall-runoff model, simulating the overland-, inter- flow, and base-flow components of catchment runoffs as a function of the moisture contents in four storages. NAM includes a number of optional extensions, including an advanced snow-melt routine and a separate description of the hydrology within irrigated areas.
Auto calibration is available for 9 important parameters.
2 UHM: The Unit Hydrograph Module includes different loss models
(constant, proportional) and the SCS method for estimating storm runoff.
3 SMAP: A monthly soil moisture accounting model.
4 Urban: Two different model runoff computation concepts are available in the Rainfall Runoff Module for fast urban runoff.: A) Time/area
Method and B) Non-linear Reservoir (kinematic wave) Method
5 Combined: The runoff from a number of catchments, constituting parts of a larger catchment, can be combined into a single runoff series.
Each of the sub- catchments must be specified separately by name, model type, parameters etc. The combined catchment can be defined only after the sub-catchments have been created. The combined catch-
MIKE 11
The NAM Rainfall-runoff model ment is defined in the group for combined catchments, which is activated when selecting combined catchment. The runoff from the combined catchment is found by simple addition of the simulated flow from the sub-catchments.
Catchment Area
Defined as the upstream area at the outflow point from a catchment.
Calibration plot
A calibration plot will automatically be prepared for catchments, where the time series for observed discharge have been specified on the Time series Page and the selection of calibration plot has been ticked off. The calibration can be loaded from the Plot composed and is saved in the subdirectory RRCalibration with the file name: Catchment-name.plc. The time series in these plots are also available in DFS0 format in the subdirectory RRcalibration with the file name: Catchmentname.dfs0.
Figure 5.32 shows an example on a calibration plot.
Calculated Areas
The Calculated area shown in the Catchment Overview is based on the digitised catchment boundaries in the Graphical display. The calculated
area is activated when the Basin View has been selected, see section 5.10.
The Catchment Area is shown in the edit fields for Area and Calculated
Area, when transferring a catchment from the Basin View to the catchment page. The Area which is used in the model calculation can afterwards be modified manually.
Example on a catchment setup
The catchment data included in Figure 5.3 is input data to a setup of a
catchment in Poland. Rainfall Runoff parameters from this setup is used in many of the following illustrations. The setup of the catchment is further
described in Section 5.12: A step-by-step procedure for using for using the
Rainfall Runoff Editor.
5.2
The NAM Rainfall-runoff model
The NAM model is a deterministic, lumped and conceptual Rainfall-runoff model accounting for the water content in up to 4 different storages.
NAM can be prepared in a number of different modes depending on the requirement. As default, NAM is prepared with 9 parameters representing the Surface zone, Root zone and the Ground water storages. In addition
NAM contains provision for:
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– Extended description of the ground water component.
– Two different degree day approaches for snow melt.
– Irrigation schemes.
– Automatic calibration of the 9 most important (default) NAM parameters.
Parameters for all options are described below.
5.2.1
Surface-rootzone
Parameters used in the surface and the root zone are described below (see
230
Figure 5.5
NAM - Surface Rootzone.
Maximum water content in surface storage (Umax).
Represents the cumulative total water content of the interception storage
(on vegetation), surface depression storage and storage in the uppermost layers (a few cm) of the soil. Typically values are between 10 - 20 mm.
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The NAM Rainfall-runoff model
Maximum water content in root zone storage (Lmax)
Represents the maximum soil moisture content in the root zone, which is available for transpiration by vegetation. Typically values are between 50
– 300 mm.
Overland flow runoff coefficient (CQOF)
Determines the division of excess rainfall between overland flow and infiltration. Values range between 0.0 and 1.0
Time constant for interflow (CKIF)
Determines the amount of interflow, which decreases with larger time constants. Values in the range of 500-1000 hours are common.
Time constants for routing overland flow (CK1, 2)
Determines the shape of hydrograph peaks. The routing takes place through two linear reservoirs (serial connected).
Without tickmark on CK2 the model will use the same time constant for the two linear reservoirs (CK1=CK2).
The routing will take place through one linear reservoir with CK2=0.
Otherwise the routing takes plase through two linear reservoirs (CK1 for the first reservoir and CK2 for the second reservoir).
High, sharp peaks are simulated with small time constants, whereas low peaks, at a later time, are simulated with large values of these parameters.
Values in the range of 3 - 48 hours are common.
Root zone threshold value for overland flow (TOF)
Determines the relative value of the moisture content in the root zone
(L/Lmax) above which overland flow is generated. The main impact of
TOF is seen at the beginning of a wet season, where an increase of the parameter value will delay the start of runoff as overland flow. Threshold value range between 0 and 70% of Lmax, and the maximum values allowed is 0.99.
Root zone threshold value for inter flow (TIF)
Determines the relative value of the moisture content in the root zone
(L/Lmax) above which interflow is generated.
5.2.2
Ground Water
For most NAM applications only the Time constant for routing baseflow
CKBF and possibly the Rootzone threshold value for ground water
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The Ground Water parameters are described below (see Figure 5.6).
Overall Parameters
Time constant for routing baseflow (CKBF)
Can be determined from the hydrograph recession in dry periods. In rare cases, the shape of the measured recession changes to a slower recession after some time. To simulate this, a second groundwater reservoir may be included, see the extended components below.
Root zone threshold value for ground water recharge (Tg)
Determines the relative value of the moisture content in the root zone
(L/Lmax) above which ground water recharge is generated. The main impact of increasing TG is less recharge to the ground water storage.
Threshold value range between 0 and 70% of Lmax and the maximum value allowed is 0.99.
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The NAM Rainfall-runoff model
Figure 5.6
NAM - Ground Water.
Extended Ground Water Component
Ratio of ground water catchment to topographical (surface water) catchment area (Carea)
Describes the ratio of the ground water catchment area to the topographical catchment area (specified under Catchments). Local geological condition may cause part of the infiltrating water to drain to another catchment.
This loss of water is described by a Carea less than one. Usual value: 1.0.
Specific yield for the ground water storage (Sy)
Should be kept at the default value except for the special cases, where the ground water level is used for NAM calibration. This may be required in riparian areas, for example, where the outflow of ground water strongly influences the seasonal variation of the levels in the surrounding rivers.
Simulation of ground water level variation requires a values of the specific yield Sy and of the ground water outflow level GWLBF0, which may vary in time. The value of Sy depends on the soil type and may often be
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Rainfall-Runoff Editor assessed from hydro-geological data, e.g. test pumping. Typically values of 0.01-0.10 for clay and 0.10-0.30 for sand are used.
Maximum ground water depth causing baseflow (GWLBF0)
Represents the distance in metres between the average catchment surface level and the minimum water level in the river. This parameter should be kept at the default value except for the special cases, where the ground water level is used for NAM calibration, cf. Sy above.
Seasonal variation of maximum depth
In low-lying catchments the annual variation of the maximum ground water depth may be of importance. This variation relative to the difference between the maximum and minimum ground water depth can be entered by clicking Edit Seasonal...
Depth for unit capillary flux (GWLBF1)
Defined as the depth of the ground water table generating an upward capillary flux of 1 mm/day when the upper soil layers are dry corresponding to wilting point. The effect of capillary flux is negligible for most NAM applications. Keep the default value of 0.0 to disregard capillary flux.
Abstraction
Ground water abstraction or pumping may be specified in a time series input file, in millimetres, or given as monthly values in mm by clicking
Edit Abstraction.
Lower base flow. Recharge to lower reservoir (Cqlow)
The ground water recession is sometimes best described using two linear reservoirs, with the lower usually having a larger time constant. In such cases, the recharge to the lower ground water reservoir is specified here as a percentage of the total recharge.
Time constant for routing lower baseflow (Cklow)
Is specified for CQlow > 0 as a baseflow time constant, which is usually larger than the CKBF
5.2.3
Snow Melt
The snow module simulates the accumulation and melting of snow in a
NAM catchment. Two degree-day approaches can be applied: a simple lumped calculation or a more advanced distributed approach, allowing the user to specify a number of elevation zones within a catchment with separate snow melt parameters, temperature and precipitation input for each zone.
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The NAM Rainfall-runoff model
The simple degree-day approach uses only the two overall parameters: a
constant degree-day coefficient and a base temperature.
The Snow melt module uses a temperature input time series, usually mean daily temperature, which is specified on the Timeseries page.
The Snow Melt parameters are described below (see Figure 5.7).
Figure 5.7
NAM - Snow Melt.
Include Snow melt
Ticked for a sub-catchments with snow melt included.
Overall Parameters
Constant Degree-day coefficient (Csnow).
The content of the snow storage melts at a rate defined by the degree-day coefficient multiplied with the temperature deficit above the Base Temperature. Typical values for Csnow is 2-4 mm/day/C.
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Base Temperature snow/rain (T0).
The precipitation is retained in the snow storage only if the temperature is below the Base Temperature, whereas it is by-passed to the surface storage
(U) in situations with higher temperatures. The Base Temperature is usually at or near zero degree C.
Extended Snow Melt Component
Seasonal variation of Csnow
May be introduced when the degree-day factor is assumed to vary over the year. Variation of Csnow may be specified in a time series input file or given as monthly values in mm/day/C by clicking Edit Seasonal.
Radiation coefficient
May be introduced when time series data for incoming radiation is available. The timeseries input file is specified separately on the time series page. The total snow melt is calculated as a contribution from the traditional snow melt approach based on Csnow (representing the convective term) plus a term based on the radiation.
Rainfall degree-day coefficient
May be introduced when the melting effect from the advective heat transferred to the snow pack by rainfall is significant. This effect is represented in the snow module as a linear function of the precipitation multiplied by the rainfall degree coefficient and the temperature deviation above the
Base Temperature.
Elevation Zones
Elevations zones are prepared in the elevation zone dialog (see Figure 5.8)
Number of elevation zones
Defines the number of altitude zones, which subdivide the NAM catchment. In each altitude zone the temperature and precipitation is calculated separately.
Reference level for temperature station
Defines the altitude at the reference temperate station. This station is used as a reference for calculating the temperature and precipitation within each elevation zone. (The file with temperate data is specified on the timeseries page).
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The NAM Rainfall-runoff model
Dry temperature lapse rate
Specifies the lapse rate for adjustment of temperature under dry conditions. The temperature in the actual elevation zone is calculated based on a linear transformation of the temperature at the reference station to the actual zone defined as the dry temperature lapse rate (C/100m) multiplied by the difference in elevations between the reference station and the actual zone.
Wet temperature lapse rate
Specifies the lapse rate for adjustment of temperature under wet conditions defined as days with precipitation higher than 10 millimetres. The temperature in the actual elevation zone is calculated based on a linear transformation of the temperature at the reference station to the actual zone defined as the wet temperature lapse rate (C/100m) multiplied by the difference in elevations between the reference station and the actual zone.
Reference level for precipitation station
Defines the altitude at the reference precipitation station (The file with precipitation data is specified on the timeseries page).
Correction of precipitation
Specifies the lapse rate for adjustment of precipitation. Precipitation in the actual elevation zone is calculated based on a linear transformation of the precipitation at the reference station to the actual zone defined as precipitation lapse rate (C/100m) multiplied by the difference in elevation between the reference station and the actual zone.
Elevation of each zone is specified in the table as the average elevation of
the zone. The elevation must increase from zone (i) to zone (i+1).
Area of each zone is specified in the table. The total area of the elevation
zones must equal the area of the catchment.
Min storage for full coverage
Defines the required amount of snow to ensure that the zone area is fully covered with snow. When the water equivalent of the snow pack falls under this value, the area coverage (and the snow melt) will be reduced linearly with the snow storage in the zone.
Maximum storage in the zone
Defines the upper limit for snow storage in a zone. Snow above this values will be automatically redistributed to the neighbouring lower zone.
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Max water retained in snow
Defines the maximum water content in the snow pack of the zone. Generated snow melt is retained in the snow storage as liquid water until the total amount of liquid water exceeds this water retention capacity. When the air temperature is below the base temperature T0, the liquid water of the snow re-freezes with rate Csnow.
Dry temperature correction, wet temperature correction and correction of precipitation in the zone can be specified manually or calculated automatically as defined above.
Figure 5.8
NAM - Snow Melt, Elevation Zones.
5.2.4
Irrigation
Minor irrigation schemes within a catchment will normally have negligible influence on the catchment hydrology, unless transfer of water over the catchment boundary is involved. Large schemes, however, may significantly affect the runoff and ground water recharge through local increases in evaporation and infiltration. If the effect of an irrigation area within a catchment is to be simulated, separate NAM catchments are defined for the irrigated area and the remaining area and a combined catchment defined to accumulate the runoff.
A time series of applied irrigation must be specified as a rainfall series on the timeseries page.
The Irrigation parameters are described below (see Figure 5.9).
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The NAM Rainfall-runoff model
Figure 5.9
NAM - Irrigation.
Include irrigation
Ticked for a sub-catchments with irrigation included.
Infiltration Parameters
Infiltration rate at field capacity (k0-inf)
Defines the infiltration, which is taken directly from the upper storage using a Horton-type description. This substitutes the standard NAM infiltration calculation, and the overland flow coefficient CQOF and the threshold value TOF are consequently not required, when irrigation is included.
Irrigation sources
Can be local ground water, a local river, an external river, or a combination of these. Local ground water will be taken from the NAM ground water storage and irrigation water taken from a local river will be subtracted from the simulated runoff. If all the water is abstracted from an external source, outside the catchment, no subtractions are made.
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Crop coefficients and operational losses
May be specified separately. The monthly crop coefficients are applied to the potential evaporation. The operational losses, including also conveyance losses, are given in percentage of the irrigation water as losses to
groundwater, overland flow or evaporation, (see Figure 5.10).
Figure 5.10
Seasonal variation of crop coefficients and losses.
5.2.5
Initial conditions
The initial conditions are described below.
Surface and Rootzone
The initial relative water contents of surface and root zone storage must be specified as well as the initial values of overland flow and interflow.
Ground water
Initial values for baseflow must always be specified. When lower baseflow are included a value for the initial lower baseflow must also be specified.
Snow melt
Initials values of the snow storage are specified when the snow melt routine is used. When the catchment are delineated into elevation zones, the snow storage and the water content in each elevation zones are specified.
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The NAM Rainfall-runoff model
Figure 5.11
NAM - Initial Conditions.
5.2.6
Autocalibration
Automatic calibration is possible for the most important parameters in the
NAM model. A detailed description of the automatic calibration is given in the Rainfall-runoff reference manual.
The parameters used in the autocalibration are described below (see
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Figure 5.12
NAM - Autocalibration.
Include Autocalibration
Ticked for a sub-catchment with autocalibration included.
Calibration parameters
The automatic calibration routine includes 9-12 model parameters: The actual number of parameters availabe for auto-calibration depends on choices for: 1) Separate value for CK2 and 2) Recharge to a lower reservoir.
– Maximum water content in surface storage (Umax).
– Maximum water content in root zone storage (Lmax)
– Overland flow runoff coefficient (CQOF)
– Time constant for interflow (CKIF)
– Time constants for routing overland flow (CK1, 2)
– Root zone threshold value for overland flow (TOF)
– Root zone threshold value for inter flow (TIF)
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The NAM Rainfall-runoff model
– Time constant for routing baseflow (CKBF)
– Root zone threshold value for ground water recharge (Tg)
– Time constants for routing overland flow (CK2)
– Recharge to lower baseflow (CQLOW)
– Time constants for routing lower baseflow(CKLOW)
The user specifies which of these parameters should be included in the autocalibration and the minimum and maximum range for each parameter.
Objective Function
In automatic calibration, the calibration objectives have to be formulated as numerical goodness-of fit measures that are optimised automatically.
For the four calibration objectives defined above the following numerical performance measures are used:
1 Agreement between the average simulated and observed catchment runoff: overall volume error.
2 Overall agreement of the shape of the hydrograph: overall root mean square error (RMSE).
3 Agreement of peak flows: average RMSE of peak flow events.
4 Agreement of low flows: average RMSE of low flow events.
The user determined which of these objectives should be considered in the autocalibration.
Stopping Criteria
The automatic calibration will stop either when the optimisation algorithm ceases to give an improvement in the calibration objective or when the maximum number of model evaluation is reached.
Exclude Initial period
The automatic calibration routine can exclude an initial number of days in the warm up period specified as initial number of days excluded.
Running the autocalibration
After preparing the autocalibration parameters the autocalibration is started as a normal simulation.
When the autocalibration is completed the message box as shown in
Figure 5.13 will pop up. The Revised parameters are made available by
reloading the RR-file.
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A calibration plot of the results is prepared in the RRcalibration directory and can be loaded via the Plot-composer.
Figure 5.13
Message box after autocalibration is finished.
5.3
UHM
Introduction
The UHM (Unit Hydrograph) module constitutes an alternative to the
NAM model for flood simulation in areas, where no streamflow records are available or where unit hydrograph techniques are already well established.
The module includes a number of simple unit hydrograph models to estimate the runoff from single storm events. The models divide the storm rainfall in excess rainfall (or runoff) and water loss (or infiltration).
The UHM parameters are described below (see Figure 5.14).
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UHM
Figure 5.14
UHM Parameters
Areal adjustment and Baseflow
An areal adjustment factor (different from 1.0) may be applied if the catchment rainfall intensity is assumed to differ from the input rainfall data series.
A constant baseflow may be added to the runoff.
These parameters are used for all types of UHM models
Hydrograph
The distribution of the runoff in time can be described using different methods:
SCS triangular hydrograph
The standard hydrograph in which the time to peak is assumed to be half the duration of the excess rainfall plus the lag time t l
.
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SCS dimensionless hydrograph
Derived from a large number of natural unit hydrographs from catchments of varying size and location. The flow values are expressed in Q/Qp, where Qp is the peak discharge, and the time in T/Tp, where Tp is the time from the start of the hydrograph rise to the peak.
User defined hydrographs
Should be specified in their dimensionless form, i.e. Q/Qp as a function of
T/Tp, as for the SCS dimensionless hydrograph above.
Six other methods for describing the hydrograph are available. These are:
– Storage Function
– Quasi Linear Storage Function
– Nakayasu
– Rational method
– Kinematic Wave (rectangular basin)
– Kinematic Wave (Non-uniform slope length)
For each of these a number of parameters are to be given. These parameters are described in more details in the reference manual.
Loss model
Constant loss
The infiltration is described as an initial loss at the beginning of the storm followed by a constant infiltration:
Proportional loss
A runoff coefficient is specified as the ratio of runoff to the rainfall.
The SCS method
The SCS Loss model uses a Curve number that characterises the catchment in terms of soil type and land use characteristics.The model further operates with three different levels of the antecedent moisture conditions
AMC, where the initial AMC is specified.
Three other loss models are available. Theses are:
– Nakayasu
– f1-Rsa
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SMAP
– No loss
Lag time
Can be specified directly in hours or calculated by the standard SCS formula:
SCS formular
Three parameters are specified: Hydraulic Length, Slope and Curve
Number. Use the ‘calculate’ button to calculate the actual lag time.
5.4
SMAP
Introduction
SMAP is simple rainfall runoff model of the lumped conceptual type.
It has been designed to work on the basis of monthly input data and therefore constitutes an economic alternative to the NAM model in scenarios where a daily resolution of the results is not required. This is often the case in overall water resources planning or for analyses of longterm reservoir operations. In such situations data preparation time may be saved if simulations are carried out with monthly time steps only.
The SMAP model has been tested by DHI on various dry tropical and subtropical catchments and has shown almost the same degree of accuracy on the simulated monthly flow as the NAM model. The model does not include a snow melt routine and is not recommended to be used in areas where snow melt has significant influence on the hydrographs.
Model Parameters
The model accounts for the water storage in two linear reservoirs representing the root zone and the groundwater reservoirs respectively.
SMAP has five calibration parameters (see Figure 5.15):
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Figure 5.15
SMAP Parameters
Max Storage Content of Root Zone (SAT)
Determines the maximum storage in the root zone storage at saturation in millimetres. The parameter determines how much water is available for evapotranspiration. The model does not account for evaporation from interception or surface depressions. Thus the magnitude of SAT is normally somewhat larger than what may be estimated from rooting depth and field capacity. Values of SAT range from 300 mm to 1500 mm. The parameter influences the total evaporation in the model and hence the overall water balance.
Similar to the NAM model many of the process descriptions in the SMAP model depends on the current saturation fraction of the root zone storage.
I.e. the current storage of water (RSOL) divided by the max. possible storage (MAX).
Surface Runoff exponent (E2)
SMAP calculates the Surface runoff (OF) as a fraction of the rainfall input during the Time step (P). The surface runoff depends both of the degree of
MIKE 11
SMAP saturation of the root zone and of the exponent E2. Note that the surface runoff will be the full rainfall amount when the root zone is saturated.
Small values of E2 will increase the runoff. It is recommended to start calibration with E2 values close to 1.
Evaporation Exponent
The actual evaporation (EA) is calculated as a fraction of the potential
Evapotranspiration (EP). It depends on the current saturation degree of the root zone and the exponent E1. Small E1 will increase the Evaporation.
Groundwater Recharge Coefficient (Crec)
Crec determines, together with the degree of saturation in the root zone, the amount of the current root zone water content (REC) to be transferred to the groundwater in each time step. Crec varies between 0 and 1.
The parameter influences the total amount of base flow generated by the model.
Base flow Routing constant (CK)
The base flow routing constant (CK) is the time constant of the linear groundwater reservoir and is entered in the selected time unit (e.g. hours).
The larger the value the slower the base flow routing. Normal interval is between 500 hours and 3000 hours.
Autocalibration Option
Not yet implemented!
In addition to the above parameters the root zone content (in mm) at the start of the simulation and the initial base flow (in m3/s) needs to be specified.
Calculation Time Step
The calculations in SMAP are non-iterative and fully forward centred.
Hence, all calculations are based on the stage variables calculated in the previous time step. It is therefore recommended to perform calculations using daily calculation time steps even in situations where the rainfall input is on a monthly basis. The output (or storing) frequency can be selected on the Results page in the simulation editor and may be set to 30 days if comparison with monthly data are required. This ensures current update of the stage variables within an output interval and improves the results.
Please note, however, that the discharge output in the main result file is in m3/s and represent an instantaneous value at by the end of the last calcula-
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Values of specific discharge (in mm) accumulated over the storing interval are available in the file for additional results. This file also includes time series of other relevant parameters such as groundwater recharge, base flow and root zone moisture.
5.5
Urban
5.5.1
Introduction
Two different urban runoff computation concepts are available in the
Rainfall Runoff Module as two different runoff models:
Model A) Time/area Method
Model B) Non-linear Reservoir (kinematic wave) Method
The Model type (A/B) is selected in the first group box Model Parameters
-> Model (see Figure 5.16 and Figure 5.17)
5.5.2
Urban, model A, Time/area Method
The concept of Urban Runoff Model A is founded on the so-called "Time-
Area" method. The runoff amount is controlled by the initial loss, size of the contributing area and by a continuous hydrological loss.
The shape of the runoff hydrograph is controlled by the concentration time and by the time-area (T-A) curve. These two parameters represent a conceptual description of the catchment reaction speed and the catchment shape.
The Parameters for Model A are described below (see Figure 5.16)
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Figure 5.16
Urban Page. Model A,
Time/area Method.
Impervious Area
The Impervious area represents the reduced catchment area, which contributes to the surface runoff
Time of Concentration
Defines the time, required for the flow of water from the most distant part of the catchment to the point of outflow
Initial Loss
Defines the precipitation depth, required to start the surface runoff. This is a one-off loss, comprising the wetting and filling of catchment depressions.
Reduction factor
Runoff reduction factor, accounts for water losses caused by e.g. evapotranspiration, imperfect imperviousness, etc. on the contributing area.
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Time/Area Curve
Accounts for the shape of the catchment lay-out, determines the choice of the available T/A curve to be used in the computations.
Three pre-defined types of the T/A curves are available:
1) rectangular catchment
2) divergent catchment
3) convergent catchment
5.5.3
Urban, model B, Time/area Method
The concept of surface runoff computation of Urban Runoff Model B is founded on the kinematic wave computation. This means that the surface runoff is computed as flow in an open channel, taking the gravitational and friction forces only. The runoff amount is controlled by the various hydrological losses and the size of the actually contributing area.
The shape of the runoff hydrograph is controlled by the catchment parameters length, slope and roughness of the catchment surface. These parameters form a base for the kinematic wave computation (Manning equation).
The Parameters for Model B are described below (see Figure 5.17)
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Figure 5.17
Urban Page. Model B,
Non-linear Reservoir (kinematic wave)
Method
Length
Conceptually, definition of the catchment shape, as the flow channel. The model assumes a prismatic flow channel with rectangular cross section.
The channel bottom width is computed from catchment area and length.
Slope
Average slope of the catchment surface, used for the runoff computation according to Manning.
Area
The area distribution percentages divide the catchment area into five subcatchments with identical geometrical, but distinct hydrological properties. The five sub catchment types are:
– impervious steep
– impervious flat
253
Rainfall-Runoff Editor
– pervious -small impermeability
– pervious - medium impermeability
– pervious - large impermeability
The hydrological properties of each of the sub-areas can be adjusted by
modifying the appropriate hydrological parameters (see Figure 5.18 show-
ing default values). The sum of the specified areas (in %) must be equal to
100%.
254
Figure 5.18
Model B, Hydrological Parameters for individual sub-catchments.
Wetting loss
One-off loss, accounts for wetting of the catchment surface.
Storage loss
One-off loss, defines the precipitation depth required for filling the depressions on the catchment surface prior to occurrence of runoff.
Start infiltration
Defines the maximum rate of infiltration (Horton) for the specific surface type.
End infiltration
Defines the minimum rate of infiltration (Horton) for the specific surface type
.
MIKE 11
Urban
Horton's Exponent
Time factor "characteristic soil parameter". Determines the dynamics of
the infiltration capacity rate reduction over time during rainfall. The actual infiltration capacity is made dependent of time since the rainfall start only.
Inverse Horton´s Equation
Time factor used in the "inverse Horton's equation", defining the rate of the soil infiltration capacity recovery after a rainfall, i.e. in a drying period.
Manning's number
Describes roughness of the catchment surface, used in hydraulic routing of the runoff (Manning's formula).
5.5.4
Additional Time series
Additional runoff
Additional runoff Evaporation check box - controls if the evapo-transpiration process will be included in the runoff computations can be specified as a constant flow or specified as load based on inhabitants (PE). An additional time series for load (qload) is specified on the time series, when the flow is based on load based on inhabitants (PE>0). The flow is calculated as:
Flow =
[
PE
( ) (5.1)
Evaporation
Evaporation check box - controls if the evapo-transpiration shall be calculated based on a time series (when checked the time series is specified on the Time series page) or based on a constant loss (equal to 0.05 mm/hour).
Snow melt
Snow melt check box - controls if snow melt is included in the calculation.
The content of the snow storage melts at a rate defined by the degree-day coefficient CSnow multiplied with the temperature deficit above 0 Degree
Celsius. Typical values for Csnow is 2-4 mm/day. When snow melt is checked a time series for temperature is specified on the Time series Page.
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5.6
Flood Estimation Handbook (FEH)
5.6.1
Background
The Flood Estimation Handbook (FEH) was introduced in 1999 to replace the previous Flood Studies Report (FSR) methods for flood estimation in the UK. The FEH comes in 5 volume, with 2 associated software products.
The FEH set comprises:
1. Overview
2. Rainfall Frequency Estimation
3. Statistical Procedures for Flood Frequency estimation
4. Restatement and application of the Flood Studies Report rainfall-runoff method
5. Catchment Descriptors
The implementation of MIKE FEH is mainly concerned with Vol. 4.
5.6.2
Methods for hydrograph Generation
The following methods for computing a hydrograph have been incorporated into MIKE FEH:
i. Generation of a T-year event -Chapter 3 of the FEH handbook
ii. Generation of a Probable Maximum Flood (PMF) - Chapter 4 of the
FEH handbook
iii. Generation of an observed Flood Event - Chapter 5 of the FEH handbook
5.6.3
T-Year Event
The steps described below are used to compute a T-Year hydrograph:
256 MIKE 11
Flood Estimation Handbook (FEH)
Rainfall-Runoff Editor
257
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Table 5.1
Step Input
1
T-Year event
The catchment in question is identified from the FEH CD ROM and the catchment descriptors exported to CSV formatThe main descriptors are:
· AREA = catchment area (km2)
· DPLBAR = = mean drainage path length (km)
· DPSBAR = mean drainage path slope (m/km)
· PROPWET = proportion of time when Soil Moisture Deficit (SMD) was below 6mm in period 1961-90
· SPRHOST = Standard Percentage Runoff derived from HOST soil classification (%)
· URBEXT = extent of urban and suburban land cover
· SAAR = Standard Average
Annual Rainfall (mm)
· The Depth-Duration-Frequency rainfall descriptors: c, d1, d2, d3, e and f
Computation Reference
Vol. 5, Chap
7.
2 Compute Tp(0) - Time to peak of instantaneous unit hydrograph
(IUH).
This can be computed from
i. Catchment
LAG (Vol. 4,
Eq. 2.9)
ii. Catchment
Descriptors
(Vol. 4, Eq.2.10)
iii. Donor catchment
iv. Observations
Vol. 4, Chap
2.2.
MIKE 11
Flood Estimation Handbook (FEH)
Table 5.1
Step Input
3
T-Year event
4
5
Computation Reference
Compute delta T, time interval of unit hydrograph.
Recommended as 10-20% of
Tp(0). Computed as 20% of
Tp(0).
Vol. 4, Chap
2.2.
Compute Time to peak, Tp, of unit hydrograph.
Tp = Tp(0) + deltaT/2
Calculate Unit Hydrograph peak
(Up) and time base (TB).
Vol. 4, Chap
2.2.
Up: Vol. 4,
Eq 2.6.
Tb: Vol. 4,
Eq. 2.7.
6
7
8
Calculate design Storm duration,
D.
Calculate rainfall return period,
TR for each flood return period
TF.
Compute the D hour, TR year point rainfall (mm) = MT-Dh
This is calculated from the catchment descriptors c, d1, d2, d3, e and f.
Not Displayed.
D = Tp
(1+SAAR)/1000
Vol. 4, Chap
3.2.1, Eq.
3.1.
If URBEXT <
0.125, then TR is determined from Vol. 4, Figure 3.2.
If URBEXT
>0.125 and
<0.50, then TR
= TF
Vol. 4, Chap
3.2.2.
Gumbel reduced variate:
Vol. 2, Chap
2.3.
Eq. 2.2 - 2.4.
Y=-ln[-ln(1-
1/TR)]
(Vol. 2, Eq. 2.1)
The point rainfall is computed as a function of y and c, d1, d2, d3, e and f.
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Table 5.1
Step Input
9
T-Year event
Computation Reference
Compute storm depth P for catchment by scaling point rainfall depth with Areal Reduction Factor
(ARF)
ARF = 1 - bD-a
Where a and b are functions of the Area.
Not Displayed
Vol. 2, Chap
3.4.
Vol. 4, Chap
3.2.2.
10 Derive design storm profile. There are 2 standard profiles, the winter and the summer profile.
If URBEXT <
0.125, use winter profile.
The actual design profile is based on the standard one taking into account the catchment storm depth and duration.
If URBEXT
>0.125 and
<0.50 use summer profile.
Compute and write to output file in dfs0 format.
The profiles are defined in Vol. 2
Eq 4.2 and shown in Vol. 4
Figure 3.5.
Vol. 2, Chap
4..
Vol. 4, Chap
3.2.3.
11 Compute Catchment Wetness
Index (CWI). This is function of
SAAR.
Vol. 4, Chap
3.2.4.
Figure 3.7.
12 Compute Standard Percentage
Runoff (SPR). SPR can be computed from
· Baseflow index (Vol. 4 Eq. 2.16)
· SPRHOST
· Transfer from donor
· From observations
Vol. 4, Chap
2.3.
13 Calculate percentage runoff (PR) appropriate to the design event.
This is based on PR for the rural fraction of the catchment and scaled according to URBEXT.
Vol. 4 Eq. 2.12,
2.13, 2.14, 2.15.
Vol. 3, Chap
3.3.1.
MIKE 11
Flood Estimation Handbook (FEH)
Table 5.1
Step Input
T-Year event
14 Compute baseflow. This can be computed from
· Catchment descriptors (Vol. 4 Eq
2.19)
· Transfer from donor catchment
· From observations
Computation Reference
Vol. 4, Chap
2.4.
15 Compute the net event hydrograph by multiplying the design rain event hyetograph by PR.
Output of Step
10 multiplied with PR.
16 Compute the rapid response hydrograph by convoluting the net rainfall event hyetograph against the unit hydrograph (computed in step 5).
Vol. 4, Eq. 2.3
Vol. 4, Chap
3.3.
17 Compute total response hydrograph by adding baseflow
(Step 14) to rapid response hydrograph (Step 16).
18 Scale computed hydrograph according to Target Peak Flow.
5.6.4
Probable Maximum Flood
PMF computations are used for e.g. reservoir and dam safety studies. The main differences between PMF and T-Year hydrograph generation described in the previous section are:
· Unit hydrograph parameters
· Rainfall generation
· CWI estimation
· Contribution of Snowmelt
· Standard percentage runoff (SPR) and Percentage runoff (PR)
Unit Hydrograph Parameters
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Very simply, the time to peak of the instantaneous unit hydrograph, Tp(0), for a PMF computation is assume to be 0.67 times the standard value. This affects both the peak (Up) and time base (TB). See Vol. 4, Chap 4.2.1.
Rainfall Generation
The Probable Maximum Precipitation (PMP) hyetograph is constructed directly, not via storm depth and standard profiles as in the T-year case.
The user is required to construct the design hyetograph manually and store the profile in a dfso file.
Catchment Wetness Index (CWI)
This is now a function of the estimated maximum antecedent rainfall, which in turn is a function of the storm hyetograph. The user should make the computation (given in Vol. 4 Chap 4.3.3) and enter the value directly in the menu.
Contribution of Snowmelt
Snowmelt may contribute to both the storm depth and antecedent rainfall, and therefore the CWI. The user should define a snow melt rate (mm/h) from which both these effects can be computed. See Vol. 4, Chap 4.3.4 and example 4.1f. Output from this part is an adjusted CWI (denoted
CWI') as well as a modified storm profile in dfs0 format (as for step 10, above).
Standard percentage runoff (SPR) and Percentage runoff (PR)
If using a winter PMP, the SPR is set to a minimum of 53% to account for frozen ground. See Vol. 4 Chap 4.2.2. In addition, a revised formulation for PR is made, Vol. 4, Eq. 4.12.
Initially, the SPR is computed as for step 12, above, and subsequently checked to ensure that the value is greater than or equal to 0.53 (if a winter profile is used).
In the computation of PR, PRrural is computed from Vol. 4, Eqs. 2.13 -
2.15 and Eq. 4.12 using the SPR (just computed), the CWI (adjusted for snowmelt) and the integral over time of the design hyetograph (also adjusted for snowmelt).
MIKE 11
Flood Estimation Handbook (FEH)
5.6.5
Generation of an Observed Flood Event
In this case observed rainfall is used as input from which the resulting hydrograph can be computed. Computation of the CWI is also based on the rainfall observations. See Vol. 4, Chapter 5.
Catchment Rainfall (MAR)
Catchment rainfall is provided by the user as a dfs0 file. Please note that mean area rainfall computation is done on the time series page in the Rainfall-Riunoff editor. Following the specification of a catchment rainfall file, the period (start and end) covered by the time series will be shown. Using this information the user is required to set the design storm period, which defines the storm duration and the rainfall depth.
Storm Depth and Duration
The storm duration and depth is computed automatically from analysis of the input rainfall. Note the rainfall must start at least 5 days before the storm start time in order to compute antecedent wetness.
Storm Profile
An option should be available to allow the user to use the measured rainfall time series distribution to generate the hydrograph, or else one of the two standard profiles (summer or winter).
Observed Antecedent Catchment Wetness Index (CWI)
The CWI calculation is based on the observed rainfall record in the 5 days prior to the start of the event and the observed soil moisture deficit (SMD).
The procedure is described in detail in Vol. 4, Appendix A, section A.4.2.
SMD is defined by the user. Subsequently, CWI is computed by MIKE
FEH.
5.6.6
Results
The user may set the origin of the time axis of all the result files computed in MIKE FEH. This may be desirable if a hydraulic analysis (using MIKE
11 HD) is to be done afterwards.
The results include:
1. The design storm profile as interpreted by MIKE FEH
2. The unit hydrograph profile used to compute the hydrograph
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3. The computed hydrograph
If, for a T-Year event, multiple return periods have been specified, the result files contain multiple columns, one column for each event.
5.6.7
Validation
Once the user presses the Compute button on the Results page, MIKE
FEH starts the validation of the provided input. If the input is accepted, the model proceeds, otherwise the validation error messages are shown in the interface.
5.6.8
Log Files
An excerpt of the input and the intermediate results are found in a text with the extension .log. The file is located in the directory of the RR11 file.
In the interface, the user may indicate for each catchment whether or not a log should be created.
5.7
DRiFt
Introduction
The DRiFt module (DRiFt = Discharge River Forecast) is a semi-distributed rainfall-runoff model based on a morphological approach. The model is able to consider the topography of each site analyzed and the spatial variability of soil characteristics and rainfall patterns. Input data for the
DRiFt model is divided into three groups:
– Surface Flow parameters
– Initial Conditions
– Rainfall / Precipitation data
The development of DRiFt has been made by CIMA - Centro di ricerca
Interuniversitario in Monitoraggio Ambientale - a research institution of the Universities of Genoa and Basilicata (Italy), in cooperation with
ACROTEC S.r.l.
5.7.1
Surface flow
Parameters for calculating the surface flow are described below (see
264 MIKE 11
DRiFt
Figure 5.19
DRiFt Surface Flow parameters
Geo-morphological Parameters
DEM
The DEM (Digital Elevation Model) of the basin - prepared and saved in a two-dimensional grid-file (*.dfs2). For a better interpretation of the derived files (like draining network files, etc.), it is opportune to mask the useless parts of the territory (e.g. the sea) setting them to "no data value".
The DEM-file to be applied for a particular catchment must be selected by pressing the Browse button ‘...’. The ‘Edit’ button opens an already selected DEM dfs2-file for viewing and editing in the MIKEZero grid editor.
Threshold value AS
k
AS k
is the threshold value for a slope-area filtering procedure applied when generating the channel drainage network in the basin from the DEM.
Typical range of AS k
is 100-1.000.000 m
2
, default value for e.g. a 225m x
225m DEM resolution: 100.000 m 2 .
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Geo-morphological exponent, k
The Geo-morphological exponent, k is the exponent used in the expression for the threshold value AS k . Default value is 1.7.
Draining Network file
The draining network file is a grid-file containing some topography information in general from the DEM and additionally, the information on the channel or draining network inside the basin. The Draining network file is the grid-file which is actually used in the calculation of surface runoff.
Therefore, it is required to specify a draining network file for each DRiFt catchment prior to a simulation.
The Draining Network is created by activating the ‘Create’ button after a
DEM-filename, an ‘AS k
’-value and a ‘k’-value has been defined. Alternatively, a pre-defined network-file can be loaded by use of the ‘...’ button.
Before the creation, a name for the destination file must be chosen by clicking on the '…' button. The suggested default name of the draining network file is "catchment_name.choice.dfs2".
Other files are automatically generated together with of the draining network file (e.g. catchment_name.pnt.dfs2 representing the slope orientation, catchment_name.area.dfs2 representing the drained upstream area).
These files are used in the simulation even though they do not appear within the interface, therefore they always must be located together in the same directory. The user must pay attention to the operations which could alter this conditions (renaming, moving, deleting these files).
Catchment outlet node
The catchment outlet node is defined as the pixel (gridpoint) in the draining network where outlet from the basin occurs. The outlet node is specified by the X- and Y-coordinates (or j- and k-grid coordinates as are the standard notations for dfs2-file definitions in MIKEZero) of the gridpoint which contains the basin outlet location.
Surface Parameters
Curve Number (CN)
CN (the Soil Conservation Service Curve Number) can be specified in two ways; either as an average, constant value for the entire basin or as a distributed grid defined by a dfs2-file.
MIKE 11
DRiFt
Activating the ‘Average value’ tick-mark will activate the average value field and a constant value must be defined. De-activating the tick-mark will require a dfs2-file selection in the ‘Distributed’ field by use of the browse button.
The range of this variable is from 0 to 100.
Flow velocity in channels
Flow velocity in each area (cell) within the basin which is identified in the draining network file as ‘channel’. Contributes to the computation of a total routing time.
Default value for flow velocity on channels is 1 m/s. The normal range of the variable is from 0,1 m/s to 10 m/s.
Flow velocity on hillslopes
Flow velocity in each area (cell) within the basin which is identified in the draining network file as ‘non-channel’ or ‘hill-slope’. Contributes to the computation of a total routing time.
Default value for flow velocity on hillslopes is 0,1 m/s. The normal range of the variable is from 0,001 m/s to 1 m/s.
5.7.2
Initial conditions
Initial conditions for the DRiFt model comprises the SCS Antecedent
Moisture Content. The SCS-AMC value is specified in the DRiFt Initial
Conditions page (see Figure 5.20).
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267
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Figure 5.20
DRiFt Initial Conditions page
SCS Antecedent Moisture content
The antecedent moisture content can be defined as either a constant value all over the catchment or a distributed value (defined in a dfs2-file). Only theree values are allowed: Type I (dry condition), Type II (normal condition) and Type III (wet condition).
Default option is to use a constant value. If, however a distributed AMCvalue is required, then activate the ‘Distributed SCS Antecedent Moisture
Content’ tick-mark and select an AMC dfs2-file by use of the browse button. AMC dfs2-file must be constructed assigning to each cell numeric values 1, 2 or 3 corresponding to Type I, II or III.
5.7.3
Rainfall
The input for the rainfall-runoff simulation is supplied as rainfall (or precipitation) data. Rainfall data can be specified either as a constant value, as a timeseries or as a time-varying distributed rainfall pattern.
268 MIKE 11
DRiFt
The rainfall input is defined in the DRiFt ‘Rainfall’ page (see
Figure 5.21
DRiFt Rainfall page (Spatial distribution = Uniform)
Precipitation Rate
DRiFt utilises a spatial distributed map of precipitation as input to the computational part. It is therefore required to preprocess a rainfall map from either spatial and/or temporal distributed sources.
Spatial distribution
Spatial distribution of precipitation can be made either Uniform or Distributed. Select the required option from the Spatial Distribution combobox.
Temporal distribution
Temporal distribution of precipitation can be made either Constant (= constant value in space and time) or Time Varying.
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Based on the selected combination of spatial and temporal distribution of rainfall, different precipitation data definitions are required (see
Table 5.2
Specification of precipitation data. Requirement as function of Spatial and Temporal distribution selections.
Spatial
Distribution
Uniform
Uniform
Distributed precipitation maps
Temporal
Distribution
Constant
Time Varying
Time Varying
Required precipitation data definition
Constant value for precipitation rate
[mm/hours]
Time series file (dfs0) of precipitation as rainfall intensity
[mm] or rainfall intensity
[mm/hour]
Time varying grid-file (dfs2) of precipitation as rainfall [mm]
Constant precipitation rate
Here the constant precipitation rate is defined [mm/hour].
TS-File
With a selection of uniform spatial distribution and time varying temporal
distribution as presented in Figure 5.21, it is required to select a time
series file (dfs0-file) with rainfall data in the ‘TS-file’ filename field.
Precipitation can inserted in two different ways:
– as "rainfall" [mm] and TStype = "mean step accumulated"
– as "rainfall intensity" [mm/hour] and TStype = "instantane-
ous"
Rainfall file
With a selection of distributed precipitation maps as presented in
Figure 5.22, it is required to select a time varying grid-file (dfs2-file) with
rainfall data in the ‘Rainfall file’ filename field.
Here precipitation is always treated as "rainfall" [mm], "mean step
accumulated"
MIKE 11
DRiFt
Create new distributed precipitation maps
DRiFt includes a possibility for generating a time varying gridbased precipitation input file from a number of single raingauges observations by use of spatial interpolation. If the rainfall pattern must be distributed and no rainfall file exists then by activating this check-box, DRiFt will generate a time varying distributed file with the filename as specified by the user in the ‘Rainfall File’ filename field.
In case the ‘Create new distributed precipitation maps’ feature is enabled, it is required to specify Raingauges definitions in the table below the checkbox.
Rainfall station specification table
Rainfall stations (raingauges) definitions for the spatial interpolation feature in DRiFt is given in this table. The information required for the interpolation is:
– the location of the raingauge station in the basin defined by plan coordinates (X and Y),
– a timeseries file (dfs0-file) with rainfall measurements from the specific station. Use the Browse button to select the required dfs0file.
– additional, optional information in the table is the possibility to specify a text-string identifier for each rainfall station.
To start the definition of raingauges stations in an empty raingauges table, click on the ‘Edit’ column-button and thereafter press <TAB>. Alternatively, it is possible to select from the ‘Grid’ option in the Main Menu Bar the ‘Insert line’ option (after one of the column-buttons has been activated). Thereby, a new line will be appended to the table and rain gauges specifications can be made.
Every time a new raingauge definition must be added, it is possible to add a new line to the table by using the Tabulator when the cursor is located in the last column of the table.
An example of definition of three raingauges stations is presented in
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272
Figure 5.22
DRiFt Rainfall page (Spatial distribution = Distributed)
Interpolation type
Interpolation options for generation of time varying distributed precipitation maps are: ‘Thiessen’ and ‘Inverse squared distance’. Select the desired interpolation type from the Interpolation type combo-box.
Precipitation timestep
The precipitation time step is the temporal resolution of the new distributed maps [seconds]. In order to exploit the whole available information, it is recommended to set the precipitation time step on the same value of raingauges measurements resolution.
Create precipitation maps
This action-button creates the required distributed precipitation maps for the DRiFt runoff calculations. The distributed rainmaps are required for all DRiFt calculations and it is therefore requested for the user to prepare a rainmap for all catchments.
MIKE 11
Time Series
The precipitation map will be created here as "rainfall" [mm], "mean
step accumulated"
The file containing the rainmap is a dfs2-file with a filename depending on the selection of spatial distribution (uniform or distributed). For a selected uniform spatial distribution the filename will be ‘Rainmap+Catchment-name’.dfs0. If a distributed spatial distribution has been selected then the Rainmap will be saved in the file as specified in the
‘Rainfall file’ edit-field.
5.8
Time Series
The Time series page serves two purposes: Input of time series and calcu-
lation of weighted time series (see Figure 5.23)
Rainfall-Runoff Editor
Figure 5.23
Time series Page.
273
274
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Input of time series
The input time series for the rainfall-runoff simulations are specified on this page. The time series are used as boundary data to a MIKE 11 simulation. Following data types are used:
Rainfall
A time series, representing the average catchment rainfall. The time interval between values, may vary through the input series. The rainfall specified at a given time should be the rainfall volume accumulated since the previous value.
Evaporation
The potential evaporation is typically given as monthly values. Like rainfall, the time for each potential evaporation value should be the accumulated volume at the end of the period it represents. The monthly potential evaporation in June should be dated 30 June or 1 July.
Temperature
A time series of temperature, usually mean daily values, is required only if snow melt calculations are included in the simulations.
Irrigation
An input time series is required to provide information on the amount of irrigation water applied, if the irrigation module is included in a NAM simulation
Abstraction
Groundwater abstraction can be included in NAM simulations for areas, where this is expected to influence e.g. the baseflow. The data should be given in mm.
Radiation
A time series of incoming solar radiation can be used as input to the extended snow melt routine.
Degree-day coefficient
A time series of seasonal variation of the degree-day coefficient can be specified as input to the extended snow melt routine.
Observed Discharge
A time series of observed discharge values can be specified and used for model calibration. The observed discharge must be specified when automatic calibration is included.
MIKE 11
Time Series
The selection of the observed discharge will automatically enable additional output which includes a calibration plot with comparison of observed and simulated discharge and calculation of statistical values. See
Calculation of Weighted time series
This calculation usually needs only be made once. Once the calculation is made the result are stored in time series that can be used for subsequent rainfall-runoff modelling runs.
If the rainfall data, weights or number of catchments changes the calculation must be repeated.
The Mean Areal Weighting calculation can be performed in two ways.
1 Directly within the Rainfall Runoff Editor. From the top toolbar menu select Basin Work Area and the Calculate mean precipitation. The calculation is made without requiring a model run.
2 During a simulation. A new simulation is started in the Simulation Editor: If the weighted time series is ticked, the Mean Area weighting calculation is carried out as part of the model run.
It is recommended to use option 1.This will ensure that the available periods of the input files known in the simulations editor.
After having calculated the weighted time series once the calculation can be disconnected when removing the tick mark for weighted time series.
Mean Area Weighting
Weighted Average combinations
Where complete time series for all stations are available for the entire period of interest only one weight combination is required. Where data is missing from one or more stations during the period of interest different weight combinations can be specified for different combinations of missing data.
It is not necessary to specify weight combinations for all possible combinations of missing stations. For each calculation, the Mean Area Weighting algorithm will identify estimate weights which best represent the actual combination of missing data. In most cases only one set of weights need to be specified. The Mean Area Weighting algorithm will automatically redistribute weights from missing stations equally to the stations with data.
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Alternatively, the user may specify the weight to be used for specific combination of missing data. For each such catchment, a suitable weight should be specified for the reporting stations and a weight of “-1.0” given for the non-reporting station(s), including missing data.
Distribution in time
If data is available from stations reporting at different frequencies, e.g. both daily and hourly stations, the Distribution in time of the average catchment rainfall may be determined using a weighted average of the high-frequency stations. You may, for example, use all daily and hourly stations to determine the daily mean rainfall over the catchment and subsequently use the hourly stations to the distribute (desegregate) this daily rainfall in time. Different weight combinations for different cases of missing values may be applied also to this calculation of the distribution in time.
Time fixed combinations
It is possible to specify fixed periods with different combinations. The periods are specified from the menu bar (select: Parameters | Time-fixed combinations). To enable calculation: Tick mark in the check box on the time series page.
Deleting stations
Stations which are not longer valid in the weight combinations are removed from the editor by deleting the station number in the editor.
Delete values
The delete value used in the time series indicating periods with missing data is usually specified with the default delete value ‘1e-30’. The default delete value can be changed via the MIKEZero Data Utility tool.
5.9
Parameters menu
The parameters menu contains a number of items mainly relating to the
UHM models Storage Function, Quasi Linear Storage Function, Nakayasu, Rational method, and Kinematic Wave.
5.9.1
Enlargement ratio
The rainfall specified in the time series page can be enlarged by a factor.
Three factors, each with a duration for which they should apply, can be specified.
276 MIKE 11
Basin View
5.9.2
Loss Parameters
For the Nakayasu and the f1-Rsa loss method a number of sets of parameters can be specified. Later when specifying the loss method for a UHM catchment a set of parameters from this dialog can be selected by refering to the row number in the dialog.
5.9.3
Land use definitions for QLSF method
A number of sets of parameters relating to the UHM method quasi linear storage function method can be specified. Later when defining QLSF catchments the user refers to the row number of this dialog when defining the precentage of area covers by land use category.
5.9.4
Default values for specific method
A number of parameters which can be specified globally only, i.e. they allpy to all catchment of the given type, are available. See technical reference for more details on each parameter.
5.9.5
Time-fixed combinations
Normally the mean area rainfall calculator selects the weight combination based on the availability of the rainfall stations. However, if desired the selection of the combination can be made only of time. On this dialog the time periods for which each of the combinations should be applied can be specified. Time-fixed combination are activated by slecting the check-box on the time-series page.
5.9.6
MAW merged output file.
Normally, the mean area rainfall for each catchment is saved in separate file. If desired these files can be combined into one file. This is selected on this dialog, and the file name for the merged file is specified.
5.10 Basin View
The Basin View provides an graphical interface for some useful rainfallrunoff modelling tools providing facilities to: z z z
Digitise catchment boundaries and the location of rainfall stations
Calculate catchment areas
Calculate weights used for mean area rainfall calculation
Rainfall-Runoff Editor
277
Rainfall-Runoff Editor
The Basin View is as default not activated when a Rainfall Runoff file is opened or created. It is often not required to activate the Basin View for preparation of the RR-file.
5.10.1 Activating the Basin View
To activate the Basin View within MIKE 11 select View and Basin View from the top menu bar. When opening a new Basin View the extent of the basin area is defined in the Define Basin Area dialog.
Figure 5.24
Define Basin Area Dialog.
When opening a new Basin View at least one catchment (usually the default) must exist in the Rainfall Runoff Tabular View, which must be open same time as the Basin View. This initializes the Rainfall Runoff
Editor. The default catchment can afterwards be deleted from the catchment page in the Tabular View, such as the catchments in the Basin View and on the Tabular View are the same.
5.10.2 Importing Layers
The layer management tool is used to import a graphical image used as background in the Basin View (select “Layers | Layer management” from the menu bar). The graphical image is georeferenced in the image coordinates dialog when importing the layer.
5.10.3 Basin Work Area
The Basin Work Area dialog selected from the top menu bar contains fol-
lowing facilities (see Figure 5.25).
278 MIKE 11
Basin View
Rainfall-Runoff Editor
Figure 5.25
Basin Work Area.
Import Basin Definitions
Import of predefined Basin Definitions from a file with the format:
1 478.2 98.0 c:\data\station1.dfs0
1 station1
2 488.5 110.1 c:\data\station1.dfs0
3 462.5 113.2 c:\data\station1.dfs0
4 425.0 151.9 c:\data\station1.dfs0
4 point4
Line Format:
[station index] [x] [y] [full path to TS file] [TS item no.] [station name].
The lines are repeated for each last station.
2 rain2
3 place3
Import Station Definitions
Import of predefined Location of Rainfall Stations from a file:
1 478.2 98.0
2 488.5 110.1
3 462.5 113.2
4 425.0 151.9
Line 1 - 4 : Station number, (x,y)-coordinates.
279
Rainfall-Runoff Editor
The lines are repeated until the last station.
Export Catchment Polygons
Export of Catchment boundaries to a file.
Thiessen Options
Preparation of Thiessen Weights takes place from the “Thiessen Option”- dialog. Select number 1 for the first combination and press OK (see
Figure 5.26). Thiessen weights have now been prepared on the Time
series page (see Figure 5.23, Time series page in the Rainfall Runoff Edi-
tor).
280
Figure 5.26
The Thiessen Option dialog.
Apply the weight “-1.00” (for stations with missing data) on the timeseries page before calculating of other combinations.
Showing Thiessen polygons for a catchment on the Basin View:
1 Press the Thiessen icon ( ) on the Basin View toolbar.
2 Right click on the basin view.
3 Select combination number and left click on the catchment.
Isohyetal Options
The Isohyetal Option is used as a post processing tool to calculate average catchment rainfall for a fixed period based on isohyetal lines. The tool has no link to data on the Timeseries page in the Rainfall Runoff Editor. It should therefore be noticed that the Isohyetal Option can not be used to prepare weights and time series of mean area rainfall used as input to the rainfall-runoff calculation. Select the Isohyetal Options to activate the Iso-
hyetal Option dialog (see Figure 5.27). The dialog has the following
pages:
1 Preparation of periods.
2 Grid Interpolation
MIKE 11
Basin View
3 Isoline Options
4 Calculated catchment rainfall based on interpolated isolines
To see the Isolines on the Basin View: Press the Isoline icon on the Basin
View toolbar ( ).
Rainfall-Runoff Editor
Figure 5.27
Isohyetal Options dialog
Calculate Mean Precipitation
After having prepared the Thiessen weights (see Figure 5.23, Time series
page in the Rainfall Runoff Editor), this option is used to calculate the weighted time series used as catchment mean rainfall for a Rainfall-runoff calculation.
Combination Definitions
Options used to View different Thiessen Polygons on the Basin View.
Graphical Settings
Graphical Settings can be modified from the Graphical Settings Dialog
The “Graphics” page is used to adjust display options for the following graphical objects:
– Basin Web Objects (active when editing or deleting objects)
– Catchment Objects
281
Rainfall-Runoff Editor
– Station Objects
– Thiessen Objects
The page “Mouse” is used to adjust the digitizing distance and the Mouse sensitivity for digitizing on the screen.
282
Figure 5.28
Graphical Settings.
Resize Working Area
The working area on the Basin View can be resized from this option.
Delete selected items
After selection a catchment boundary (press the delete boundary icon: and click on the actual boundary) or selecting a rainfall station (press the default mode icon: and click on the actual station) the item can be deleted either by using this option or by pressing the delete button.
Create Polygons
After having digitized the catchment boundaries this option is used to create catchment polygons (alternatively press the Create Polygon Catchments icon: ). Each catchment will be created in the Rainfall Runoff
Editor, including an automatic calculation of the area.
Copy Metafile to clipboard
The Basin View is copied to a the clipboard.
MIKE 11
Basin View
Save View to Metafile
The Basin View is saved as a Metafile (*.emf). Afterwards this Metafile can be used as background image in the River Network Editor.
5.10.4 Preparing Catchments
Defining Catchment Boundaries
Defining and editing boundaries is mainly undertaken using the add catchment boundary button ( ) from the Basin View toolbar. The first catchment boundaries are defined as a set of points connected by straight lines forming a polygon. To define the boundaries press the add catchment boundary button and start digitising the first catchment boundary. To close the first catchment boundary polygon double click on the mouse. Digitising of additional boundaries is initiated when selecting the add catchment boundary, clicking on the mouse with the cursor placed close to an existing boundary point. The first boundary line for the second catchment is therefore from the closest existing boundary points to the cursor points.This boundary is closed when double clicking on the mouse close to an existing boundary point.
Deleting Catchment boundaries
Existing catchment boundaries can be deleted as follows:
1 Press the “Delete Boundary”-icon ( ).
2 Click on the actual boundary to be deleted.
3 Press the delete button.
Testing catchment
After having prepared the catchment boundaries the “Test fill catchment”icon ( ) can be used to test the validity of the digitized catchment polygons.
Create Polygons
Catchments are created within the Rainfall Runoff Editor using the “Create Polygon Catchments”-icon ( ) after having digitized the catchment boundaries. Each catchment will be created in the Rainfall Runoff Editor, including automatic calculation of the area. Catchment names can be modified in the Rainfall Runoff Editor.
Rainfall-Runoff Editor
283
Rainfall-Runoff Editor
5.10.5 Inserting Rainfall Stations
Defining Stations
New rainfall stations are created with the “Create New Stations” icon
( ). Click in the Basin View on the Station Location and use the “Edit
Station”-dialog to select the time series and select the name for the Rain-
fall station (see Figure 5.29).
Figure 5.29
Edit Station Dialog.
Deleting Stations
Rainfall stations are deleted from the Basin View as follows:
1 Press the default mode icon:
2 Click on the actual station.
3 Press the delete button.
Editing Stations
Stations are modified in the “Edit Station”-dialog as follows:
1 Press the default mode icon:
2 Right click on the actual station and select “Edit Station”.
5.10.6 Preparing Thiessen weights
Thiessen weights are prepared from the menu bar (Basin View | Thiessen
Options).
284 MIKE 11
Result Presentation
Figure 5.30 shows an example of a Basin View for two catchment show-
ing the catchment boundaries, 7 rainfall stations and the Thiessen polygons for all 7 stations.
Figure 5.30
Basin View with catchment boundaries, rainfall stations and Thiessen polygons.
5.11
Result Presentation
Results
MIKE11 generates two Rainfall Runoff Result files. The first result file contains simulated runoff and net precipitation. The second, additional result file (RRAdd) contains time series of all calculated variables, such as the moisture contents in all storages, the baseflow etc., and can be very useful during model calibration. The results of the simulation can be generated in two formats, either as RES11 or DFS0 filetype. The format of the result file should be selected before running the simulation. Three facilities are available to plot and analyze the results of a rainfall-runoff simulation:
1. MikeView. To apply MikeView for result analysis during calibration,
use RES11 as result file type. Plot layouts can be generated (and saved) in
Rainfall-Runoff Editor
285
Rainfall-Runoff Editor
MikeView for comparing simulated and observed flow while displaying e.g. the Root Zone storage variation, the snow storage, the rainfall etc.
2. MikeZero Time series Editor The time series editor can also be used
to view and compare simulated and measured results and to export results to e.g. a spreadsheet for further processing. The result file should then be given a DFS0 extension.
3. MikeZero Plot Composer. The MIKEZero Plot composer, which also
uses DFS0 files, is suitable for arranging final plots for presentation in reports and can also be used in the calibration procedure.
Summarised output
MIKE 11 generates as standard a table with yearly summarised values of simulated discharge. The table is stored as the textfile “RRStat.txt” in the current simulation directory. The table is extended with observed discharge for catchments, where the time series for observed discharge have been specified on the Timeseries Page. This includes a comparison between observed and simulated discharge with calculation of the water balance error and the coefficient of determination.
The output from a NAM catchment is extended with summarised values from other components in the total water balance for a catchment.
Figure 5.31 shows an example on the content of summarised output.
286
Figure 5.31
Example of contents of summarised output from a NAM catchment with observed discharge included.
MIKE 11
Result Presentation
Calibration Plot
A calibration plot will automatically be prepared for catchments, where the time series for observed discharge have been specified on the Time series Page and the selection of calibration plot has been ticked off on the catchment page. The calibration can be loaded from the Plot composed and is saved in the subdirectory RRCalibration with the file name: Catchment-name.plc. The time series in these plots are also available in DFS0 format in the subdirectory RRcalibration with the file name: Catchment-
name.dfs0. The plot shows following results (see Figure 5.32):
Rainfall-Runoff Editor
Figure 5.32
Example on a Calibration Plot
– Comparison between observed and simulated discharge.
– Comparison between accumulated series for observed and simulated discharge.
– Values for water balance error and coefficient of determination.
It should be noticed that the calibration plot requires the results saved for each simulation timestep (See Simulation editor, Results Page).
287
Rainfall-Runoff Editor
A combined catchment has no input timeseries and is therefore not represented on the Timeseries page. The observed discharge for a combined catchment is therefore included as the observed discharge for the previous catchment on the Timeseries Page.
5.12 A Step-by-step procedure for using the RR-Editor
This section illustrates the steps required to create a rainfall-runoff model setup, and then carry out an auto calibration and model simulation The example is based on the Skawa catchment, which is located in the Upper
Vistula Basin in Poland. The figures presented in this chapter describing the Rainfall Runoff Editor are taken from this example. The following step were performed:
1 Opening of a new MIKE11 RR - Parameter file. A catchment must
be defined in the first “Insert Catchment”-dialog (see Figure 5.4). This
catchment is used to initialize the Rainfall Runoff Editor for the Basin
View.
2 Activating of the Basin View (select View | Basin View).
3 Import of a background images (select Layers | Layers management). The imported image was prepared and geo-referenced from an
ArcView application.
4 Digitising of catchment boundaries. The catchment was subdivided into two sub-catchments defining the Upper and Lower part of the
Catchment (see Section 5.10.4).
5 Creation of polygon catchments (see Section 5.10.4), which includes
the preparation of the two NAM sub-catchments in the Rainfall Runoff
Parameter file with automatic calculation of the catchment areas.
Default catchment names are automatically assigned to each catchment. The names on the two catchment were modified to
SKAWA_UPP and SKAWA_LOW and the default catchment was deleted from the Catchment Overview.
6 Setup of a combined catchment. A Combined catchment was defined
as the sum of the two sub-catchments (see Figure 5.3).
7 Inserting of the rainfall stations. Stations included in the calculation of catchment rainfall were included in the Basin View (see Section
8 Preparation of Thiessen Weights (see Section 5.10.3, Thiessen
Options). The calculated Thiessen Weight Polygons are shown on
Figure 5.30, which also shows the two sub-catchments. The weights
288 MIKE 11
A Step-by-step procedure for using the RR-Editor which were automatically transferred to the Time series Page are
9 Calculation of Mean Precipitation. The Weighted timeseries were calculated based on the weights prepared as described in the previous step.
10 Setup of other input time series. Input Time series for Evaporation,
Temperature and Observed Discharge were included on the Time series
11 Setup of NAM snow melt parameters. The Skawa catchment is located in the mountains ranging from 200-1500 m above sea level. and the runoff is therefore influenced from snow melt for part of the year. The NAM setup was prepared with the extended snow melt com-
ponent including elevation zones (see Figure 5.7). Areas of the eleva-
tion zones were prepared from a Digital Elevation Model included in an ArcView application. Areas were afterwards copied to the “Elevation zone”-dialog via the clipboard. Temperature corrections were
finally calculated using a fixed temperature lapse rate (see Figure 5.8).
12 Initial Conditions. The simulation starts from the beginning of a year with relative high moisture content in the soil. The Initial Conditions for the Upper and the Lower zone were therefore estimated to respec-
tively 100% and 90% of maximum capacity (see ).
13 Setup of Autocalibration for the upper catchment. Estimation of parameters in the upper catchment were based on the NAM auto calibration routine. The auto calibration was based on minimising the
Overall Water Balance error and the Overall Root Mean Square error
with a maximum of 2000 iterations (see Figure 5.12).
14 Start of simulation editor. After having saved the Rainfall Runoff
Parameters, a MIKE11 simulation editor was opened. The Input page includes the RR Parameter file and the default boundary file (see
Figure 5.1). The Simulation period was prepared from the Apply
default button and a time step on 12 hours were found appropriate for
the simulation (see Figure 5.2).
15 Estimation of RR-parameters for the lower catchment. The parameters for the lower catchment were estimated based on results from the auto calibration of the upper catchment and the knowledge on a lower response and higher storage capacity for a catchment close to the flood plains compared to the more hilly upper catchment. Parameters in the
Surface-Rootzone and Ground water are shown on Figure 5.5 and
Figure 5.6. The values for the 3 most important parameters are (in
bracket values for the upper catchment): Maximum water content of rootzone: 200 mm (100 mm), Runoff coefficient: 0.7 (0.83) and Time
Constant Overland flow: 13.6 hours (20 hours).
Rainfall-Runoff Editor
289
Rainfall-Runoff Editor
16 Presentation of Results. Results from the simulation were finally
compared in tables and on plots. Figure 5.31 shows example on sum-
marised output from the upper catchment, while Figure 5.32 shows the
calibration plot for the upper catchments
290 MIKE 11
H Y D R O D Y N A M I C E D I T O R
291
292 MIKE 11
Quasi Steady
6 HYDRODYNAMIC EDITOR
The Hydrodynamic parameters editor (HD-editor) is used for setting supplementary data used for the simulation. Most of the parameters in this editor have default values and in most cases these values are sufficient for obtaining satisfactory simulation results. The editor has a number of tabs which are listed below and described in the following: z z z z z z z z z z z z z z z z z z
Flood Plain Resistance (p. 301)
Bed Resistance Toolbox (p. 306)
W. L. Incr.- Sand Bars (p. 328)
6.1
Quasi Steady
Various parameters required for the quasi steady simulation to be carried out are set here.
Hydrodynamic Editor
293
Hydrodynamic Editor
Figure 6.1
The Quasi Steady property page.
6.1.1
Computational parameters
In order to optimize the convergence parameters with respect to accuracy and computational time it is recommended that the parameters be adjusted to obtain a satisfactory solution for low flow conditions. This will lead to accurate results for higher flow conditions as well.
The optimization is carried out by running the hydrodynamic model for constant low flow conditions until steady conditions are obtained. These results can then be compared with those obtained using the quasi-steady model. It is emphasized that the parameters are 'model specific', i.e. each model setup and associated flow condition requires individual parameter optimization.
Relax
Weighting parameter used in the quasi-steady solution. For single branches without bifurcation the value should be 1. In more complex systems the value should be less than 1.
294 MIKE 11
Quasi Steady
Target_Branch
Computed water levels/discharges are shown on the screen at each iteration for branch number equal to ‘Target Branch’. No computations are shown if ‘Target Branch’ is negative.
Beta_Limit
Factor used to avoid underflow in ‘horizontal’ branches.
Fac_0
Factor used to control the stop criteria for the discharge convergence test.
Qconv_factor
Q convergence factor used in the stop criterion for the backwater computation iterations.
Hconv_factor
H convergence factor used in the stop criterion for the backwater computation iterations.
Min_Hconv_In_Branch
Minimum stop criterion to avoid underflow.
Q_struc_factor
Q structure factor: Used to determine the discharge at structures where a slot description is introduced due to zero flow conditions.
H_stop
Stop criteria in the water level convergence test. Used also by the quasi two dimensional steady state solver with vegetation as the convergence criteria in the outer loop.
6.1.2
Steady state options
The steady state options are accessed by setting the switch ‘Use energy equation’. This also indicates that the options are only available for steady state flow situations using the energy equation as the governing equation.
Allow upstream slope
This switch allows solutions where the water surface is sloping in the opposite direction of the flow. If this switch is off the solver will project the downstream water level to the upstream location and add 1 mm in situations where the water level is sloping in the opposite direction of the flow. Only turn off in situations where the calculated water level does not seem to be within an acceptable range.
Hydrodynamic Editor
295
Hydrodynamic Editor
No suppression of convective term
In some cases where the flow is in or close to the super critical range the solution algorithm may have trouble converging. This is handled by
MIKE 11 through the introduction of a suppression term which varies with the Froude number. So that for full super critical flow the convective terms in the governing equation are fully suppressed. If this suppression is not desired please set this switch to on.
Model contraction and expansion losses
This switch will allow the inclusion of expansion and contraction losses in the energy equation. When this is activated the lower part of the page should be used to input the contraction and expansion loss coefficients.
Note that the contraction/expansion loss criteria is based on the difference in the velocity head upstream versus downstream.
Velocity distribution coefficient based on conveyance
By default the velocity distribution coefficient used by MIKE 11 is 1 (user defined under default values). Using this switch the velocity distribution coefficient will be calculated based on the conveyance distribution in the cross section.
Friction slope evaluation
This option allows the user to select the method for calculation of the friction slope. Five options are available which are documented in the reference manual.
6.1.3
Contraction and expansion loss coefficients
If the user has selected to model contraction and expansion losses the coefficients must be specified. The user may choose to only give global values which are given in the top two fields above the table. If the user would like to specify either values throughout or at selected locations the lower table should be used. Note that by the use of the button on the right
"Load branch and chainages" the table can be populated with all h-point locations in the set-up, the user then simply edits the parameters to be used at the different locations.
6.2
Reach Lengths
The Reach lengths page is ONLY for use with the steady state energy equation switch found under the Quasi Steady State page. The reach lengths are used in evaluation of the friction loss from one cross section to the next. For unsteady simulations the reach lengths are ignored.
296 MIKE 11
Reach Lengths
In MIKE 11 cross sections are viewed looking downstream. Downstream is per definition the direction of increasing chainage. This definition of downstream is independent of the flow direction and is used throughout by the Graphical User Interface.
On the Reach lengths page the user specifies the reach lengths of the left and the right overflow banks in the downstream direction (increasing chainage). Note that the reach lengths are to be specified at all cross section locations except for the cross section with the highest chainage in a branch (the area downstream of such sections is either a node/junction or beyond the model area). The reach lengths are defined as the distances to the next downstream cross section (next chainage). Please refer to fig. 1 below. As an aid to the user the "Load branch and chainages" button will populate the table with all rivers and h-point locations. Please note that the functionality of this button is only available if the simulation file is open and the data from the cross section and network editors are accessible.
Since the use of reach lengths is based on raw data the method requires that there exist cross sections at all h-points in the grid. If this is not the case please insert cross sections or increase max-dx in the network editor to avoid the code generating interpolated h-points at run time. The grid generating function in the network editor can be used to check whether cross sections are present at all h-points
Hydrodynamic Editor
Figure 6.2
Reach length definition.
The reach lengths to be specified at cross section with chainage X n
is
shown in Figure 6.2. The reach lengths indicate the distance on the flow
banks from the current cross section (X n
(increasing chainage). L
Right Overflow Bank
LOB
) to the next cross section
: Length Left Overflow Bank, L
ROB
: Length
297
Hydrodynamic Editor
6.3
Add. Output
A number of simulated parameters can be selected for storage in an additional output result file (with the file name extension 'RES11'). The parameters are saved for each save step at each h/Q point of the river system.
Time series and longitudinal profiles of the parameters can be viewed in the same way as normal MIKE11 result files.
298
Figure 6.3
The additional output property page.
Structures
Structure flow, area and velocity. In case of control structures the gate level is also stored.
Velocity
Velocities are calculated as the discharge divided by the cross sectional area.
Discharge
The discharge calculated at h-points is a weighting of up- and downstream discharges calculated at Q-points.
Slope
The free water surface slope.
MIKE 11
Add. Output
Cross section area
The area of flow in the cross section. At computational H-points where no cross section is present the area is linearly interpolated from upstream and downstream areas.
Top width
The channel width at the free surface level.
Radius
The resistance radius.
Resistance
The cross-sectional resistance (resistance number multiplied by the resistance factor).
Conveyance
The conveyance
Froude number
Defined as:
F
=
A g b s
(6.1)
Where F is the Froude number, Q the discharge, A the cross sectional area,
g the acceleration due to gravity and b
s
the channel width at surface.
Volume
The volume calculated around the H-grid point.
Total: The total water volume for the river system.
Flooded Area
H-points: The flooded area of the water surface between two neighbouring
Q-points.
Total: The total surface water area for the river system.
Hydrodynamic Editor
299
Hydrodynamic Editor
Mass Error
The mass error is defined as the difference between the volume calculated in the model and the true volume. At nodal points with more than two connections the mass error is distributed uniformly between each connection.
Total: The total mass error for the river system.
Accumulated Mass Error
The sum of the ‘Mass error’ in time and space. Generally, the mass error can be reduced by increasing the number of iterations per time step, reducing the time step, and or by increasing the resolution of the cross-sections.
NOTE! Some cross-sections can cause mass-balance problems due to
large contractions. These problematic cross-sections can be detected by selecting the mass error item calculated for each grid point.
Lateral Inflows
Lateral inflows due to boundary conditions, catchment runoff, Flood forecasting updating or coupling to MIKE SHE.
Water level slope
Water level slope at discharge points.
Energy level slope
Energy level slope at discharge points.
Energy level
Energy level at water level points.
Bed shear stress
The bed shear stress at water level points given as
τ
=
------(6.2) where E is the energy level and x is the longitudinal coordinate along the river.
6.3.1
Additional output for QSS with vegetation
Note that when utilising the quasi two dimensional steady state with vegetation module, additional output is based on the processed data which does not take the effect of dead water zones or vegetation zones into account.
300 MIKE 11
Flood Plain Resistance
Additional data for these calculations can be obtained by setting the following switch in the “mike11.ini” file:
CREATE_QSSVEG_VELOCITY_FILE=ON
With this setting 8 .txt-files are generated and saved in the working directory i.e. where the simulation file is stored. The files are titled: z z z z z z z z
QSSVEG_velocities: Velocity and area of the individual panels.
QSSVEG_velocities_add1: Energy slope, low water channel width, high water channel width, Radius, wetted perimeter and Manning’s n of the individual panels.
QSSVEG_velocities_add2: Height of water/water interface, water/vegetation interface of the individual panels.
QSSVEG_velocities_add3: Mixing coefficients of the individual panels.
QSSVEG_velocities_add4: Shear forces of the individual panels normalised with
ρ.
QSSVEG_junctions: The appropriate parameters used for obtaining the water level increment due to the junction and the water level increment in the channels meeting at the junction.
QSSVEG_sandbars_curves: Water level increments due to sandbars and river curvature.
QSSVEG_bridges: The water level increments due to bridges.
6.4
Flood Plain Resistance
The flood plain resistance numbers are applied above the ‘Level of divide’ specified in the raw cross section data (.xns11 files).
The global resistance number is applied on all flood plains unless local values are specified. Local values are linearly interpolated at intermediate chainage values. The resistance number value -99 indicates that the flood plain resistance should be calculated from the raw data in the cross-section data-base.
Example (Figure 6.4): In ‘RIVER 1’ the resistance on the flood plains is
globally calculated on the basis of the raw cross section data. However, between chainage 5000 m and 10000 m an alternative flood plain resistance is applied. The resistance number on the flood plains in this reach varies linearly between 25 and 30.
Hydrodynamic Editor
301
Hydrodynamic Editor
Figure 6.4
The Flood Plain Resistance property page.
6.5
Initial
Initial conditions for the hydrodynamic model are specified on this page.
The initial values may be specified as discharge and as either water level or water depth. The radio button determines whether the specifications are interpreted as water level or depth.The global values are applied over the entire network at the start of the computation. Specific local values can be specified by entering river name, chainage and initial values. Local values will override the global specification.
Example (Figure 6.5): The global water depth and discharge have been
specified as 5.00 and 1.400 respectively. Local values have been specified in the branch "RIVER 1". The local initial water depth vary from 5.70 to
5.00 with a linear relationship between chainage 0 and 3000. The discharge also varies between 1.000 and 1.400 with a linear relationship over the 3000 branch length.
302 MIKE 11
Wind
Figure 6.5
Initial value tab
6.6
Wind
Wind fields can be applied to the entire model network using the wind property page of the HD editor. The property page contains an "on/off" switch a global wind factor and a table of local wind factors. A wind field is applied globally to the model using a hydrodynamic boundary file
(.bnd11) and can be scaled by using the global and local factors section.
Note that the friction factor is only applicable to startified flows or MIKE
12 applications.
Example (Figure 6.6): The global wind factor is set to 0.70. It varies line-
arly from 0.70 to 0.30 in the branch named "RIVER 1" from chainage 0 to
5000.
Hydrodynamic Editor
303
Hydrodynamic Editor
Figure 6.6
Wind tab.
6.7
Bed Resistance
Two approaches may be applied for the bed resistance. Either a uniform or a triple zone approach can be specified.
6.7.1
Uniform approach
The bed resistance is defined by a type and a corresponding global value.
Local values are entered in tabular form at the bottom of the editor.
There are three resistance type options:
1 Manning’s M (unit: m 1/3 /s, typical range: 10-100)
2 Manning’s n (reciprocal of Manning’s M, typical range: 0.010-0.100)
3 Chezy number.
The resistance number is specified in the parameter ‘Resistance Number’.
This number is multiplied by the water level depending ‘Resistance factor’ which is specified for the cross sections in the cross section editor
(.xns11 files) to give a resulting bed resistance.
Example (Figure 6.7): A global resistance (Manning’s M type) of 30 is
specified. In the branch "RIVER 1" local resistance numbers are specified between chainages 0 and 21000 m. The resistance number at intermediate chainage values is calculated linearly.
304 MIKE 11
Bed Resistance
Figure 6.7
Uniform approach for implementation of the bed resistance.
6.7.2
Triple zone approach
The Triple Zone Approach offers a possibility for the user to divide the river sections in three zones with different bed resistance values. These zones represent the vegetation free zone in the bottom of the profile, a vegetation zone on banks etc. and a zone for description of flow over
banks and flood plains etc. as indicated in Figure 6.8
Hydrodynamic Editor
Figure 6.8
Triple Zone division of cross section
Zone separator lines must be defined in the User Defined Markers page
(see description in Activation of Bed resistance Triple Zone Approach
305
Hydrodynamic Editor
Global and local values of bed resistance for each zone can be specified as described for the Uniform approach.
Due to the special description in the friction term in the higher order fully dynamic wave description, the triple zone approach is only available for fully dynamic and diffusive wave descriptions.
6.7.3
Vegetation and bed resistance
Only few detailed investigations have been made to establish relationships between flow resistance and vegetation growth. A quantitative evaluation of the influence of vegetation on the flow resistance has been performed in
a few Danish gauging-programmes. These are referred to in A.1 Flow
Resistance and Vegetation (p. 445).
6.8
Bed Resistance Toolbox
306
Figure 6.9
The Bed Resistance Toolbox property page.
The bed resistance toolbox offers a possibility to make the program calculate the bed resistance as a function of the hydraulic parameters during the computation by applying a Bed Resistance Equation.
Five options are available in the Bed Resistance Equation combo box: z
Not Active
Bed resistance values used in the computation are those specified in the
Bed Resistance page (Uniform or Triple zone approach)
MIKE 11
Bed Resistance Toolbox z n = 1/M = a*ln(VR)^b
The bed resistance is calculated as a function of ln(velocity*Hydraulic
Radius).
z n = 1/M = a*D^b
The bed resistance is calculated as a function of the Water depth.
z n = 1/M = a*V^b
The bed resistance is calculated as a function of the velocity.
z
Table (Velocity, Resistance value)
A User defined table of resistance value as a function of actual velocity can be defined. The bed resistance value applied in the simulation will be the interpolated value from this table, depending on the actual velocity.
Note. To define the first line in the table, click the ‘Velocity’ bar in the
upper half of the page. Thereafter, press the <TAB> button and a new line will be present in the grid in the upper part of the page.
All features (equations and table) can be defined both globally and locally.
If a Triple Zone Approach is applied, it can be specified for which zones the bed resistance is to be determined from the toolbox definitions and for which zones the bed resistance number should be taken from the standard
Bed Resistance page. Activate the ‘Apply to Sub-sections’ check-boxes to specify that for a specific zone the bed resistance values must be determined from the toolbox definitions.
If one of the equations has been applied, the user must define values for the coefficient, a, and exponent, b. Additionally, a minimum and a maximum value must be specified to control, that bed resistance values calculated from the equations are inside the interval considered reasonable by the user for the specific setup.
Please note: Using a Chezy or Manning Resistance Formula (defined in the Bed Resistance page) the maximum bed resistance requires the smallest value of Manning’s M or Chezy’s C. Similar, the minimum bed resistance corresponds to the highest value of resistance numbers M or C.
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6.9
Wave Approx
Figure 6.10
The Wave Approximation property page.
There are four possible flow description available in MIKE 11. The flow descriptions can be selected globally for the system and/or locally for individual branches. Locally specified flow descriptions must be specified for the whole branch.
In general it is recommended to use the ‘fully dynamic’ or the ‘high order fully dynamic’ flow descriptions. Only in cases where it can be clearly shown that the ‘diffusive wave’ or the ‘kinematic wave’ are adequate should they be used. The latter two flow descriptions are simplifications of the full dynamic equations. These are provided to improve the computational efficiency of models in specific circumstances. They should only be used when the simplifications/assumptions upon which they are based are valid (see below).
6.9.1
Fully Dynamic and High Order Fully Dynamic
The ‘fully dynamic’ and ‘high order fully dynamic’ flow description should be used where the inertia of the water body over time and space is important. This is the case for all tidal flow situations and in river systems where the water surface slope, the bed slope and the bed resistance forces are small.
The ‘high order fully dynamic’ flow description contains specific high order and upstream centred friction terms in the momentum equation. This
308 MIKE 11
Default values modification allows simulations to be performed at longer time steps than the ‘fully dynamic’ description.
6.9.2
Diffusive Wave
The diffusive wave description is a simplification of the full dynamic solution and assumes that there are no inertial forces (i.e. the inertial terms are dropped from the momentum equation). It is suitable for backwater analysis slow propagating flood waves and for cases where the bed resistance forces dominates. It is not suitable for tidal flows.
6.9.3
Kinematic Wave
The kinematic wave approach assumes a balance between the friction and gravity forces on the flow. The description is suitable for relatively steep rivers without backwater effects.
6.10 Default values
Hydrodynamic Editor
Figure 6.11
The Default Values property page.
The default value property page contains various parameters related to the computational scheme. These parameters are essential for the simulation and have been given default values. The parameters can be modified if required. The following brief descriptions are provided (see also section
Coefficients, HD default parameters in the Reference Manual).
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Hydrodynamic Editor
6.10.1 Computation Scheme
Delta
The time-centring of the gravity term in the momentum equation.
Delhs
The minimum allowable water level difference across a weir. To obtain a steady solution for differences below this limit a linear flow description is used.
Delh
The Delh factor controls the dimensions of an artificial ‘slot’, which is introduced to a cross section to prevent ‘drying out’ of the section. The artificial slot is a small void introduced at the base of the section and allows a small volume of water to remain in the section preventing computational instabilities at low flows. The slot is inserted at height Delh above the river bottom and extends to a depth of 5 .
Delh below this level.
Alpha
The velocity distribution coefficient used in the convective acceleration term of the momentum equation.
Theta
A weighting factor used in the quadratic part of the convective acceleration term of the momentum equation.
Eps
The water surface slope used in the diffusive wave approximation. If the water surface slope becomes greater than EPS, the computational scheme will become fully forwarded upstream. The parameter can be used to control the stability of the computation.
Dh node
Not used
Zeta min
The minimum head loss coefficient allowed in the computation of flow over structures.
Struc Fac
Not used
310 MIKE 11
User Def. Marks
Max Iter (Inter1Max)
The maximum number of iterations permitted at each time step to obtain a solution at a structure.
Number of Iter (NoIter)
The number of iterations at each time step, generally 0, 1 or 2.
Max Iter Steady
The maximum number of iterations used to obtain a steady state water level profile at the start of a simulation. Only used when the initial conditions for the simulation are either ‘steady’ or ‘steady + parameter’. If the simulation type is ‘Quasi steady’ then the parameter is used at each time step.
Froude Max and Froude Exp
‘Froude Max’ is the parameter ‘a’ in the enhanced formulation of the suppression term applied to the convective acceleration term in the momentum equation. Similarly ‘Froude Exp’ is the parameter ‘b’ in the enhanced formulation. By default the values are -1, indicating that the traditional formulation is used. For situations with high Froude numbers combined with small grid spacing the enhanced formulation can be applied, see section Suppression of convective acceleration term in the Reference Manual.
6.10.2 Switches
Node Compatibility
This switch should be set to water level since the energy compatibility has not yet been implemented.
6.11
User Def. Marks
The User Defined Markers page offers a possibility for the user to define special markers/points in the river network by defining the location and the top level of the item. Items defined as user defined markers can be presented on a longitudinal profile in the result presentation programme;
MIKEView. Markers could be the location of an important hydraulic structure, a gauging station or other significant items in the modelling area.
Note. To define the first Marker in an empty page, click the ‘Mark title’
bar in the upper half of the page. Thereafter, press the <TAB> button and a new line will be present in the grid in the upper part of the page as well as
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311
Hydrodynamic Editor a new column is introduced in the ‘location grid’ in the lower half of the page. Write the name of the marker in the empty line in the upper grid, and this name will automatically be transferred as the name of the column.
Markers can be defined as single points only and as markers defined along a river stretch. The ’Interpolate’ column must be checked in case a linear interpolation is requested on stretches between chainages and marker levels defined in this page. In case a user defined mark should be presented on the longitudinal profile as a single point (e.g. a bridge location or flood mark indicator) the Interpolate check-box must be un-checked.
6.11.1
Activation of Bed resistance Triple Zone Approach
The Bed resistance Triple Zone approach is activated by defining two markers with the names; ‘ZONE1-2’ and ‘ZONE2-3’. Marker names can not differ from these names if they are to be used for defining zone-separators for the triple zone approach.
After defining the marker names, the zone-separator levels must be defined as two levels defined in stations along the river stretches in the setup where the separation between Zone 1 and 2, and Zone 2 and 3 are present. That is, a longitudinal profile/line should be defined for each of the two zone-separators.
Please Note: In case the Triple Zone Approach has been activated and
zone separator lines are not defined for the entire setup, MIKE 11 uses the uniform bed resistance values in the points where separator lines are not defined. The resistance value used at these points is the value (global or local) defined for the lower zone.
Figure 6.12shows an example where a single point marker has been
defined (‘Main Bridge’ at RIVER1, chainage 1500) and triple zone separator lines has been defined in RIVER1 in the reach from chainage 0.0 to
5000.
312 MIKE 11
Encroachment
Figure 6.12
Example of defining User Defined Marks
6.12 Encroachment
Encroachment simulations are setup through this page. An encroachment simulation consist of two or more simulations. The first simulation acts as a reference simulation to which all other results are compared. The reference simulation is set up as any ordinary steady state simulation.
Based on the reference simulation a number of encroachment simulation may be carried out. Each of these are specified as a line in the Encroachment simulation overview. Hereby one can evaluate different encroachment strategies through the same setup. The parameters used for defining the encroachment simulations are described below.
Note that only MIKE 11’s default steady state solver may be used. Further
since the encroachment module utilizes the steady state solver, the installation of MIKE 11 should include a steady state module to make the encroachment module function.
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Figure 6.13
The encroachment property page.
6.12.1 Iteration
Max no. of iterations
The maximum number of iterations allowed when obtaining encroachment positions. The default setting is 20. If a non-valid number (<2) is entered the code will use the value to 2. Note that this parameter is global for all encroachment simulations and stations.
6.12.2 Location
The location of the encroachment station is entered here through a river name and a chainage. If a location is entered for which no corresponding cross section exists a warning is issued at run time and the station will be ignored in the subsequent simulation.
6.12.3 Encroachment method
Method
A total of five different methods are available:
314 MIKE 11
Encroachment
1 Fixed position: The position of the encroachment stations are user specified.
2 Fixed width: The position of the encroachment stations are found through a user defined width.
3 Conveyance reduction: The encroachment stations are found through user specified conveyance reductions.
4 Target water level: The position of the encroachment stations are determined by ensuring that the conveyance of the encroached cross section at the user defined target water level is equal to the conveyance of the undisturbed cross section at the reference water level.
5 Iteration: The encroachment positions are found through an iterative procedure where steady state simulations are evaluated. The objective of the evaluations are to reach a user defined target water level or energy level.
Sides
It is possible for the encroachment to take place on both sides of the main channel or only on one of the sides. For this purpose the sides combo box may be used.
Note: If the method chosen for encroachment is ’Fixed width’ then the
sides switch is automatically set to both sides. Since a fixed width encroachment only makes sense if both sides are to be encroached.
6.12.4 Encroachment positions
Left and right offset
The user may specify a left and a right offset for the encroachment positions. These specify the minimum distance between the position of the encroachment and the river bank. The latter being defined by markers 8 and 9.
Left and Right position (only encroachment method 1)
For the fixed position encroachment method the user should here specify the position of the left and the right position as the distance from the river bank.
Width (only encroachment method 2)
The width used for the fixed encroachment width method is entered here.
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6.12.5 Reduction parameters (only encroachment methods 3 to 5)
Reduction type
The way that the conveyance reduction should be accomplished is specified here. Three possibilities are available:
– Equal: The conveyance reduction is accomplished by reducing the conveyance equally on both flood plains.
– Relative: The conveyance reduction is accomplished by reducing the conveyance relative to the conveyance distribution in the reference simulation.
– Specified: The user may specify the conveyance reduction for each of the flood plains.
The above settings are only meaningful if the sides switch is set to ’both sides’. If the latter is not the case the reduction type switch should be set to specified.
Left and Right reduction
These are only used if the reduction type is set to ’specified’. The conveyance reduction is entered in percentage of the total conveyance.
Total reduction
If the reduction type is set to either ’Equal’ or ’Relative’ this field becomes active. The total required conveyance reduction is entered here in percentage.
6.12.6 Target Values
These fields are only of importance if the encroachment method is chosen as either 4 or 5. In method 4 a water level target is used to determine the encroachment. In method 5 the simulation tries to determine the encroachment stations such that the water level or the energy level found through simulation is equal to the target water level or energy level respectively.
Water level change
The target water level used in the simulation is the reference water level plus the user specified water level change.
Energy level change (only encroachment method 5)
The target energy level used in the simulation is the reference energy level plus the energy level change.
316 MIKE 11
Encroachment
Encroachment strategies using method 5
If method 5 is utilised there are three possible strategies.
Water level target: The encroachment may be carried out so that only
a water level target is considered. This strategy is achieved by setting the water level change to a non-zero value and the energy level change to zero.
Energy level target: The encroachment is carried out so that only an
energy level target is considered. This strategy is achieved by setting the water level change to zero and the energy level change to a nonzero value.
Water level target and energy level target: The encroachment is car-
ried out so that a water level target is met. Once this has been achieved the energy level is checked. If the energy level is above the energy level target the code will reconsider the encroachment and try to satisfy the energy level request instead. This strategy is achieved by setting both the water level change and the energy level change to non-zero values.
Please note that the position of the encroachments are found through an iterative procedure. This procedure considers each cross section individually starting downstream and working upstream. To ensure that this method is successful do not use method 5 for river reaches which form part of a loop in a network. Further method 5 is designed for encroaching river reaches where the discharge distribution can be determined a priori, thus the method will be less successful for networks having river bifurcations in a downstream direction as opposed to bifurcations in upstream directions. Finally it should be mentioned that not all user specified targets can be reached. If this is the case the code will issue a warning and return the encroachment which is closest to the requested target.
6.12.7 Encroachment simulation overview
Each row in this overview represents an encroachment simulation. The parameters set here are used as default values for all the stations entered
subsequently in the Encroachment station overview. Thus the number of
rows is equal to the number of encroachment simulations which are to be carried out.
6.12.8 Encroachment station overview
Each row in this overview represents a location along a river reach. For each location all of the above parameters may be set individually (except max no. of iterations).
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Hydrodynamic Editor
6.12.9 General guide lines for carrying out encroachment simulations
Since MIKE 11 uses preprocessed data for the simulation it is important to have a fine resolution in the cross sectional processed data. Further the encroachment module only allows equidistant level selection for the cross sections used for encroachment. If the latter is not the case an error message will be displayed and the simulation stopped.
For encroachment simulations only the initial start time in the simulation editor is used. This start time is used for determining the boundary values in the river set-up. Note that constant boundary conditions in MIKE 11 are specified by the use of non-varying boundary conditions in the boundary editor.
The choice of encroachment method depends on the application. Please note that methods 1 to 4 all analyse the individual cross section without considering the rest of the network. For instance method 4 seeks a water level change with the same conveyance as the reference level and thus only considers the individual cross section from a point of view of flow taking place at the natural depth. The actual steady state simulation carried out may not give rise to the required water level change. To obtain the latter method 5 should instead be used.
6.13 Mixing Coefficients
318
Figure 6.14
The Mixing Coefficients property page.
MIKE 11
Mixing Coefficients
Used only in conjunction with the quasi two dimensional steady state vegetation module. This menu is used for setting the mixing coefficients between adjacent panels in the river cross sections. Both global and local values may be set here.
Local values are shown at the bottom in table form.
6.13.1 Water & Water
HWC & LWC
In this box the mixing coefficients between the low water channel (LWC) and the high water channel (HWC) are set. The data is entered as a function of the ratio between the width of the low flow channel and the total width of the river (b/B). Linear interpolation is used to obtain intermediate values.
Important! The table should start with b/B=0 and end with b/B=1 and all
intermediate values of b/B must be monotonically increasing. If the table does not meet this criteria a warning is issued and the default settings are used.
Note. To define the first line in the table, click the ‘b/B’ bar in the upper
half of the page. Thereafter, press the <TAB> button and a new line will be present in the grid in the upper part of the page.
Independent Veg. Zones f
The mixing coefficients at a water/water boundary at an independent vegetation panel and a normal panel.
Expansion/Contraction f
The mixing coefficients at a water/water boundary at a dead water interface.
6.13.2 Location
The river name and location (chainage) is displayed here.
6.13.3 Water & Vegetation
The mixing coefficients at water/vegetation boundaries are set here.
Independent Vegetation Zones
Mixing coefficient at independent vegetation zones.
Vegetation Zones adjacent to levee
Mixing coefficient at vegetation zones adjacent to levee.
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Hydrodynamic Editor
6.14 W. L. Incr.- Curve
Used only in conjunction with the Quasi Two Dimensional Steady State vegetation module. This menu is used for setting the parameters which are used for determining the increment of the water level due to the presence of river curvature.
The tab is illustrated in Figure 6.15 with all the different features all of
which are described below.
Figure 6.15
Water level increment due to curves.
6.14.1 General
Enabling water level increment due to curves
If the effect of the river curvature on the water level is to be included in the calculations this box should ticked.
Load Branch and Chainage button
This button activates a window with three choices z
Load the Branch and Chainage from Cross Section editor.
320 MIKE 11
W. L. Incr.- Curve z z
Load the Branch, Chainage and Radius from Cross Section editor and
Network Editor.
Load the Branch, Chainage, Radius and Channel Width from Cross
Section editor and Network Editor.
Tick the appropriate choice and click OK.
Important! To successfully activate the second or third choice (Radius /
Radius and Width) it is required that the network file is open. If the
NWK11 file is not open, then go to the Simulation Editor (Input page) and press the ’Edit...’ button to open the network-file. Thereafter, it is possible to extract the Radius and/or Width values.
At the bottom of the editor a table is displayed with river name, chainage and the four parameters appropriate for the determination of the water level increment. The parameters which are not greyed may be edited.
6.14.2 System Definition
In this box the user may tick the appropriate parameters which should be user defined or system defined. The parameters which are subsequently used in the calculations are:
1 Average Range.
2 Curvature Radius.
3 Water Surface Width.
4 Velocity.
Note! If either 2 or 3 is ticked the velocity is also automatically ticked.
6.14.3 Tabular view
The editor displays a tabular view of the parameters which will be used in the determination of the water level increment. The user should edit these values appropriately.
In the column "Average Range" the user can control the calculation of the curvature radius. If the average range is set to "None" no water level increment due to curvature applies. For other values of average range a curvature radius is initially calculated or assigned (depending on the what's selected in the group box "System Definition") individually in each hpoint. If the average range equals "Single" the curvature radius is kept unchanged, otherwise this is averaged over a number of h-points. Consecutive h-points with the same average range setting is lumped together when calculating an average curvature radius. "Multiple 1/2" is used for h-
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321
Hydrodynamic Editor points to be included in both the upstream and downstream averaging reach.
6.15 Maps
MIKE 11 may be used to produce two dimensional maps based on the one-dimensional simulations. The maps are constructed through interpolation in space of the grid point results. Thus the maps constructed in this way should be viewed as a two dimensional interpretation of results from a one -dimensional model.
Various results may be mapped. The complete list consisting of z z z z water level water depth velocity velocity times depth z advection dispersion component
The maps may be of three types
1 minimum values
2 maximum values
3 dynamic
Only dynamic maps require a time span to be specified.
Through the mapping dialog the user specifies the area that is to be mapped, the type of map to be produced and the desired result item.
Depending on the user selections additional information may be required such as the advection dispersion component, the time span for which the map is to be produced and the storing frequency.
DEM Input Data options: The flood maps can be generated using cross section information only. However, if a DEM is available this can used for interpolating a more detailed depth map between cross sections and in additional flooded areas not located within the extend of the cross sections. The latter requires a help grid file to be created. This can easily be done using MIKE 11 GIS where additional storage areas are digitized as polygons and linked to a cross section, but the help grid file can also be created manually within MIKE Zero. Each cell in the help grid file must be an integer code referring to a cross section with an ID having the same
322 MIKE 11
Maps interger value (the first continious sequence of the characters 0-9 in the cross section ID is used as interger value of cross section ID). All cells within the same additional storage area will have the same code as they are to be mapped using the water level from the same cross section. Cells not be be mapped as additional storage areas should be zero, negative or
blank (delete value). Figure 6.17 shows an example of a flood map.
Hydrodynamic Editor
Figure 6.16
Flood map interpolated by MIKE 11 using a DEM between cross sections. The upper-right flood area not located within the extend of cross sections is mapped selecting the option “Map additional flooded area using help grid from MIKE 11 GIS”
Additionally the mapping interface may also be used to generate a digital elevation model (DEM) for the river bed. This is done by selecting the
DEM option. The DEM option only requires information for the area to be used. This option may further be used for introducing surveyed cross sec-
tions into a DEM covering the surrounding area. Figure 6.17 shows an
example of a DEM generated using the map capabilities of MIKE 11. The
DEM consists of the coarse background DEM (input topography) which has been superimposed with the topography found through interpolation
323
Hydrodynamic Editor of the cross sections in the MIKE 11 set-up. Please refer to the documentation of the bathymetry editor on how to generate a dfs2 bathymetry file.
Figure 6.17
An example of generating a DEM using MIKE 11. The DEM is constructed based on a background DEM in the form of a dfs2 file and surveyed cross sections found in the MIKE 11 set-up. To visualize the DEM MIKE Animator has been used.
6.15.1 A step by step guide to generating two-dimensional maps
1 Mark the ‘Generate map’ tick box
2 Locate the area where the map is to be produced. The area is given by the origo, the orientation, the cell size and the number of cells in the
two directions (see Figure 6.18).
3 Select the cell size to be used. Remember the finer the resolution the larger the result file.
4 Specify a name for the output file including the extension dfs2. Note that the browse button may be used to select the directory in which the file is to saved.
5 Open the network file to rectify that the map outline is correct.
324 MIKE 11
Maps
Figure 6.18
Definition of grid used for mapping. The rotation angle is positive clockwise. The definition of origo is also shown. The two blue lines indicate the location of the river system.
Hydrodynamic Editor
Figure 6.19
Overview of the location of the map in the network file. Note that the map is rotated with respect to the working area coordinates.
6 Select the item to be mapped. Note that if an advection dispersion component is to be mapped then the component number also needs to supplied.
7 Specify the type of map which is to be generated (minimum, maximum or dynamic).
8 If a dynamic map has been selected then the storing frequency and the mapping period need to be specified. Note that as an alternative the full
325
326
Hydrodynamic Editor simulation period may be used. The latter is achieved by activating the tick-box ‘default period’.
9 The storing frequency is a multiplier of the storing frequency specified in the simulation editor. Thus the mapping storing frequency is found as the general simulation editor storing frequency times the storing frequency specified in this menu.
10 If you have one or more additional digital elevation models in the form of a dfs2 files that you wish to include then continue to the next step otherwise go to step 16.
11 Please refer to the documentation of the bathymetry editor on how to generate a dfs2 bathymetry file.
12 The topographical information from the cross sections may be augmented or overridden with additional topographical information located in one or more dfs2 files. The dfs2 files need to be in a ‘NON-
UTM’ projection and contain an item describing the elevation. If the projection is different from ‘NON-UTM’ then simply open the dfs2 file in MIKE Zero and change the projection through the menu ‘edit -> geographical information...’. You may choose to save the file under a different name to retain the original data.
13 To activate the use of the an input topography use the ‘Apply DEM data between cross sections’ tick box.
14 Browse for the file(s) containing the additional topography and set the item number of the elevation.
15 If there are multiple background topography files then the ranking order needs to be specified. The lowest order number is given the highest priority.
16 Run the simulation.
17 The output files may now be viewed using the Result Viewer or MIKE
View. MIKE Animator if installed may also be used to view the results.
MIKE 11
Maps
Figure 6.20
An example of a flood inundation map presented in the Result
Viewer.
6.15.2 A step by step guide to generating Digital Elevation Models (DEM)
2 Select the map item as DEM
3 Please refer to the documentation of the bathymetry editor on how to generate a dfs2 bathymetry file.
4 The topographical information from the cross sections may be augmented or overridden with additional topographical information located in one or more dfs2 files. The dfs2 files need to be in a ‘NON-
UTM’ projection and contain an item describing the elevation. If the projection is different from ‘NON-UTM’ then simply open the dfs2 file in MIKE Zero and change the projection through the menu ‘edit -> geographical information...’. You may choose to save the file under a different name to retain the original data.
5 Do not select the ‘Apply DEM data between cross sections’ tick box.
6 Browse for the file(s) containing the additional topography and set the item number of the elevation. Please refer to the documentation for the bathymetry editor on how to generate a dfs2 bathymetry file.
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327
Hydrodynamic Editor
7 If there are multiple background topography files then the ranking order needs to be specified. The lowest order number is given the highest priority.
8 Run the simulation.
9 The output DEM may now be viewed using the Result Viewer or the grid editor. If installed MIKE Animator may also be used to view the generated DEM.
6.16 Groundwater Leakage
As a simplified alternative to using the fully dynamic link between MIKE
11 and MIKE SHE the groundwater leakage feature can be used. Here a predefined ground water level together with a leakage coefficient is used to calculate an exchange a water loss from or water gain to the river. The loss or gain is calculated using the specified leakage coefficient and the difference between the predefined ground water level and calculated water level in the river.
The predefined ground water level is defined as a global boundary in the boundary editor.
6.17 W. L. Incr.- Sand Bars
Used only in conjunction with the Quasi Two Dimensional Steady State vegetation module. This menu is used for setting the parameters which are used for determining the increment of the water level due to the presence of sand bars.
The tab is illustrated in Figure 6.21 with all the different features all of
which are described below.
328 MIKE 11
W. L. Incr.- Sand Bars
Figure 6.21
Water level increment due to sand bars.
6.17.1 General
Enabling water level increment due sand bars
If the effect of sandbars on the water level is to be included in the calculations this box should be ticked.
Load Branch and Chainage button
This button loads the branch name and chainage from the cross section editor (remember to have the simulation editor open).
At the bottom of the editor a table is displayed with river name, chainage and parameters appropriate for the determination of the water level increment.
6.17.2 System Definition
In this box the user may tick the appropriate parameters which should be user defined or system defined. The parameters which are subsequently used in the calculations are either z
Bed slope, low water channel width and water area of annual maximum discharge or
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329
Hydrodynamic Editor z
An observed water level increment.
6.17.3 Tabular view
The editor displays a tabular view of the parameters which will be used in the determination of the water level increment. The user should edit these values appropriately.
6.18 Heat Balance
The property page used for setting up heat exchange simulations is illus-
330
Figure 6.22
The heat balance property page.
The information needed for the heat exchange calculation are (information is also needed in the boundary-editor):
Latitude (N pos.)
Latitude of the considered area. Used in solar radiation calculation.
MIKE 11
Heat Balance
Longitude (W pos.)
Longitude of the considered area.
Time meridian zone (W pos.)
The standard longitude for the time zone.
Displacement in time
Summertime correction: +1hour if the clock is 1hour ahead.
Light attenuation
Attenuation of solar radiation in the water column. Used to distribute the incoming solar radiation over the different layers.
Constant in Beer's law
The incoming solar radiation is distributed over the layers by use of the following formula:
I
I tot
(
–
β where I
sun
is the solar radiation,
β is constant in Beer's law, (D-z) is distance from surface and a is light absorption.
Radiation Parameter A
Daily radiation under cloudy skies is determined by:
(6.4)
0
d
where n is sunshine hours and N is the day length.
Radiation Parameter B
See above.
Vaporization Parameter A
Vaporative heat loss is determined by:
LC e
+
2
(
W
Q a
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331
Hydrodynamic Editor where L is latent heat of vaporization, C
e
the wind speed 2 m above surface, Q
w
face, and Q
a
is the moisture coefficient, W
2
is
is the vapor density close to the sur-
is the vapor density close to the surface.
Vaporization Parameter B
See above.
6.19 Stratification
The property page used for setting up stratified flow simulations is illus-
332
Figure 6.23
The stratification property page.
Note that if stratified flow is to be simulated then the specific branch must be defined as being stratified.
The information needed for the stratified branches are:
MIKE 11
Stratification
No. of layers
Number of layers in the stratified branches. The same number of layers is assumed in all stratified branches. The thickness of a layer is equal to the local depth divided by the number of layers.
Density calculated
Tick means yes and no tick means no. If densities are calculated it is done on the basis of the simulated water temperatures, and if not density is assumed to be 1000 kg/m3.
Turbulence model
Viscosity
In the case one chose a constant viscosity under turbulence model it is the used viscosity in the calculations.
Turbulence model in fluid
It is possible to chose between constant viscosity, mixing-length, k-model and k-
ε turbulence models. It is recommended to use the k-ε model.
Turbulence model at bed
Presently only drag coefficient can be chosen. The Chezy or Manning number specified is used to calculate the bed friction, see scientific documentation.
Richardson number correction
Tick means yes and no tick means no. If Richardson numbers correction is active the turbulence is dampened in stable stratified areas.
Corrections (reductions)
Baroclinic pressure: Factor
A factor multiplied on the baroclinic pressure. Default is 1, whereby the correct equation is solved. If the factor is 0 the baroclinic pressure term is removed in the momentum equation.
Baroclinic pressure: Local bed slope
The higher the number the less the baroclinic pressure term is taken into account in areas with steep bed gradients.
Hydrodynamic Editor
333
Hydrodynamic Editor
Convection /Advection: Factor horizontal momentum
A factor multiplied on the horizontal exchange of horizontal momentum
(uu). Default is 1, whereby the correct equation is solved. If the factor is 0 the term is removed in the momentum equation.
Convection /Advection: Factor vertical momentum
A factor multiplied on the vertical exchange of horizontal momentum
(uw). Default is 1, whereby the correct equation is solved. If the factor is 0 the term is removed in the momentum equation.
Convection /Advection: Factor advection
A factor multiplied on the advection terms in the transport equation.
Default is 1, whereby the correct transport equation is solved. If the factor is 0 the advection of matter is removed in the transport equation.
Dispersion: Factor horizontal viscosity
A factor multiplied on the turbulent viscosity to get the horizontal diffusion in the transport equation.
Dispersion: Factor vertical viscosity
A factor multiplied on the turbulent viscosity to get the vertical diffusion in the transport equation.
6.20 Time Series Output
On this property page request is made for time series output files to be generated during the simulation. This output is in addition to the regular and the additional .res11 output file. Time series output can be saved in
.dfs0 or ASCII files. Time series output files are typically requested in stead of manually extracting time series data in selected grid points from the .res11 file after the simulation has been completed. This is often useful for automatic or manual calibration or when running production simulations. The time series output page is shown in the following figure:
334 MIKE 11
Time Series Output
Figure 6.24
Time series output property page in HD parameter editor
6.20.1 Generating Time Series Output Files
Selecting this option, the time series output files will be generated during the simulation. For each row in the grid control one time series output file will be generated. The format column gives three choices for the file format: z z z
Dfs Timeseries Bridge: This will generate a .dfs0 file in the standard
DHI file format for time series. Files can be loaded into for instance the time series editor, plot composer, MIKE View or used as simulated data for the auto calibration tool.
ASCII format 1 Timeseries Bridge. This will generate an ASCII file with a column based format. There will be one time column and one column for grid point item selected for output. The number of lines will equal the number of saved time steps.
ASCII format 2 Timeseries Bridge. This will generate an ASCII file with a table based format. There will be one table for each time step saved. Each table will have rows corresponding to the number of selected grid points, and columns corresponding to the number of selected items.
Hydrodynamic Editor
335
Hydrodynamic Editor
6.20.2 Text File Settings
These check boxes only apply for the two ASCII file formats. z z z z z z
Minimum: A separate table at the bottom of the file will show the minimum value of the output items.
Maximum: A separate table at the bottom of the file will show the maximum value of the output items.
Time of minimum: A separate table at the bottom of the file will show the time of minimum value of the output items.
Time of maximum: A separate table at the bottom of the file will show the time of maximum value of the output items.
Delimiter in output file: Between each column a special character like semicolon, comma etc can be requested. This makes import to for instance Excel easier.
Width of columns: The desired minimum width of each column can be specified.
6.20.3 Time Period in Output
Selected, this check box makes it possible to define the period for which the time series output is generated. If not selected, the full simulation period will apply. The saving frequency is always equal to the saving frequency for the regular .res11 output file as specified in the simulation editor.
6.20.4 Items in Output
Time series output is produced for the selected items of which some are dynamic and some are static. Dynamic items are items between "Water level" and "Bed shear stress". In the dfs0 files only dynamic items will be saved. In ASCII items both dynamic and static items will be saved.
A user defined name for the item can be specified. If not specified, the default name will apply.
The number of decimals will only apply for output in ASCII files.
6.20.5 Grid Points in Output
The grid points from which the time series output is to be generated are specified here. Using the radio button to the right, the user may choose to generate time series output from all, selected or all-but-selected grid points. The selection of grid points is done through specifying a number of reaches (river name, upstream chainage and down stream chainage). Sin-
336 MIKE 11
Time Series Output gle grid points can be selected by setting the upstream chainage equal to the downstream chainage.
Time series output is only generated from h-points.
Hydrodynamic Editor
337
Hydrodynamic Editor
338 MIKE 11
A D V E C T I O N - D I S P E R S I O N E D I T O R
339
340 MIKE 11
7 ADVECTION-DISPERSION EDITOR
The AD Editor is used in conjunction with the following modules: z z z z
Advection Dispersion module (pure AD)
Water Quality module
Cohesive sediment transport module
Advanced cohesive sediment transport module
A brief description of each of these modules is provided below.
7.0.1
Advection-Dispersion module (AD)
The advection-dispersion (AD) module is based on the one-dimensional equation of conservation of mass of a dissolved or suspended material, i.e. the advection-dispersion equation. The module requires output from the hydrodynamic module, in time and space, in terms of discharge and water level, cross-sectional area and hydraulic radius.
The Advection-Dispersion Equation (p. 342) is solved numerically using
an implicit finite difference scheme which, in principle, is unconditionally stable and has negligible numerical dispersion. A correction term has been introduced in order to reduce the third order truncation error. This correction term makes it possible to simulate advection-dispersion of concentration profiles with very steep fronts.
7.0.2
Water Quality module (WQ)
The water quality (WQ) module deals with the basic aspects of river water quality in areas influenced by human activities: e.g. oxygen depletion and ammonia levels as a result of organic/nutrient loadings. The WQ-module is coupled to the AD module, which means that the WQ module deals with the chemical/biological transforming processes of compounds in the river and the AD module is used to simulate the simultaneous transport process. The WQ module solves a system of coupled differential equations describing the physical, chemical and biological interactions in the river. The relevant water quality components must be defined in the AD editor.
7.0.3
Cohesive Sediment Transport module (CST)
The cohesive sediment transport (CST) module also forms part of the AD module. In contrast to the non-cohesive sediment transport (NST) module, the sediment transport cannot be described by local parameters only because the settling velocity of the fine sediments is very low. The cohesive module uses the AD module to describe the transport of the sus-
Advection-Dispersion Editor
341
Advection-Dispersion Editor pended sediment. Erosion/deposition is modelled as a source/sink term in the advection-dispersion equation. The erosion rate depends on the local hydraulic conditions whereas the deposition rate depends on the concentration of the suspended sediment and on the hydraulic conditions.
The module can also be used when resuspension of sediment affects water quality. This is because the resuspension of cohesive sediment often gives rise to oxygen depletion due to the high organic content and associated oxygen demand (COD) in the cohesive sediment. Likewise resuspension of cohesive sediment can give rise to heavy metal pollution since heavy metals adhere to the sediment.
7.0.4
Advanced Cohesive Sediment Transport module (A CST)
The Advanced cohesive sediment transport module provides an alternative, more complex, process description than the simple CST module. This module is especially useful in situations where a mass balance of cohesive sediment is required in order to simulate the accumulation of sediment.
Then, knowing the exact location of sediment pools, it is possible to estimate the siltation in navigation channels, waterways, harbours etc.
The advanced cohesive sediment transport module is part of the advection-dispersion (AD) module. As for the standard formulation, the sediment transport is described in the AD-model through the transport of suspended solids. Erosion and deposition of cohesive sediment is represented in the AD-model as a source/sink term. Whereas the erosion rate depends only on local hydraulic conditions (bed shear stress), the deposition rate also depends on the suspended sediment concentration.
7.0.5
The Advection-Dispersion Equation
The one-dimensional (vertically and laterally integrated) equation for the conservation of mass of a substance in a solution, i.e. the one-dimensional advection-dispersion equation reads:
∂t
+
∂x
–
∂x
-------
= –
AKC
+
C
2
q
where
C
: concentration
D
: dispersion coefficient
A
: cross-sectional area
(7.1)
342 MIKE 11
K
: linear decay coefficient
C
2
q
: source/sink concentration
: lateral inflow
t x
: space coordinate
: time coordinate
The equation reflects two transport mechanisms: z
Advective (or convective) transport with the mean flow; z
Dispersive transport due to concentrations gradients.
The main assumptions underlying the advection-dispersion equation are: z z z
The considered substance is completely mixed over the cross-section, implying that a source/sink term is considered to mix instantaneously over the cross-section.
The substance is conservative or subject to a first order reaction (linear decay)
Fick's diffusion law applies, i.e. the dispersive transport is proportional to the concentration gradient.
To operate the AD-module a number of dialogs are available all of which are described in the following.
Advection-Dispersion Editor
343
7.1
Sediment layers
Advection-Dispersion Editor
344
Location
Figure 7.1
The Sediment Layers property page.
Initial conditions for the sediment layers are defined on the Sediment Layers page. Selection pop down menus are available for the component types
‘Single cohesive’, ‘Multi cohesive’ or ‘Non cohesive’.
Component
Three types can be selected: Single Layer Cohesive, Multi Layer Cohesive and Non-Cohesive.
Layers
Only available when Component is chosen as a Multi Layer Cohesive component. The user can select between Upper, Middle and Lower representing the three layers in the Multi Layer Cohesive model. Parameters must be specified for each of the layers.
Table
Only applicable for Multi Layer model components. Instead of giving the
MIKE 11
Sediment layers
Height
Although the header says 'Height' the initial data should be entered as volume of sediment per length of river. In order to convert this initial data into an amount MIKE 11 uses the porosity and the relative density speci-
fied in the Non-cohesive ST (p. 346) property page.
Density
The density of the layer.
Pot. fac.
Initial amount of BOD attached to the sediment. Only applicable for a Single Layer component.
Global
If this box is checked the entered parameters are used globally.
River Name
The name of the river for which the data applies.
Chainage
The chainage of the river for which the entered data applies.
Parameters
For multi layer components a volume width relation can be entered. The width in this relation is the width of the cross section, the volume is the volume of sediment per length of the river. It is hereby possible to vary the thickness of the sediment layer along the cross section.
7.1.1
Single layer cohesive component.
When the single layer model is used only one sediment layer is displayed.
The sediment layer initial conditions are defined by the following parameters:
Potency factor
Initial amount of BOD attached to the sediment (kg BOD / kg sediment).
Advection-Dispersion Editor
345
7.2
Non-cohesive ST
Advection-Dispersion Editor
346
Figure 7.2
The Non-Cohesive property page.
This page contains input parameters for Non-Cohesive components. A non-cohesive component is defined using the data section at the bottom of the page.
Model constants
Model Type
A pop down menu provides a choice from two types of sediment transport formulations; the Engelund-Fredsøe and the van Rijn model.
Fac.1
Calibration factor for bed load transport. The calculated bed load is multiplied by the calibration factor.
Fac.2
Calibration factor for suspended load transport. The calculated suspended load is multiplied by the calibration factor.
Beta
Dynamic friction factor used in the Engelund-Fredsøe model.
Typical range: 0.50 - 0.65.
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Ice model
Kin.visc.
The kinematic viscosity of water.
Porosity
The porosity of the sediment.
Rel.dens.
The relative density of the sediment.
Thetac
Shield’s critical parameter. Typical range: 0.04 - 0.06.
Data
Component
Here a Non-cohesive component is selected.
grain size
The D
50
value.
st dev.
Standard deviation in the grain size distribution.
Global
If this box is checked the entered parameters are used globally.
River Name
The name of the river for which the data applies.
Chainage
The chainage of the river for which the entered data applies.
7.3
Ice model
This property page contains parameter information for the MIKE 11 ice module. The following parameters must be specified: z z z
Active ice model
Constant cross section area
Latitude
Advection-Dispersion Editor
347
Advection-Dispersion Editor z z z z z z z
Latent heat
Specific heat of water
Density of water
Heat flux
Ice density
Air temperature
Wind speed z z z z
Cloudiness
Visibility
Cloud density
Precipitation z z
Ice thickness
Ice cover z
Ice quality
The latter three parameters can also be given local values in the grid control.
7.4
Additional output
The additional output page contains check boxes which can be used to store internal model parameters in result files with the extension (.RES11).
Mass
The mass in the system. Given in the units specified on the ‘Components’
property page. Total and total accumulated as well as grid and grid accumulated values can be selected.
348 MIKE 11
Additional output
Figure 7.3
The additional output property page.
Mass balance
The mass balance is given in o/oo (per thousands). Total and total accumulated as well as grid and grid accumulated values can be selected.
1. order decay
The 1st order decay is given in the units specified on the ‘Components’
property page, per second. Total and total accumulated as well as grid and grid accumulated values can be selected.
Mass in branches
Transport, total
The total transport is given in the unit specified on the ‘Components’
property page, per second. Grid and grid accumulated values can be selected.
Dispersive transport
The dispersive transport is given in the unit specified on the ‘Components’
property page per second. Grid and grid accumulated values can be selected.
Convective transport
be selected.
Advection-Dispersion Editor
349
Advection-Dispersion Editor
7.5
Components
Component names and numbers must be specified in this dialog.
The components can be user defined or selected using the predefined component sets provided with the water quality module. Each component is modelled using a defined concentration ‘unit’ and ‘type’.
350
Figure 7.4
The component property page.
WQ / Sediment interaction
If this check box is checked Mike11 will include the exchange of BOD between the water and the sediment. Both cohesive sediment and noncohesive sediment will be included. All together four components will be added to the component list:
– COHE: Cohesive sediment. Type must be ‘Single Layer Cohesive’.
– COHE BOD: BOD attached to cohesive sediment. Type must be
‘Normal’.
– NON_COHE: Non-cohesive sediment. Type must be ‘Non-Cohesive’.
– NON-COHE BOD: BOD attached to non-cohesive sediment. Type must be ‘Normal’.
Fill WQ components
By selecting the Fill WQ components button a number of predefined component sets for the water quality modules can be accessed.
MIKE 11
Components
Figure 7.5
Selecting different WQ model components.
A short description of the WQ model types is listed below.
– BOD/DO: Components used for the standard water quality (WQ) model. Up to 6 levels can be chosen using the levels option. Coliformal bacteria and phosphorus components can also be included.
– EU: Components used for the eutrophication module.
– EU extended: Components used for the extended eutrophication
(EU) module.
– HM: Components used for the heavy metal (HM) module.
– OCRE: Components used for the iron-oxidation (OCRE) module.
– NP_TRANS: Components used for the nutrient transport module.
– EQ SOLVE: Components used for the equation solver module.
Component
Here all components for AD and/or WQ simulations are defined.
Units
Here the unit of the component is specified.
– my-g/m
3
: Microgram per cubic meter.
– mg/m
3
: Milligram per cubic meter
– g/m
3
: Gram per cubic meter
– kg/m
3
: Kilogram per cubic meter
– my-g/l: Microgram per litre.
Advection-Dispersion Editor
351
Advection-Dispersion Editor
– mg/l: Milligram per litre.
– g/l: Gram per litre.
– Deg. Cel: Degrees in Celsius.
– Counts x 1E6/100 ml: Bacterial counts.
Type
– Normal: A component used for AD and/or WQ simulations.
– Single layer cohesive: A component used only in the single layer cohesive sediment transport model.
– Multi cohesive: A component used in the multi layer cohesive sediment transport model.
– Non-cohesive: Used only if WQ/Sediment interaction is chosen,
see WQ / Sediment interaction (p. 350). Note that this non-cohesive
sediment model can not be used for morphological simulations. It is only used to simulate the exchange between the water and the sediment of BOD attached to the sediment.
7.6
Dispersion
The dispersion coefficient, D, is described as a function of the mean flow velocity, V, as shown below.
D
=
aV b
(7.2)
Where a is the dispersion factor and b the dispersion exponent. Typical value ranges for D: 1-5 m 2 /s (for small streams), 5-20 m 2 /s (for rivers).
Both the ‘dispersion factor’ and the ‘dispersion exponent’ can be specified. If the dispersion exponent is zero then the dispersion coefficient D becomes constant (equal to the dispersion factor). By default the dispersion is zero (i.e. there is only advective transport and no dispersion). The
‘Minimum dispersion coefficient’ and the ‘Maximum dispersion coefficient’ parameters are used to control the range of the calculated dispersion coefficients.
352 MIKE 11
Dispersion
Figure 7.6
The dispersion property page.
Global values
The dispersion can be defined for the whole setup at once by entering data in the Global Values section.
Dispersion factor
Here the dispersion factor is entered. This corresponds to a in (7.2).
Exponent
Here the dispersion exponent b from (7.2) is entered.
Minimum disp coeff.
When using (7.2) to calculate the dispersion coefficient it is depending on
the velocity that will vary during the simulation. To limit the interval in which the dispersion coefficient will vary the lowest allowable value of the dispersion coefficient can be entered here.
Maximum disp coeff.
When using (7.2) to calculate the dispersion coefficient it is depending on
the velocity that will vary during the simulation. To limit the interval in which the dispersion coefficient will vary the highest allowable value of the dispersion coefficient can be entered here.
Local Values
Mike11 will use the values specified under global values except for those places were local values have been specified.
Advection-Dispersion Editor
353
Advection-Dispersion Editor
River Name
Name of the river with local dispersion values.
Chainage
Chainage in river with local dispersion values
Dispersion factor
Local value of the dispersion factor
Exponent
Local value of the dispersion exponent
Minimum disp coeff.
Local value of the minimum dispersion coefficient.
Maximum disp coeff.
Maximum value of the dispersion coefficient
Example
In Figure 7.6 both global and local values are entered. In ‘RIVER 1’ the
dispersion coefficient is globally set to 10 m 2 /s (independent of the flow velocity because b equals 0). In the reach between chainages 10000 m and
20000 m the dispersion coefficient is dependent on the velocity (D= 15V, 5
< D < 25)
7.7
Init. cond.
Initial component concentrations are defined on this property page. If an initial concentration is not specified a default value of zero will be applied throughout the model. Global and local values of initial concentrations can be specified for each component. Local values are specified by entering the river name, chainage and concentration in the local values table. Initial concentrations are not used if the AD simulation is started with a hotstart file.
354 MIKE 11
Init. cond.
Figure 7.7
The initial conditions property page.
Initial conditions table
Component
Here the component in question is selected. It is possible to choose between the components defined in the Components property page, see
Concentration
Here the value of the initial condition is entered.
Global
This box must be checked if the value entered in the Concentration field should be used as a global value. If it is left unchecked the value will be used as a local value.
River name
The name of the river with the local initial value.
Chainage
The chainage in the river with the local value.
Example
In Figure 7.7 two components are simulated, COMP1 and COMP2. The
initial concentration of COMP1 is set to 10.00 for the entire river network.
The initial concentration of COMP2 is set globally with a value of 2.00.
However, the initial concentration of COMP2 varies linearly between 2.00 and 7.00 in the branch ‘RIVER 1’ from chainage 10000 to 20000. From chainage 20000 to 25000 the initial concentration of COMP2 is 7.00.
Advection-Dispersion Editor
355
356
Advection-Dispersion Editor
Initial conditions - stratification table
Component
Here the component in question is selected. Presently only temperature can be selected.
Conc. S
Temperature at the surface.
Conc. 2
Temperature at layer k2 above the bottom.
Conc. 3
Temperature at layer k3 above the bottom.
Conc. B
Temperature at the bottom.
k2
Layer number above the bed
k3
Layer number above the bed.
Global
This box must be checked if the value entered in the Concentration field should be used as a global value. If it is left unchecked the value will be used as a local value.
River name
The name of the river with the local initial value.
Chainage
The chainage in the river with the local value.
MIKE 11
Decay
7.8
Decay
This page contains information for non-conservative components. These components are assumed to decay according to a first-order expression: dC dt
=
KC
(7.3)
Where K is a decay constant. C is the concentration. Both global and local values of the decay constant K can be specified. NOTE If the components selected are used for a water quality simulation (WQ) then decay constants should not be specified.
Figure 7.8
The Decay property page.
Component
Here the component in question is selected. It is possible to choose between the components defined in the Components property page, see
Decay const
Here the value of the decay constant are entered.
Global
This box must be checked if the value entered in the Decay const. field should be used as a global value. If it is left unchecked the value will be used as a local value.
Advection-Dispersion Editor
357
Advection-Dispersion Editor
River name
The name of the river with the local initial value.
Chainage
The chainage in the river with the local value.
Example
In Figure 7.8 the component COMP2 has been selected to be non-conserv-
ative. The decay constant is 1.00 globally in the river network and has a value of 2.00 in RIVER 1 between the chainages 10000 m and 20000 m.
7.9
Cohesive ST
Data used for the cohesive sediment transport models are entered on this page. When using the cohesive sediment transport models (either the simple or the advanced) all components specified in the AD editor must be defined as ‘Single layer cohesive’ or ‘Multi layer cohesive’ in the Components dialog.
The cohesive sediment transport parameters can only be accessed when a component type on the ‘Components’ page is defined as either single or multi layered. Global and local parameter values can be specified as required.
358 MIKE 11
Cohesive ST
7.9.1
Single Layer Cohesive Model
Figure 7.9
The Cohesive sediment property page when a single layer model is selected.
Below the parameters that apply to the ‘Single layer cohesive’ sediment transport model are described.
Fall Velocity
Deposition w0
The free settling velocity.
Critical shear stress/velocity for deposition
Deposition occurs for shear stresses or velocities lower than the critical value. The user can select which one to use. The typical range is: 0.03 -
1.00 N/m 2 .
Time centring
This centring factor used in the deposition formula. Typical range is: 0.5-
1.0.
Advection-Dispersion Editor
359
360
Advection-Dispersion Editor
Erosion
Critical shear stress/velocity for erosion
Erosion occurs for shear stresses or velocities larger than the critical value.
The user can select which one to use. The typical range is: 0.05 - 0.10
N/m 2 .
Erosion coefficient
The erosion coefficient is applied linearly in the erosion expression. Typical range: 0.20 - 0.50 g/m 2 /s.
Erosion exponent
The erosion exponent describes the degree of non-linearity in the rate of erosion. Typical range: 1-4.
Overview
At the bottom of the property page a overview table is shown.
Global
If this box is checked the entered parameters are used globally.
River Name
The name of the river for which the data applies.
Chainage
The chainage of the river for which the entered data applies.
MIKE 11
Cohesive ST
7.9.2
Multi Layer Cohesive Model
Figure 7.10
The cohesive sediment property page when a multi layer model is selected.
Below the parameters that apply to the ‘Multi layer cohesive’ sediment transport model are described.
Fall velocity
C-offset
Concentration limit for flocculation affected settling velocity. For higher concentrations the settling velocity is affected by hindered settling.
g
Exponent used in the settling velocity expression. Typical range: 3 - 5.
m
Exponent in the settling velocity expression for concentrations below Coffset.
w0
Free settling velocity. Typical range: 0.0025 - 0.01 m/s.
Advection-Dispersion Editor
361
362
Advection-Dispersion Editor
Deposition swi
Sediment volume index used in the settling velocity expression.
Critical shear stress/velocity for deposition
Deposition occurs for shear stresses or velocities lower than the critical value. The user can select which one to use. The typical range is: 0.03 -
1.00 N/m 2 .
Time centring
This centring factor used in the deposition formula. Typical range is: 0.5-
1.0.
Erosion
Instantaneous erosion of layer 1
Instantaneous re-suspension of layer 1 occurs when the computed bed shear stress is greater than the critical shear stress for erosion of layer 1.
Critical shear stress/velocity for erosion
Erosion occurs for shear stresses or velocities larger than the critical value.
Typical ranges are: 0.05 - 0.10 N/m 2 for layer1 and 0.20 - 0.50 N/m 2 for layer 2 and 3.
Erosion coefficient
The erosion coefficient is applied linearly in the erosion expression. Typical range: 0.20 - 0.50 g/m 2 /s.
Erosion exponent
The erosion exponent describes the degree of non-linearity in the rate of erosion. In case that ‘Instantaneous erosion’ of layer 1 is selected the erosion exponent is not applicable for layer one. Typical range: 1-4.
Consolidation
Transition rates
The consolidation of the sediment layers is described by transition rates between the layers. The transition rates include hindered settling and consolidation. Typical ranges: layer 1 -> layer 2: 2.35 - 3.11 g/m
2
/s,
MIKE 11
Cohesive ST layer 2 -> layer 3: 0.10 - 0.20 g/m2/s
Sliding friction coefficient
Coefficient used in the formulation for sliding of sediment. Typical range:
3 - 7 m 1/2 /s.
Overview
At the bottom of the property page a overview table is shown.
Global
If this box is checked the entered parameters are used globally.
River Name
The name of the river for which the data applies.
Chainage
The chainage of the river for which the entered data applies.
7.9.3
Description
Single Cohesive Layer Model - Deposition
Deposition of suspended material occurs when the mean flow velocity is sufficiently low for particles and sediment flocs to fall to the bed and remain there without becoming immediately resuspended. Particles and flocs remain on the bed if the bed shear stress is less than the critical shear stress for deposition.
The rate of deposition can be expressed by:
S
=
h
*
–
τ
τ
cd
where,
S
is the source term in the advection dispersion equation
C is the concentration of the suspended sediment (kg/m 3 )
w is the mean settling velocity of suspended particles (m/s)
h
* is the average depth through which the particles settle
τ is the critical shear stress for deposition (N/m 2 )
Advection-Dispersion Editor
363
364
Advection-Dispersion Editor
τ
cd
is the bed shear stress (N/m
2
)
The bed shear stress can be given by the Manning formula (as an example):
τ
=
ρg V
M
2
-----------------
h
(7.5) where,
ρ fluid density (kg/m 3 )
g
acceleration of gravity (m/s
2
)
M
the Manning number (m 1/3 /s)
h
flow depth (m)
V
flow velocity (m/s)
Substituting the bed shear stress into the deposition equation results in the following equation:
S
=
h
*
–
V
V cd
2
where,
V cd
critical deposition velocity.
Single Cohesive Layer Model - Erosion
The resistance against erosion of cohesive sediments is determined by the submerged weight of the individual particles and by the interparticle electro-chemical bonds which must be overcome by the shear forces before erosion occurs.
S
=
h
*
–
τ
τ
ce
n
where
S
source term in the advection dispersion equation
MIKE 11
Cohesive ST
h n
τ bed shear stress (N/m
2
)
τ
ce
critical shear stress for erosion (N/m 2 )
M
* erodibility of the bed (g/m 2 /s) (= erosion coefficient) flow depth (m) erosion exponent
Using the Manning formula as described in the deposition section above, the following expression for the erosion rate can be derived:
S
=
h
*
–
V
V ce
2
n
where
V ce
critical erosion velocity
Multi Layer Cohesive Model - Deposition
Deposition occurs when the bed shear stress is smaller than a critical shear stress for deposition. In the advanced cohesive model the rate of deposition (S
d
) is given by:
S d
=
W s
1 –
τ
b
, (7.9) where
S d
τ
c
rate of deposition (kg/m
2
/s) critical shear stress for deposition (N/m 2 ) suspended sediment concentration (kg/m
3
)
All deposited material is added to sub-layer 1.
The model concentration c is weighted in time according to the following expression:
c
=
(
1 –
θ )c
j n
+
θc
j
+
(7.10)
Advection-Dispersion Editor
365
366
Advection-Dispersion Editor where:
j n
θ spatial index time index the time centring for deposition
Multi Layer Cohesive Model - Erosion
The erosion process can be described as either instantaneous or gradual.
Instantaneous erosion occurs when the bed shear stress exceeds the critical shear stress for erosion of the sediment. This implies that all sediment is resuspended instantaneously.
The gradual erosion is described by an erosion rate assumed to be a nonlinear function of the excess stress:
S
E
=
E o
( τ
b
–
τ )
n
where,
S
E
E o
τ
c,e
rate of erosion (kg/m
2
/s) erosion coefficient (kg/s/N) critical shear stress for erosion n: erosion exponent
Both instantaneous and gradual erosion formulations can be applied to sub-layer 1. Gradual erosion is automatically applied for sub-layers 2 and
3. Thus, it is possible to describe each sub-layer separately through the parameters E
o
, and n. The erosion rate can be specified in terms of velocity or shear stresses.
MIKE 11
W Q E C O L A B E D I T O R
367
368 MIKE 11
Model Definition
8 WQ ECO LAB EDITOR
ECO Lab is a numerical lab for Ecological Modelling. It is an open and generic tool for costumizing Aquatic Ecosystem models to describe water quality, eutrophication, heavy metals and ecology. The module is mostly used for modelling water quality as part of an Environmental Impact
Assessment (EIA) of different human activities, but the tool is also applied in aquaculture for e.g optimizing the production of fish, seagrasses and mussels. Another use is in online forecasts of water quality.
The need for tailormade ecosystem descriptions is big because ecosystems vary. The strength of this tool is the easy modification and implementation of mathematical descriptions of ecosystems into the hydrodynamic engines of DHI.
The user may use the predefined ECO Lab Templates or may choose to develop own model concepts. The module can describe dissolved substances, particulate matter of dead or living material, living biological organisms and other components (all referred to as state variables in this context).
The module was developed to describe chemical, biological, ecological processes and interactions between state variables and also the physical process of sedimentation of components can be described. State variables included in ECO Lab can either be transported by advection-dispersion processes based on hydrodynamics, or have a more fixed nature (e.g. rooted vegetation).
8.1
Model Definition
The Model Definition consists of the selection of the .ecolab file, which will form the basis of the Water Quality simulation. The .ecolab file contains the definitions of the ECO Lab model. The appearance of the remaining ECO Lab Dialogs depends on the contents of this file. The .ecolab file can be selected by choosing the “From File...” item in the combo-box and browsing to the location of the file. This procedure is normally adopted for selecting user-defined .ecolab files.In case your MIKE 11 Installation includes one or more of the pre-defined DHI Water Quality models, these will be listed in the combo-box as well. Having selected the .ecolab file, a brief summary of the contents of the model is shown in the Dialog.
Please note that every time a new .ecolab file is selected, the specifications of all the remaining ECO Lab Dialogs are reset to default values.
WQ EcO Lab Editor
369
WQ ECO Lab Editor
Figure 8.1
Menu for Water Quality Model Definition
The specification of the Solution Parameters includes selection of the Integration Method for the coupled ordinary differential equations defined in the .ecolab file. At present the following three methods are available: z z z
Euler integration method
Runge Kutta 4th order
Runge Kutta 5th order with quality check
Finally the Update Frequency has to be specified. This parameter, which has to be an integer above zero, is defined such that:
The selection of the Time Step of the ECO Lab model, and hereby the
Update Frequency, has to be based on considerations of the time scales of the processes involved. Please notice that this selection can be rather decisive for the precision of the numerical solution as well as for the CPU time of the simulation. A large Update Frequency will decrease the precision as well as the CPU time. It is therefore advisable to perform a sensitivity analysis on the Update Frequency before making the final selection.
8.2
State Variables
The State Variables Dialog shows a summary of the State Variables defined in the ECO Lab model. The Description, Unit and Transport type
(“No Transport” refers to a fixed State Variable and “‘Transport” refers to a State Variable, which is transported by Advection-dispersion) of each
State Variable are given.
370 MIKE 11
Constants
Figure 8.2
The State Variables tab
For each State Variable its initial value within the model area should be specified . It can be specified in one of two ways: As a constant value applied to all points in the area or with local exceptions.
8.3
Constants
The Constants are defined as any input parameter (physical constant, coefficient, rate, etc.) in the ECO Lab model, which is constant in time. The
Constants are essentially divided into two groups: z
Built-in Constants and z
User-specified Constants
The built-in Constants are automatically provided by the model system during execution, whereas the user-specified Constants have to be specified in the present Dialog.
Depending on the Spatial Variation of the Constant, as defined in the ECO
Lab model, it can be specified as a “Constant value” or as local values.
Please note that a Constant, which is defined as a built-in Constant in the
ECO Lab model, will appear as a user-defined Constant in case it is not supported by MIKE 11.
WQ EcO Lab Editor
371
WQ ECO Lab Editor
Figure 8.3
Menu for Constants
8.4
Forcings
The Forcings are defined as any input parameter (physical property, rate, etc.) in the ECO Lab model, which is varying in time. Examples of a Forcing are: Temperature, salinity, solar radiation and water depth. The Forcings are essentially divided into two groups: z z
Built-in Forcings and
User-specified Forcings
372
Figure 8.4
Menu for Forcing Functions
The built-in Forcings are automatically provided by the model system during execution, whereas the user-specified Forcings have to be specified in
MIKE 11
Auxiliary Variables the present Dialog. Depending on the Spatial Variation of the Forcing, as defined in the ECO Lab model, it can be specified as a “Constant value” or a “Type 0 data file”. Please note that a Forcing, which is defined as a built-in Forcing in the ECO Lab model, will appear as a user-defined
Forcing in case it is not supported by MIKE 11.
Note that the forcings called "Water depth " and "Water layer height" both hold the actual hydraulic radius as a measure for the water depth rather than for instance the maximum or the average depth across the cross section.
8.5
Auxiliary Variables
Auxiliary variables or help processes, if defined in the ECO Lab file, can be stored as additional output in the '<AD filename>WQAdd.resl11' file.
The author of the ECO Lab file has decided which of the auxiliary variables described in the ECO Lab file that the user can select and store as additional output. Simply tick the auxiliary variables you want to save.
Figure 8.5
The Auxiliary Variables tab
8.6
Processes
Processes which are defined in the ECO Lab file, and at the same time marked as OUTPUT, can be saved in the '<AD filename>WQAdd.resl11' file. Also for the processes the author of the ECO Lab file has decided which of the processes that you can store as additional output. Simply tick the processes you want to save.
WQ EcO Lab Editor
373
WQ ECO Lab Editor
Figure 8.6
The Processes tab
8.7
Derived Output
Derived output defined in the ECO Lab file could be the sum of various state variables (e.g. Total N = Organic N and Inorganic N) that are useful to save in the '<AD filename>WQAdd.resl11' file without doing any manual post-processing of the main model results. The author of the ECO Lab file may have chosen other types of processed model results from which you can select the derived output. Simply tick the derived output you want to save.
374
Figure 8.7
The Derived Output tab
MIKE 11
S E D I M E N T T R A N S P O R T E D I T O R
375
376 MIKE 11
9 SEDIMENT TRANSPORT EDITOR
The MIKE 11 non-cohesive sediment transport module (NST) permits the computation of non-cohesive sediment transport capacity, morphological changes and alluvial resistance changes of a river system.
Input data concerning non-cohesive sediment properties are defined in the
ST Parameter Editor which contains the following tabs (property pages): z z z z
Sediment grain diameter (p. 379)
z z z z
Preset distribution of sediment in nodes (p. 388)
Initial dune dimensions (p. 389)
Non-Scouring Bed Level (p. 390)
Some of the sediment transport formulas and other features of the Non
Cohesive Sediment Transport module have been developed in cooperation with CTI Engineering CO., Ltd., Japan.
9.0.1
Sediment transport simulations; Simulation mode
The explicit sediment transport mode
In the explicit mode, the sediment transport computations are based either on the results from an existing hydrodynamic result file or from a hydrodynamic computation made in parallel using characteristic transport parameters. The sediment transport is calculated in time and space as an explicit function of the hydrodynamic parameters (i.e. discharge, water levels etc.) previously calculated. Note, that there is no feedback from the sediment transport calculations to the hydrodynamics. Results are volume transport rates and accumulated volumes of deposition or erosion.
The explicit mode is useful where significant morphological changes are unlikely to occur. An estimate of the sediment budget can then be obtained economically (in terms of computer time) using this mode.
The explicit sediment transport mode is active if the check box; ‘Calcula-
tion of Bottom Level’ is un-checked (in the ‘Transport model’ page).
Sediment Transport Editor
377
Sediment Transport Editor
The morphological mode
Sediment transport computations made in the morphological mode are made in parallel with the hydrodynamic computations. The morphological
mode is activated through the ‘Transport model’ tab page by activating the
check-box; ‘Calculation of Bottom Level’.The sediment transport is calculated in time and space as an explicit function of the corresponding values of the hydrodynamic parameters calculated in tandem. The sediment transport module solves the sediment continuity equation and determines the updating of bed resistance, transport rates, bed level changes and dune dimensions (depending on the transport relationship adopted), so that changes in flow resistance and hydraulic geometry due to the sediment transport can be included in the hydrodynamic computations.
The morphological simulation mode requires considerably more computation time than the explicit mode but is more representative of the dynamic alluvial processes.
9.0.2
The transport models
A variety of transport models are available. Some of the transport models determines the total sediment transport and others distinguish between bed load and suspended load. Following transport models are available: z z z z z z z z z z
Engelund - Hansen (Total load)
Ackers - White (Total load)
Smart - Jaeggi (Total load)
Engelund - Fredsøe (Bed load and Suspended load)
Van Rijn (Bed load and Suspended load)
Meyer Peter and Muller (Bed load)
Sato, Kikkawa and Ashida (Bed load)
Ashida and Michiue Model (Bed load and Suspended load)
Lane-Kalinske (Suspended load)
Ashida, Takahashi and Mizuyama (ATM) (bed load)
All of the transport models can be used for both explicit and morphological mode computations.
No general guidelines can be given for the preference of one model over another, as the applicability of each depends on a number of factors. Further details can be found by consulting the NST Reference Manual.
378 MIKE 11
Sediment grain diameter
Sediment transport is a highly non-linear function of the flow velocity.
Depending on the model used, the transport is proportional to the velocity raised to the 3rd or 4th power. Instabilities may occur in certain cases even when the hydrodynamic computation is stable. Special care must be taken in the determination of initial conditions and time step selection to avoid instability problems.
Features and usage of the ST Parameter Editor pages are described below.
9.1
Sediment grain diameter
Sediment grain diameter(s) and standard deviation(s) of grain size to be used in the sediment computations are specified in this page. The grain diameter and standard deviation may be specified as being applicable globally and locally. If grain diameters and standard deviations are specified for a local application, these values are used instead of any globally specified values.
Figure 9.1 shows an example where the sediment grain diameter is glo-
bally set to 0.5 mm. This value will be used in the entire river network except for the reaches ‘RIVER1’ between 1000 m and 2500 m, where the local grain diameter varies linearly between 1.2 and 1.5 mm. and between
2500 m and 4400 m where the grain diameter varies linearly between 1.5 and 1.1 mm. At the same chainages, the standard deviation varies linearly between 1.2, 1.2 and 1.0.
Sediment Transport Editor
379
Sediment Transport Editor
Figure 9.1
Example of implementation of local grain diameter.
9.2
Transport model
Selection of sediment transport model as well as editing the model specific parameters are essential for the calculation of the sediment transport.
This page should therefore always be checked by the user to set the model type (Total load or bed load/suspended load model), select the appropriate transport model(s) and adjust the transport parameters if required.
380 MIKE 11
Transport model
Figure 9.2
Example of implementation of transport model parameters.
Figure 9.2 shows an example of how to set the transport model type and
appropriate parameters in the dialog. In this example, the bed load transport will be calculated using the ‘Engelund and Fredsoe’ model and the suspended load transport calculated using Van Rijn formula. Morphological computation is selected as the check box for ‘Bottom Level’ is activated, but there will be no computing of the bed shear stress.
9.2.1
Model Parameters
The transport model parameters can be divided into three sub-groups:
Parameters used by the actual transport models
Spec. Gravity
Specific gravity of the sediment.
Sediment Transport Editor
381
382
Sediment Transport Editor
Kin. Viscosity
Kinematic viscosity of water.
Please note, that - using SI-Units - the Kinematic Viscosity must be specified as 'value
.
10
-6
' m
2
/s. That is, if a value of 0.000001 m
2
/s should be used, in the dialog, you must specify 1.0.
Beta
Dynamic friction coefficient used in the Engelund-Fredsoe model.
Theta Critical
Critical Shields' parameter.
In case of Ashida, Takahashi and Mizuyama (ATM) bed load model a selection box is made visible and the user can hereby select whether Theta
Critical should be calculated or if the constant value from the input page should be applied. If ‘Theta Critical calculated’ has been selected, the value of Theta Critical will be calculated from Iwagaki’s model and the modified Eqiazaroff model (for further details, see the MIKE 11 NST reference manual; section of ‘Incipient Motion Criteria’).
Gamma
Calibration parameter applied to suspended load with the Engelund-Fredsoe model when calculating the height of sand dunes.
Ackers-White
Switch used in the Ackers-White model indicating whether the applied grain size represents d
35
or d
65
.
Channel slope option (ATM bed load model only)
The Ashida, Takahashi and Mizuyama bed load model takes into account effects of channel slope on the calculated bed load. Different options are available for representing the channel slope ‘I’: I=0, I=Energy Grade and
I= bed level slope.
Storing
– Bed / Suspended load
Storing of suspended load and bed load as individual result items in the ST result file from a simulation. This feature is only applicable for those of the transport models which separates the sediment transport into bed load and/or suspended load components.
– Total sediment volumes in each grid point
MIKE 11
Transport model
Storing of total sediment volume in each gridpoint - accumulated over time. That is;
– Graded sediment volumes in each grid point
Storing of sediment volume of each fraction in each grid point.
Parameters used if a morphological computation is included
Calculation of Bottom Level
A check box is provided to include or exclude bed level updating during the simulation.
dH/dZ
Calculation parameter for the morphological model.
PSI
Centring of the morphological computation scheme in space.
FI
Centring of the morphological computation scheme in time.
FAC
Calibration parameter for computation of derivatives in the morphological model.
Note that this parameter implicitly defines the step length for a number of
numerical derivatives. For this reason the parameter must be greater than unity. If this is not the case MIKE 11 sets its value equal to 1.01 internally.
Porosity
Porosity of the sediment.
Parameters used if updating of bottom shear stress is included
Bed Shear Stress
A check box is provided to include or exclude bed shear stress updating during the simulation.
Resistance type combo box
The user is given the option to select which shear stress / resistance type formulation to be used for defining minimum and maximum limits of resistance number calculated throughout the ST simulation (Manning’s M,
Manning’s n or Chezy).
Sediment Transport Editor
383
Sediment Transport Editor
Omega
Calibration parameter for the resistance number. (ResistanceST =
OMEGA * ResistanceHD). Note that Omega is applied to the resistance number, which can be Manning’s M, Manning’s n or Chezy C depending upon user input.
Minimum/Maximum
Minimum/maximum limits for the calculated resistance number in the computations.
Please Note: If calculation of the bottom shear stress is selected in a mor-
phological computation, the updated shear stress values are used in the hydraulic computations. Thus, the Chezy or Manning number specified in the cross-section data base may differ from the value(s) applied in the hydrodynamic computations.
9.2.2
Special features for specific transport models
Engelund-Fredsoe model
When selecting the Engelund-Fredsoe transport model, dune height and dune length are computed - if calculation of Bed Shear Stress is included.
Therefore, an additional property page; ‘Initial Dune Dimensions’ is made visible in the ST Editor when either the bed load or suspended load trans-
port model is chosen as Engelund and Fredsoe, see Section 9.7.
Smart-Jaeggi model
When selecting the Smart-Jaeggi transport model, the model parameters must be edited as for all other transport models. Additionally, coefficients and exponents used in the Smart-Jaeggi formulation can be edited. Therefore, when selecting the transport model for Total Load as ‘Smart and
Jaeggi’ values for coefficients and exponents can be edited in a separate
dialog as shown in Figure 9.3.
384 MIKE 11
Transport model
Figure 9.3
Additional dialog for defining Smart and Jaeggi model factors.
The Smart - Jaeggi Factors dialog is activated by pressing the
button, which can be activated as soon as the transport model selected is ‘Smart and Jaeggi’.
Coefficients and exponents are essential for the Smart and Jaeggi transport model and a simulation should therefore not be performed until this dialog has been edited.
9.2.3
Bottom level update methods
Special options for updating the bottom level exists. The default method is to assume that the whole cross section is moved undistorted up in the case of deposition and down in the case of erosion. Alternatively, another update method can be specified in the MIKE11.Ini file. By default method no 4 is applied. A more detailed description on the calculation of bottom levels is given in the NST Reference Manual.
Update methods available are: z
Method no 1.
Deposition in horizontal layers from the bottom. Erosion proportional with depth below bank level z
Method no 2
Sediment Transport Editor
385
Sediment Transport Editor
Deposition and erosion uniformly distributed below the water surface.
No deposition and erosion above.
z
Method no 3
Deposition and erosion proportional with depth below water surface.
No deposition and erosion above.
z
Method no 4
Deposition and erosion uniformly distributed over the whole cross section (i.e. below the bank level).
z
Method no 5
Deposition and erosion proportional with depth below bank level
9.3
Calibration factors
The factors ‘Factor 1’ and ‘Factor 2’ can be applied to the calculated transport rates as correction factors.
If the sediment transport is calculated as total load (e.g. Engelund-Hansen,
Ackers-White and Smart-Jaeggi models) ‘Factor 1’ is used as the correction factor, whereas for other models distinguishing between bed load and suspended load, ‘Factor 1’ is used as a multiplication factor for Bed load transport and ‘Factor 2’ as a multiplication factor for suspended load transport. Calibration factors can be specified globally and locally as
shown in Figure 9.4, where ‘Factor 1’ and ‘Factor 2’ are globally defined
as 1.0, but varies linearly with values different from the global in the river reach ‘RIVER1’ chainage 1000 to 4000 m.
386 MIKE 11
Data for graded ST
Figure 9.4
Calibration factors dialog
9.4
Data for graded ST
The required input data for the simulation of graded sediment transport and sediment sorting are specified on this property page.
The bed material is represented by two layers, an active layer overlying an inactive, passive layer. Each layer is divided into an equal number of fractions (or classes) specified by the user. A mean grain size (mm) for each fraction and the percentage distribution for both the active and the passive layers must be specified. The fraction mean grain sizes are global but the initial percentage size distributions may be specified globally or locally.
The sum of the initial percentage distributions for both the active and the passive layers must equal 100%.
It is possible to specify a lower limit for the active layer depth ('Min. depth active layer') and an initial depth for the passive layer.
The effects of shielding can also be included by setting a check mark in the ‘Shielding of particles’ checkbox.
The percentage contribution and transport rate of each fraction can be stored in the result file by setting a check mark in the ‘Save fraction values’ and ‘Save sed. transport each fraction’ check boxes. If the result file is to be used as a hot start file, the values must be saved.
Sediment Transport Editor
387
Sediment Transport Editor
Global and local values can be specified.
An example of defining 4 fractions (global defined fractions only) is
Figure 9.5
Example of specifying Graded ST data (4 fractions)
9.5
Preset distribution of sediment in nodes
The default distribution at a node is carried out according to the ratio of flow discharges. An alternative distribution can be specified on this property page by providing the coefficients and the exponents (K and n values) in the following relationship:
Qt
n 1
m
+
=
∑
m n
Q m m
K i
Q i n i
downstream branches
∑
upstream branches
Qt j
+
Where
Qt
n 1
m
+ sediment transport rate in branch m
(9.1)
388 MIKE 11
Passive branches
The coefficients and exponents are given for each branch, specified by its upstream and downstream chainage, linked to the node. The property page also enables the addition and editing of a preset distribution of sediment in nodes related data.
9.6
Passive branches
Branches in which sediment transport should not be calculated are specified by river name and upstream and downstream chainage as shown in
Figure 9.6. Sediment can be transported into a passive branch, but no sed-
iment can be transported out of the branch.
Figure 9.6
Passive branches property page.
9.7
Initial dune dimensions
When selecting the Engelund-Fredsøe transport model the dune height and length are computed when calculation of bottom shear stress is included. The dune dimensions can be specified as applicable globally and locally. If dune dimensions are specified for local application, these values will be used instead of any globally specified values.
Figure 9.7 shows an example where the global dune height has been set to
0.25 m, and the global dune length has been set to 12.50 m. These values will be used in the entire river network, except in the reach ‘RIVER1’,
Sediment Transport Editor
389
Sediment Transport Editor between chainage 5.000 km and 10.000 km, where the dune height varies linearly between 0.25 m and 0.40 m.
Figure 9.7
Example of an implementation of local initial dune dimensions.
If no dune dimensions are given, or the dune height and length equals zero, then the dune height will be calculated as the water depth divided by
6 with a dune length of 15 times the water depth.
9.8
Non-Scouring Bed Level
The Non Scouring Bed Level page offers the possibility of defining two parameters; thickness of active layer and a non scouring bed level.
The Thickness of active layer is used in the Graded sediment transport calculations. Default formulations in MIKE 11 defined the thickness of active layer as half the dune height, but now the value can be user-defined.
The value must be given as a depth. That is; a height above bottom of river bed.
Please note: Setting the Thickness of active layer to a value of -99
switches back the formulation to the previous default formulation in
MIKE 11 (thickness equal half the dune height).
The Non scouring bed level item gives a possibility for the user to define levels (global and/or locally) where a non-erodible surface is present.
390 MIKE 11
Non-Scouring Bed Level
(Important to notice, that this item must be defined as a level - and not a height!) If, during a morphological simulation, bed erosion occurs and the bottom of the bed reaches the defined Non scouring bed level, no further bed erosion will take place.
Figure 9.8
Non scouring Bed Level property page
Figure 9.8 shown an example where the global values of Thickness of
active layer is defined to 0.1 m and Non scouring bed level is set to -1.5 m.
These values are used in the entire river setup except for specific reaches in ’RIVER1’ and ’RIVER2’ where local values are specified. Linear interpolation will be used to define Layer thickness and Non scouring level at calculation points in between the local stations defined in the dialog.
Please notice, that in ’RIVER2’ from chainage 0 to 4000 a value of -99 has been defined which means, that the previous default formulation for defining thickness of active layer in MIKE 11 will be activated for this river reach.
Sediment Transport Editor
391
Sediment Transport Editor
392 MIKE 11
F L O O D F O R E C A S T I N G E D I T O R
393
394 MIKE 11
Basic definitions
10 FLOOD FORECASTING EDITOR
The MIKE 11 Flood Forecasting Module (MIKE 11 FF) has been designed to perform the calculations required to predict the variation in water levels and discharges in river systems as a result of catchment rainfall and runoff and inflow / outflow through the model boundaries.
The MIKE 11 FF module includes: z z z z
Definition of basic FF parameters
Definition of boundary conditions in the forecast period (Forecasted boundary conditions)
Definition of Forecast stations
An updating routine to improve forecast accuracy. The measured and simulated water levels and discharges are compared and analysed in the hindcast period and the simulations corrected to minimise the discrepancy between the observations and model simulations.
10.1 Basic definitions
10.1.1 Simulation Period and Time of Forecast
The Time of Forecast (ToF) is defined in relation to the Hindcast and the
Forecast Period in Figure 10.1.The Hindcast Period defines the simulation
period up to ToF and is specified in the simulation file or calculated by the
system; see Chapter 10.1.2, Simulation Mode. The length of the Forecast
Period is always specified in the Forecast Menu, see section 10.2.1
Figure 10.1
Definition of ToF
10.1.2 Simulation Mode
Real-time mode
Real time mode defines a condition where MIKE 11 FF is used to execute simulations applying real-time hydrometeorological data as boundary conditions. The common time span of the boundary data defines the hind-
Flood Forecasting Editor
395
Flood Forecasting Editor
cast period, see Figure 10.2. As real-time hydrological and meteorological
data are often captured and supplied by a telemetry network, pre-processing of these data is usually required for a specific (user defined) Hindcast
Period and Time of Forecast.
396
.
Figure 10.2
Definition of Hindcast Period and ToF
Historical mode
While real-time telemetry data form the boundary conditions in an operational forecasting mode, historical hydrometeorological data are applied as boundary conditions in the calibration and validation phase of forecast modelling.
When MIKE 11 FF runs in historical mode, the hindcast period is defined via the Simulation Menu in the sim11 editor. The Hindcast Period is defined from Simulation Start to Simulation end i.e. Simulation end is interpreted as ToF.
In the example shown below in Figure 10.3 the hindcast period starts on
the 4 January 1999 at 12:00 and last up to 7 January 1999 at 12:00.
Figure 10.3
Definition of Hindcast period in historical mode
The forecast period is defined in the Forecast Menu.
MIKE 11
Forecast
10.2 Forecast
The main forecast parameters are specified in the Forecast Menu,
Figure 10.4
Basic Forecast Definitions
10.2.1 Forecast length
The Forecast length is equal to the Forecast Period (Figure 10.4). The
length of the Forecast Period can be specified in hours or in days
10.2.2 Include updating
Tick on the appropriate check box to include the updating routine. Update points and parameters are specified on the Update Specification menu;
10.2.3 Accuracy
The Boundary Conditions estimated after the Time of Forecast are obviously uncertain. The effect of a specified uncertainty level can be included in the simulations.
Flood Forecasting Editor
397
Flood Forecasting Editor
Tick on the ‘Include uncertainty level’ check box to include.
Specify either global and/or local values for the deviation. Global values are applied to all catchments or HD boundary conditions, except those which are listed in the ‘Local Values’ fields.
Estimated boundary conditions with Upper and Lower levels are stored in
the ‘Boundary Estimates’ directory as described in Section 10.3.4.
10.2.4 Alternative Modes
Multiple forecast with historical data
To execute simulations in Historical Mode tick on the Multiple forecast
check box, see Figure 10.4 or below. Additional information about simu-
lating in Historical Mode can be found in Section 10.1.2.
In Historical Mode it is possible to execute consecutive simulations shifting the Start time and ToF of each simulation. Simulation start and ToF applied in the first simulation are defined on the simulation menu in the sim11 editor.
Figure 10.5
Selection of Historical Mode
No of FC defines the number of consecutive simulations to be executed
and Step defines the interval at which multiple forecasts are made. The
Time of Forecast (ToF) is moved forward Step (hours) between forecasts
398 MIKE 11
Forecast
Figure 10.6
Multiple simulations in Historical Mode
Simulation no. 1 is executed according to Simulation Start and Simulation
End found in the Simulation Menu in the Sim11 editor. As described in
Section 10.1.2, Historical Mode, Simulation End is interpreted as ToF In
each of the following simulations Simulation Start and ToF are shifted 12 hours.
Seasonal forecasting
Not yet implemented
10.2.5 Location of forecast stations
Forecast points are specified as shown in Figure 10.7 below
Figure 10.7
Location of Forecast Points
Simulated water level or discharge at a forecast point is extracted from the
MIKE 11 HD resultfile and stored together with the “Danger level” as individual time series files (dfs0 format), one file for each forecast point
(location). These files are named according to the Name field in the Loca-
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Flood Forecasting Editor tions menu and are stored in a directory structure as illustrated in
Figure 10.8
Forecast data directory structure
MIKE 11 FF generates a data sub-directory, named according to the ToF,
e.g “8-jul-1999-12-00” in the example shown in Figure 10.8. The individ-
ual forecast time series are stored in a sub-directory named “Forecast”
Save all Forecasts
Tick off the “Save all forecasts” check box to avoid generating the individual forecast time series according to the specifications from the Location menu.
Storage timestep
The storage frequency of forecast results can be more or less frequent than the general MIKE 11 HD storage frequency specified in the Results menu in the sim11 editor.
10.3 Boundary estimates
To simulate beyond the ToF requires boundary conditions for the forecast period i.e rainfall, evaporation and possibly temperature for each catchment in the RR simulation and water level or discharge for each of the open boundaries in the HD model.
Boundary conditions applied during the forecast period are in this manual described as Estimated boundary conditions.
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Boundary estimates
Estimated boundaries can to some extent be defined by the FF module using boundary conditions from the hindcast period. Details about these
options can be found in Section 10.3.3.
Figure 10.9 shows the Boundary Estimates menu.
Figure 10.9
Boundary Estimates
10.3.1 Setup
Specify catchment name (RR) or River name and Chainage (HD) to locate the actual boundary
Type
Specify the appropriate data type:
RR: Rainfall, Evaporation, Temperature, Irrigation and Abstraction
HD: Water level, discharge or gate level.
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Filename
Press the “...” button to select the appropriate time series file.
Filetype
The Axis type for the dfs0 files applied in the forecast period can be either
‘Calendar axis’ or ‘Relative axis’. If a dfs0 file is based on a ‘Relative time axis’ the start time of that particular time series will be interpreted as
ToF.
10.3.2 Editing
All files included in the setup menu will be listed in the ‘Editing’ menu as
seen in Figure 10.9 above. Pressing the “Edit” button will start the MIKE
Zero time series editor with the actual time series loaded. In this manner it is possible to view and edit the boundary estimate time series.
10.3.3 Boundary data manipulation
To minimize the time spent entering and editing data related to the ‘Estimated boundaries’ several alternative boundary estimation methods have been implemented in the FF module. The different boundary estimation
methods are summarised in Table 10.1 and their effect illustrated in
Figure 10.10 through Figure 10.14.
Omit a boundary condition.
A boundary condition time series (i.e. rainfall / evaporation or discharge / water level time series) is simply omitted in the ‘Setup’ list.
Table 10.1
Case Estimation method
Omit a boundary condition in the ‘Setup’ list
If data from the hindcast time series cover the forecast period, these are applied. Otherwise the hindcast value at ToF is applied.
Illustration
The time series covers at least the whole forecast period.
No manipulation is required.
Estimated time series starts at ToF but does not cover the whole forecast period
Time series is extrapolated applying the last found value
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Boundary estimates
Table 10.1
Case
Estimated time series starts after ToF.
Time series is interpolated using hindcast data at ToF and the first entered estimated value
The time series cover the whole forecast period, but there is a discontinuity at
ToF
Estimation method
During the first 10 HD time steps the boundary data are interpolated between hindcast data at ToF and estimated data
Illustration
Figure 10.10 Extrapolation from value at ToF
Figure 10.11 Estimated boundary conditions as specified.
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Figure 10.12 Extrapolation of Estimated boundary conditions
Figure 10.13 Interpolation of Estimated boundary condition
MIKE 11
Update specifications
Figure 10.14 Discontinuity at ToF
10.3.4 Storing of Estimated boundaries
Estimated boundaries are stored for each forecast in a similar manner to the simulated levels or discharges from the forecast stations, see Section
10.2.5 and Figure 10.15 below.
Figure 10.15 Estimated boundary directory structure
10.4 Update specifications
The purpose of updating is to evaluate and eliminate deviations between observed and simulated discharges/water levels in the Hindcast Period to improve the accuracy of the model results in the Forecast Period. Phase and amplitude errors are identified by the updating routine and corrections in the hindcast and the forecast period are subsequently applied.
Figure 10.16 shows the Update Specification menu.
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Flood Forecasting Editor
Figure 10.16 Update Specification
10.4.1 Comparison
Station
The location of the update point is defined via its River name and Chainage. If the specified chainage does not correspond to the computational network it is shifted to the nearest h- or Q-point by the FF module and a warning message is issued.
Data type
The Data type can be specified as water level or discharge. In general, water level data should be specified at all sites where level forecasts are to be issued, and discharge at reservoir inflow points.
Discharge updating is generally preferable and should be selected at all forecasting locations where reliable discharge data are available.
Measured time series
The updating routine compares measured and simulated data. The time series of measured water level or discharge data must be specified.
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Update specifications
Method
Iterations
See No. of Iterations
Implicit solution
The specified time series are applied as internal boundary conditions in the model. In the Continuity Equation h
n+1
is substituted by the observed water level and the lateral inflow q
n+½
is calculated and applied as the updating discharge.
No. of iterations
If a river branch includes a number of update points the specified No. of iterations should be equal to or larger than this number. For large rivers with few update points it may increase the update efficiency to use an even larger number of iterations. Different numbers of iterations should be tested before operational forecasting is initiated. A larger number will increase the accuracy but also increase the required calculation time.
Frequency
Frequency of updating, i.e. the number of MIKE 11 HD time steps between data observations in the time series used for updating.
10.4.2 Correction
The updating routine will calculate a correction discharge to be routed into the river system along the correction branch. The correction branch is specified by River name, First chainage and Last chainage.
If the specified chainages does not correspond to the computational grid they are modified by the FF module and a warning message is issued
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10.4.3 Parameters
Table 10.2
Parameter Main effect
Max phase error Higher phase errors are automatically reduced to this value
Typical value
Equal to AP
Analyse Period
(AP)
Time constant in
AP
Determine the period where observed and simulated data are analysed
Found by calibration
If less than AP, recent deviations may be given more weight
Equal to AP
Time constant in forecast period
Adjust factor
Corrections at ToF are gradually decreased in the forecast period by a first order decay with this time constant.
Found by calibration
Increasing/decreasing the calculated updating discharge
1.0
Alpha
Peak value
An increase in Alpha will cause deviations to be interpreted more as amplitude errors
Found by calibration
Highest expected discharge after applying the correction discharge
From observed discharge hydrographs
10.5 Rating curves
Not implemented.
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D A T A A S S I M I L A T I O N E D I T O R
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11 DATA ASSIMILATION EDITOR
The Data Assimilation editor is used for specifying the parameters needed when carrying out z z z
Uncertainty estimation
Model updating
Forecasting
The uncertainty assessment and updating methods are applicable to hydrodynamic and/or advection dispersion simulations. Uncertainty assessment and updating for NAM rainfall runoff will become available in a later release. Thus any reference to catchment modelling in the present interface should be neglected. One exception being that the uncertainty may be applied to output from catchments.
Uncertainty assessment
The uncertainty assessment is a powerful tool for evaluating the effect of uncertainties on the boundary conditions in a river network. To carry out an uncertainty assessment a minimum of input parameters is required from the user.
Model updating
If reliable measurements are available within the model domain, these may be utilized to improve the model results of MIKE 11 using updating.
Two different updating methods are available: z z
A Kalman filter procedure
A combined weighting function and error correction procedure
Forecasting
With the appropriate data the updating routines of MIKE 11 can improve model results prior to a time of forecast. After the time of forecast the model is corrected using forecasts of errors identified prior to the time of forecast. The type of error correction to be applied in the forecast period depends on the option chosen for model updating. If the Kalman filter is applied, estimated errors in the boundary conditions at the time of forecast are phased out according to an exponential decay. If the combined weighting function and error correction procedure is applied, errors at measurement points are forecasted. Thus, the updating algorithm has an effect also after the time of forecast. Furthermore, by using the Kalman filter procedure a stochastic or ensemble forecast may be generated.
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11.1
General
Data Assimilation editor
Depending on the method applied different menus within the editor are required.
Figure 11.1
The general data assimilation model parameter tab. Note that depending on the choice made in the Module selection section one or more of the other boxes will be made inactive.
11.1.1
Module selection
The simulation mode is selected here. Either the model is run using measurement update or uncertainty assessment.
The first option requires the user to choose which updating technique that should be applied. The choices are: z
Kalman filter: The model uses the ensemble Kalman filter based on
Monte Carlo simulation techniques to estimate the updates to be applied.
412 MIKE 11
General z
Weighting function: The model uses user-defined weighting functions to estimate the updates to be applied.
If the uncertainty assessment option is chosen, the model uses Monte
Carlo simulation to propagate uncertainties in the boundary conditions into uncertainties in the simulated model output.
11.1.2
Basic parameters
Depending on the simulation mode selected in the Module selection box
the user is required to supply additional data.
Ensemble size
If applying either the uncertainty assessment simulation method or the
Kalman filter updating method, the user is required to supply the ensemble size. The ensemble size is defined as the number of simultaneous runs that are to be carried out to evaluate the statistical properties needed for the uncertainty assessment output and also for determining the updating parameters applied in the Kalman filter.
The quality of the statistical estimates are strongly dependent on the ensemble size. The larger the ensemble size the higher the confidence in the results. On the other hand, the ensemble size has a linear effect on the run time, that is, when the ensemble size is doubled the run-time is also doubled.
The above considerations should be taken into account when choosing the ensemble size. Recommended values are 50-200. If only reliable estimates of standard deviations are of importance, a smaller value may be chosen.
When producing confidence intervals an estimate of the full uncertainty distribution is needed, thus an increase in the ensemble size is recommended for such cases.
When applying the weighting function method no stochastic element is applied in the simulation and thus the ensemble size is not required.
First filtering time step
This option is only applicable when using updating. The user needs to specify at which time step the updating is to be initiated. The default value is 0 corresponding to the first time step. The use of this variable is to ensure that the stochastic process is sufficiently evolved to give good estimates of the uncertainty before the first update, thereby avoiding model stability problems.
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11.1.3
Forecast
The forecasting parameters are only applicable to the updating methods.
The time of forecast should be within the simulation period specified in
When using the Kalman filter, the user may select either a deterministic or a stochastic forecast. The first uses the ensemble mean of the state variables including corrections at the time of forecast for a deterministic run, whereas the latter continues the stochastic run omitting the updating step.
11.2
Measurements
414
Figure 11.2
The Measurements tab. Depending on the choice made in the general tab some fields are made inactive.
The measurements page is used for specifying the location and parameters of the measurements that are to be used for the updating. Note that the page is only used when applying the updating option.
To add a new measurement place the cursor in the last row in the overview and press the right tab until an additional row appears.
MIKE 11
Measurements
11.2.1
Measurement location
The location of the measurement is specified here. The location does not have to coincide with a grid point location since MIKE 11 uses linear interpolation for determining the simulation value at the appropriate measurement location.
Branch Name
The branch name where the measurement is located is specified.
Chainage
The chainage of the measurement is specified.
Variable Type
Presently three types of measurements may be applied: z z z
Water level
Discharge
Concentration
If a concentration measurement is selected, the component number is
required. The component number is given by the order found in the Components page of the AD editor.
File
The location of the measurement data is required. The dfs0 file may be selected by browsing.
11.2.2
Standard deviation
When the Kalman filter updating method is applied, the user must specify the standard deviation for the measurement. The standard deviation may be of three different types: z z
Constant. The user specifies a constant value.
Relative. The standard deviation is taken as a relative value of the measurement.
z
Time dependent. The standard deviation may vary with time with the variation defined in a dfs0 file.
When applying a relative or time dependent standard deviation, the user may apply bounds on the standard deviation.
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Data Assimilation editor
Note that for the percentage option the percentage is taken based on the absolute value for discharge and concentration. For water level the percentage is interpreted as being with respect to the water depth.
For the weighting function method the standard deviation box is not applicable.
11.2.3
Weighting function
When the weighting function update procedure is applied a weighting function must be specified for each measurement. This function defines how errors at the measurement location are distributed to neighbouring points in the river network. The procedure updates the parts of the model state that correspond to the measurement variable (e.g. if water levels are measured the water level grid points are updated), whereas the other parts of the model state are implicitly updated according to the numerical scheme in the next time step.
Type
Three different types of weighting functions are available: z z z
Constant. In this case the error correction at the measurement location is distributed evenly over the grid points between Lower and Upper chainage.
Triangular. In this case the error correction is linearly decreasing from the measurement location to 0 at the Lower and Upper chainage.
Mixed exponential. In this case the error correction is decreased according to an exponential function from the measurement location to the Lower and Upper chainage to about 0.01 times the correction at the measurement location.
Amplitude
The Amplitude specifies the fraction of the observed error at the measurement location that should be applied as error correction at that point. The
Amplitude should reflect the confidence of the observation as compared to the model forecast. That is, if the amplitude equals one, the measurement is assumed to be perfect, whereas for smaller amplitudes less emphasis is put on the measurement as compared to the model forecast.
Lower chainage
The Lower chainage specifies the lower chainage point in the branch where the measurement point is located for which the weighting function is applied.
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Measurements
Upper chainage
The Upper chainage specifies the upper chainage point in the branch where the measurement point is located for which the weighting function is applied.
Fade up
The user specifies the number of time steps used to fade up the corrections initially, starting from zero corrections at the first time step up to full corrections after the fade-up period. Employment of this function ensures that model instabilities are avoided because the desired error correction value is obtained gradually rather than abruptly.
11.2.4
Error forecast model
The weighting function update procedure may be combined with error forecasting at measurement points in the forecast period. In this case the
Apply error forecast tick box is activated and the name of the error forecast model is chosen from the pull-down menu. The error forecast model is defined in the Equation editor.
Up to the time of forecast the observed errors at the measurement locations are distributed to the neighbouring grid points according to the defined weighting functions. After time of forecast the defined error forecast models are used to forecast the errors at the measurement locations which are then distributed to the neighbouring points. Thus, by applying error correction the model is updated also in the forecast period. If error correction is not applied, updating is not performed in the forecast period, and the model forecast is simply a normal MIKE 11 run using the updated model state at the time of forecast as initial conditions.
The Error forecast model tick box is not applicable for the Kalman filter method.
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11.3
Equation Editor
Data Assimilation editor
Figure 11.3
The Equation Editor tab.
The Equation editor is used to define the error forecast models used in the weighting function update procedure. Error forecast models can be defined as general linear or non-linear functions with a one-step ahead prediction that depends on the previous errors at the measurement location, the model state at any grid points in the river network, and the boundary conditions (or any other time series defined in a dfs0 file).
11.3.1
General
To add a new equation place the cursor in the last row in the Overview of
Error Forecast Model Equations and press the right tab until an additional row appears.
Name
Unique name of the defined equation. This name is shown in the pulldown menu of available equations when defining an error forecast model for the Weighting function method on the Measurements page.
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Equation Editor
Equation
The equation editor is based on an equation parser that uses the general arithmetic operators: z z z
Addition (+)
Subtraction (-)
Multiplication (*) z
Division (/)
In addition, a number of mathematical functions are supported, see
Table 11.1
Mathematical functions used by the equation parser (X and Y are variable names).
Syntax
SQR(X)
SQRT(X)
SIN(X)
COS(X)
TAN(X)
COTAN(X)
Function
Square function
Square root function
Sine function. SIN returns the sine of the angle X in radians.
Cosine function. COS returns the cosine of the angle X in radians.
Tangent function. TAN returns the cosine of the angle
X in radians.
Cotangent function. COTAN returns the cosine of the angle X in radians.
ArcTangent function ATAN(X)
EXP(X)
LN(X)
LOG(X)
SINH(X)
Exponential function
Natural logarithmic function
10 based logarithmic function
Sinus Hyperbolic function
COSH(X) Cosine Hyperbolic function
INTPOW(X,Y) The INTPOW function raises X to an integer power Y, e.g. INTPOW(2, 3) = 8. Note that the result of
INTPOW(2, 3.4) = 8 as well.
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Table 11.1
Mathematical functions used by the equation parser (X and Y are variable names).
Syntax
POW(X,Y)
ABS(X)
SIGN(X)
TRUNC(X)
MIN(X,Y)
MAX(X,Y)
E(L)
Function
The POW function raises X to any power Y
Absolute value
SIGN(X) returns -1 if X<0; +1 if X>0, 0 if X=0.
Discards the fractional part of a number, e.g.
TRUNC(3.2) is 3.
Minimum of X and Y, e.g. MIN(2, 3) is 2.
Maximum of X and Y, e.g. Max(2,3) is 3.
Error function with lag L (L<0), e.g. E(-1) is the error at the previous time step.
As an example, suppose the error forecast model is to be expressed as a function of the variables X1, X2 and X3 as 5 times variable X1 minus the square of variable X2 plus 2 times the natural logarithm of X3, the Equation field should be written:
5*X1-SQR(X2)+2*LN(X3)
If one wants to apply a second order auto regressive model, the Equation field should be written:
A*E(-1)+B*E(-2) where A and B are the auto regressive parameters.
Estimation period
For parameters defined as values in the equation, automatic parameter estimation can be applied based on the record of observed errors. The period of the record to be used for the parameter estimation can be specified relative to the time of forecast.
This option allows parameters of the error forecast models to be updated continuously, and hence the error forecast models to adapt from one forecast to the next to the prevailing conditions at the time of forecast. For instance, the error forecast models can be adapted to the structural differences in the model errors that are often seen for different flow regimes.
MIKE 11
Equation Editor
11.3.2
Parameter definition
To add a new parameter place the cursor in the last row in the Overview of
Equation Parameters and press the right tab until an additional row appears.
Name
Unique name of parameter specified in the equation.
Type
Three different parameter types are available: z z z
Value. The parameter is assigned a numerical value.
Time series. The parameter is assigned a time series defined in a dfs0 file. This may be a boundary condition in the HD or AD setup or a rainfall input.
State variable. The parameter is assigned a state variable, i.e. a water level, discharge or concentration at a grid point in the river network.
Estimated
For a parameter that is assigned a numerical value, automatic parameter estimation can be applied to estimate the value from the time series of errors. Otherwise the value should be specified by the user in the Value field.
Value
Numerical value assigned to the parameter. If the Estimated tick box is active, this field is made inactive.
Minimum
Allowable lower bound on the parameter when automatic parameter estimation is adopted.
Maximum
Allowable upper bound on the parameter when automatic parameter estimation is adopted.
Variable type
If the parameter is defined as a state variable, the variable type should be defined: z z
Water level
Discharge
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Data Assimilation editor z
Concentration
Component number
If a concentration variable is selected, the component number is required.
The component number is given by the order found in the Components
page of the AD editor.
River name
The river name of the grid point of the state variable.
Chainage
The chainage of the grid point of the state variable.
File
If the parameter is defined as a time series, a dfs0 file item must be specified.
11.4
Boundary Statistics
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Figure 11.4
The Boundary Statistics tab.
MIKE 11
Boundary Statistics
This menu is only applicable to the Kalman filter updating method and the uncertainty assessment simulation modes. The structure of this page has been chosen to facilitate that the same uncertainty statistic can be applied to multiple boundaries. For instance, it may be that the user would like to apply a standard deviation of say 10 percent to all discharge boundary conditions in the set-up.
11.4.1
Details
The details for the boundaries where uncertainty is to be applied are specified here.
Boundary Type
The boundary types that uncertainty may be applied to are: z z z
Water levels
Discharges
Lateral source point inflows z z z z
Q/h-relations
Output from catchments
Concentrations
Wind fields
Note that at present uncertainty cannot be attributed to distributed lateral discharge sources. Also note that the interface has been prepared for including updates on rainfall runoff models, though the present release does not include any rainfall runoff update capabilities.
Once the boundary type has been selected the locations where the uncertainty is to be applied is entered in the second of the upper tables. Use the tab key on the keyboard to supply additional locations. A location is specified through a branch name and a chainage. If a concentration is to be given, the component number is also required. The component number is
given by the order found in the Components page of the AD editor. For
rainfall/runoff, only the catchment name needs to be specified. Wind fields in MIKE 11 can be of two types either distributed or global. If a distributed wind field is to be augmented with uncertainty, then the chainage where the distributed wind source starts is required. If uncertainty is to be described for the global wind field, then the river name should be chosen as ‘GLOBAL WIND’ without a chainage.If the user-supplied location does not coincide with a boundary/forcing term, a warning is issued and the boundary information is ignored in the subsequent simulation.
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Data Assimilation editor
For wind fields and catchments two standard deviations must be supplied since both of these types consist of two input variables. That is, wind velocity and wind direction for a wind field, and runoff and net rainfall for a catchment.
The specific standard deviation is defined in the Standard deviation editor
and may be selected from a pull-down menu.
The lower window gives an overview of all the boundary statistics.
11.5
Standard deviation editor
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Figure 11.5
The Standard Deviation Editor tab.
The standard deviation editor is used for defining the different standard deviations that may be applied at the boundaries.
The page is structured as a table, the columns of which are described below.
MIKE 11
Standard deviation editor z z
ID: For each standard deviation an ID is chosen. This ID can be any string, although it must be unique within the list of standard deviations.
It is used when selecting which standard deviation to apply in the
Data Type: The standard deviation is of a certain data type e.g. a standard deviation on water level requires a unit in the form of a length. The type required for the different boundary types is described in
Table 11.2
Boundary type and corresponding data type
Boundary type Data Type
Water Level
Discharge
Lateral inflow
Q/h relation
Water Level
Discharge
Discharge
Water Level
Wind Field
Output from Catchment
Wind Direction and wind speed
Discharge and Rainfall
Concentration Concentration
Input to Catchment (not available yet)
Rainfall, temperature and evaporation z z z z z
Standard deviation: The method by which the standard deviation is to be determined is selected. The choices are constant, relative and time series. A relative standard deviation is selected as a percentage of the value found in the boundary at that specific time step. The percentage is taken based on the absolute value for discharge, concentration, wind velocity, runoff, and net rainfall. For water level and Q/H-rating curves the percentage is interpreted as being taken from the water depth.
File/value: Depending on the choice made in the previous column the user supplies a constant value, a percentage or a time series with the temporal variation of the standard deviations to be used.
Item: This column is only of importance when selecting a times series.
Limits: For a relative and a time series type of standard deviation bounds may be applied. Thus the standard deviation is limited by these bounds.
TC before and TC after TOF: Explained below.
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The errors applied at the boundaries may be described through a first order auto regressive process:
ξ
=
φξ
n
+
ε (11.1) where
ξ
n
the error at time step n
φ the regression coefficient
ε white noise
The regression coefficient should be interpreted as the ‘memory’ of the model error. To ensure that this ‘memory’ is independent of the time step used the user is required to specify a time constant instead. The relation between the regression coefficient and the time constant is:
φ
= exp
–
T
½
(11.2) where
∆t the simulation time step ln the logarithm with base e.
T
½ the time constant TC.
The time constant TC should be interpreted as the time it takes for the correction to drop to half the initial magnitude (exponential decay). For wind fields and Catchment runoff, two values must be supplied. The numerical value of the regression coefficient must be less than unity to ensure that the variance of the model error is limited. A negative time constant results in a regression coefficient which is greater than unity. Therefore, if a negative time constant is entered, a warning is issued and the regression coefficient is set to 0 in the simulation.
As an option, the time constant used when forecasting may differ from the time constant used for updating. Thus, all in all up to four time constants should be supplied by the user.
The model errors being described through the auto regressive process are used in the forecast period to generate errors to be added to the bounda-
MIKE 11
Output
11.6
Output
ries. If the forecast is deterministic, the model errors are described through the auto regressive process without adding white noise. The model errors fade out according to an exponential decay.
Figure 11.6
The Output selection tab.
The Output page is used for specifying additional output from an uncertainty assessment analysis or a Kalman filter update. The output page is split in two; one for hydrodynamic output and one for advection dispersion output. For both types the user may select the following output: z z z
Standard deviation
Corrections (the corrections of the state variables in the river network caused by updating with each of the measurements)
Confidence intervals
The latter requires the user to specify a percentage for each confidence
interval. For example in Figure 11.6 as additional output two confidence
intervals (75% and 90%) along with the standard deviation have been selected for the hydrodynamic variables consisting of water level and discharge. Thus, in the additional HD result file these confidence intervals
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Data Assimilation editor and the standard deviation in the whole network will be stored. Further, in
Figure 11.6 two confidence intervals have been chosen for the advection
dispersion components. These confidence intervals are stored in the additional AD result file.
11.7
A step by step guide to uncertainty assessment
Uncertainty assessment may be carried out for hydrodynamic and/or advection dispersion. Below follows a step-by-step guide for how to setup an uncertainty assessment model.
1 Set up the MIKE 11 model as a pure deterministic model i.e. no data assimilation.
2 In the simulation editor activate the ‘Data assimilation tick box’.
428
Figure 11.7
Selecting the Data assimilation mode in the simulation editor.
3 Create a new data assimilation file (extension ‘.DA11’).
4 Make sure that this file is connected with the simulation file by selecting the created DA11 file in the DA parameters box in the input tab of the simulation editor.
Figure 11.8
Selection of the data assimilation file.
5 Open the DA parameter file.
6 Select ‘Uncertainty prediction’ in the General menu.
MIKE 11
A step by step guide to uncertainty assessment
7 Choose the ensemble size. Remember that the larger this number the more accurate the uncertainty assessment, the trade-off being longer run times. A value of 100 is recommended if feasible.
8 Consider boundary conditions applied to the model of the type
– Water level
– Discharge
– Q/H-relation
– Wind
– Source point lateral discharge
– Concentration
– Output from Catchment
For each of these boundaries consider which are to be assessed with respect to uncertainty.
9 Based on the selection above the boundaries are added in the DA editor. Note that the same boundary statistics may be applied to multiple boundaries of the same type. Thus, for instance a 10 percent uncertainty can be added to all discharge boundaries by selecting all the locations in the second box as shown below.
Figure 11.9
Multiple locations with the same boundary statistics. The same statistics will be applied to the upstream boundaries in main stem,
STtrib1 and STtrib2. To add a line place the cursor in the last line or if no lines are present in the upper left hand corner and use the right tab key on the keyboard.
Once the uncertainties have been decided upon the Standard Deviation
Editor is used to define the individual standard deviation items. The standard deviation is given an ID. This ID is subsequently used for
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Data Assimilation editor selecting which Standard Deviation to apply to the individual boundaries. Further, set the standard deviation method to be used:
– constant, a value is specified in the value/file field
– relative, a percentage is specified in the value/file field
– a time series, a file name and a time series is specified by browsing.
If a relative or a time series type of standard deviation is selected, specify (optionally) an upper and a lower limit to be applied.
10 Finally, the time constant for the temporal development of the errors are set. Only the time constant prior to the time of forecast is used. The time constants describe the “colouring” of the noise. If pure white noise is to be applied at the boundaries, the time constant should be set to zero. Typically, the noise at the boundaries will not be independent from time step to time step (white noise), thus a non-zero time-constant
(coloured noise) is recommended. Please refer to section 11.5 for a
description of the time constants.
11 Decide what additional output is required. Tick the appropriate boxes for HD and/or AD and supply the confidence intervals percentage.
Note that the confidence intervals are found by sorting each of the simulation values in the ensemble at every grid point. The confidence internal of say 90% is found by locating the values in the lowest 5% range of the ensemble and the values in the highest 5% range. Thus, as an absolute minimum the ensemble size must be sufficiently large to represent this fraction. For the 90% case an ensemble size of at least 20
(1/20 = 5%) is required. It is recommended to use a larger ensemble size than the minimum dictated by the confidence interval.
11.8
A step by step guide to updating using the Kalman filter method
If water level, discharge or concentration measurements are available within the model domain these may be utilized for updating the model.
Below follows a step-by-step guide for setting up a model that uses the
Kalman filter updating method.
1 Follow the step-by-step guide for setting up an uncertainty run given in
2 Determine the location of the measurements that are to be utilized for the updating. The location of the measurement is inserted through the
430 MIKE 11
A step by step guide to updating using the Weighting function method use of a river name and a chainage. Remember that the measurements do not need to be located at a cross section.
3 Set the variable type of the measurement. If a concentration measurement is to be used, then the advection dispersion component number is also required.
4 Specify the location of the file holding the measured data by browsing for the file. The data must be in the dfs0 format with a calendar axis.
5 The description used for the standard deviation is to be supplied. The standard deviation may be of three types
– constant, a value is specified in the value/file field
– relative, a percentage is specified in the value/file field
– a time series, a file name and an time series is specified by browsing.
If the relative or the time series option has been selected, bounds can optionally be applied to the standard deviation.
6 Items 3 - 5 are repeated for every measurement. Augmenting the list with a measurement is done by placing the courser in a row in the overview at the bottom of the measurements menu and then subsequently pressing the right tab key until a new row appears.
7 Additionally, the updating method may be used for forecasting by setting a time of forecast within the simulation period specified in the simulation editor. Remember that for each measurement data must be available from simulation start until time of forecast.
8 Finally, the forecast mode should be selected. Either deterministic
(quick, no forecast statistics) or stochastic (slow, but with forecast statistics).
11.9
A step by step guide to updating using the Weighting function method
Below follows a step-by-step guide for setting up a model that uses the
Weighting function updating method.
1 Follow steps 1-5 in the step-by-step guide for setting up an uncertainty
2 Select ‘Measurement update’ and ‘Weighting function’ in the General menu.
Data assimilation editor
431
Data Assimilation editor
3 If forecasting is performed, a time of forecast is set. The time of forecast should be within the simulation period specified in the simulation editor.
4 Determine the location of the measurements that are to utilized for the updating. The location of the measurement is inserted through the use of a river name and a chainage. Remember that the measurements do not need to be located at a cross section.
5 Set the variable type of the measurement. If a concentration measurement is to be used, then the advection dispersion component number is also required.
6 Specify the location of the file holding the measured data by browsing for the file. The data must be in the dfs0 format with a calendar axis.
The measurement data do not need to cover the entire period up to the time of forecast. Updating is simply performed for each measurement up to the time of the last data point in the dfs0 file.
7 Set the type of weighting function, the amplitude of the function in the measurement point and the lower and upper chainages for which the function should be applied. The amplitude should be se to 1 if a perfect match to the measurement is wanted, whereas an amplitude less than 1 should be chosen to account for uncertainties in the measurements. The type of weighting function and the bounds for which it applies should reflect the correlation between the model error at the measurement location and the errors at nearby grid points. Note that the weighting function can only be applied on the branch where the measurement point is located.
8 If error forecasting should be applied, activate the ‘Apply error forecast’ tick box and choose the error forecast model from the pull-down menu. The error forecast models are defined in the Equation editor.
9 Items 4 - 8 are repeated for every measurement. Augmenting the list with a measurement is done by placing the courser in a row in the overview at the bottom of the measurements menu and then subsequently pressing the right tab key until a new row appears.
11.10 Examples
With the installation of MIKE 11 follows a number of examples illustrating the use of the Data assimilations methods.
The examples are all based on a simple set-up with three branches. The examples are designed to illustrate the main features of the data assimilation. The are 5 examples available all located in the folder:
432 MIKE 11
Examples
‘...\examples\m11\DataAssimilation\example1’
There five examples are described below
11.10.1 Uncertainty assessment on hydrodynamic simulation
The example located in the folder ‘uncertainty’ illustrates how an uncertainty assessment simulation is set up. Please run the simulation to generate the results.
Note that confidence intervals are stored in the additional hydrodynamic
result file. Figure 11.10 illustrates the temporal variation of the discharge
through the structure located in Trib2 along with a 90% confidence interval band.
Figure 11.10 The discharge through the structure in Trib2. The upper and lower limits of the 90% confidence interval are also illustrated.
11.10.2 Kalman filter updating on hydrodynamic set-up
Based on the set-up from the example described previously an updating model has been implemented. The full set-up is located in the folder
‘UpdateKalman’. The example illustrates how the Kalman filter is capable
of recreating a lost peak of a hydrograph. Figure 11.11 illustrates the
effectiveness of the updating technique.
Data assimilation editor
433
Data Assimilation editor
Figure 11.11 Updating using the Kalman filtering technique. The discharge at the upstream end of the main stem is illustrated. The blue curve is the result obtained using MIKE 11 without updating the black curve with crosses is the result obtained using the updating method. The updating is based on a measurement located further downstream in the main stem.
11.10.3 Uncertainty assessment on advection dispersion simulation
The example located in the folder ‘AD_uncertainty’ illustrates how an advection dispersion uncertainty assessment simulation is set up.
Figure 11.12 shows the temporal variation of the concentration at the junc-
tion of the main stem and Trib2 along with a 90% confidence interval band.
434 MIKE 11
Examples
Figure 11.12 The concentration at the junction of the main stem and trib2. The upper and lower limits of the 90% confidence interval are also illustrated.
11.10.4 Kalman filter updating on advection dispersion set-up
The advection dispersion set-up from the previous example has modified so that the upstream boundary condition consists of a constant concentration of 0.5 g/m
3
. The present example illustrates how the updating technique also is effective for the transport equation. The set-up is located in
the folder ‘AD_UpdateKalman’. Figure 11.13 illustrates the effectiveness
of the updating technique for AD-simulations.
Data assimilation editor
435
436
Data Assimilation editor
Figure 11.13 The concentration at the junction of the main stem and trib2. The red curve illustrates the original simulation without erroneous boundary condition. The blue curve illustrates the updated results.
Finally for comparison the erroneous results (no update) are illustrated as a horizontal line at 0.5 g/m 3 .
MIKE 11
B A T C H S I M U L A T I O N E D I T O R
437
438 MIKE 11
Setting up a Batch Simulation
12 BATCH SIMULATION EDITOR
The Batch Simulation Editor offers a possibility for setting up a batch simulation from the MIKEZero shell. That is, the Batch Simulation Editor is used to pre-define a number of simulations where all items included in a simulation (input-files, simulation parameters, output files etc.) can be changed from simulation to simulation and multiple simulations will be performed automatically when starting the Batch simulation.
The Batch Simulation Editor has been developed in cooperation with CTI
Engineering, CO., Ltd., Japan.
12.1 Setting up a Batch Simulation
The following steps are necessary to setup the Batch Simulation: z z z
Pre-define base simulation file
Define parameters to adjust in batch simulation
Specify input parameters for each simulation
Each of the steps are described in the following:
Pre-define base simulation file
The Batch Simulation Editor is designed such, that a Base simulation file must be defined with all relevant information concerning models and simulation mode, input files, simulation period, timestep, initial conditions and output file names. Batch simulations will then be performed with this
Sim11-file as a basis and only if other parameters or filenames have been defined by the user in the Batch Simulation Editor, will the definitions in the Base Sim11-file be modified.
Filename and path to the base Sim11 file must be defined in the ‘Base
Simulation File’ field (Use the ‘...’ button to browse for the Base Sim11 file on your computer).
Define parameters to adjust in batch simulation
The user must define the number of simulations to be performed in the batch simulation by specifying a number in the ‘Number of simulations’ field. According to the number defined in this field a number of (empty) rows will be introduced in the ‘Selected Parameters’ grid, see example in
Figure 12.2, where a number of 4 simulations has been chosen.
Batch Simulation Editor
439
Batch Simulation Editor
Each line in the ‘Selected Parameters’ grid must only contain specifications of the parameters or input files which should be different from the base simulation file. Parameters which should differ from the base simulation file is selected in the tree-view on the left-part of the Batch Simula-
tion Editor, see Figure 12.1. Open the tree view items by clicking the ‘+’
and select the item/parameter which should be modified in the batch simulation by double-clicking in the empty square in front of the specific item.
After double-clicking the item, a new column will be introduced in the
‘Selected Parameters’ grid which makes it possible for the user to select different input files or define variations in input parameters.
440
Figure 12.1
Tree view from the Batch Simulation Editor dialog for selecting batch simulation parameters
Specify input parameters for each simulation
Input parameters for the batch simulation can be different input file names, different simulation parameters, activating or deactivating simulation models (e.g. activate and/or deactivate AD-model in some simulations) etc.
If e.g. the Network file should be different in some simulations, open the
‘Input files’ item in the tree-view and double-click the Network square.
After this a Network column is presented in the ‘Selected Parameters’ grid
MIKE 11
Setting up a Batch Simulation and network-files can now be specified in this column - either manually or by pressing the ‘...’ button to browse for the required file. If e.g. the network file in one simulation should be the same as in the base simulation file - but other parameters are changed - the ‘base network file’ must be defined in the network field, as it is not allowed to have any blank cells in the ‘Selected Parameters’ grid.
Additionally, e.g. the AD-model should be deactivated in some simulations, open the ‘Models’ item in the tree-view and double-click the AD square. In the ‘Selected Parameters’ grid you will now have the possibility in the AD column to set the value to False (model deactivated) or True
(Model activated in simulation).
After all files and parameters for the batch simulation have been specified, it is required to save the data to a Batch Simulation file (*.BS11).
The ‘Verify’ button can be used to make a test of all batch-setups in the
Batch Simulation file. The verification procedure includes a test of all input-files, simulation parameters etc. and therefore, if problems exist in some of the input files or other simulation parameters, the user will be informed about this through the verification procedure.
After the verification of the setup has been performed, press the ‘Run’ button to start the batch simulations.
Figure 12.2 shows an example of a Batch Simulation setup, where two dif-
ferent network files are combined with two different HD Parameter files.
A setup like this could be used to investigate the impact of variations in bed resistance values (Manning numbers) at locations where a hydraulic structure (weir) has been planned. The two different network files will then be identical except from the one file will contain description on the new proposed weir, and the two HD Parameter files will only differ in the local variation of the Manning numbers.
Output from the four different batch simulations has also been defined such, that results from each simulation are saved in different result-files.
Batch Simulation Editor
441
Figure 12.2
Example of Batch Simulation setup.
Batch Simulation Editor
442 MIKE 11
F L O W R E S I S T A N C E A N D
V E G E T A T I O N A
443
444 MIKE 11
Flow Channels in Halkær Å
A.1 FLOW RESISTANCE AND VEGETATION
Only a few detailed investigations have been made on establishing relationships between flow resistance in a stream filled with vegetation and flow resistance in the same stream without any vegetation. A quantitative evaluation of the influence of vegetation on flow resistance has been performed in a few Danish gauging programmes. For each of the programmes it has been possible to identify the influence of the weed on the flow resistance, but it has not been possible to transfer the results to other streams and environments. Therefore, it is evident, that description of the weeds influence on flow resistance and hydraulic conditions in general is always a matter of calibrating the modelling system by adjusting values of the bed resistance parameter.
Results and findings from the Danish gauging programmes and investigations on the weeds influence on flow resistance are described in the following.
A.1.1 Flow Channels in Halkær Å
Jensen et. al, /4/ describes experiments performed in a danish stream
named ‘Halkær Å’. A straight-line stretch of the stream with very dense vegetation was chosen for the experiment, and regulators for control of the discharge into the stretch were introduced. The object of the experiment was to determine Q-h relations for different weed densities. Q-h relations were established for natural (very dense) weed conditions, and additionally for situation where flow channels of different widths were cut in the weed. Widths of 0.5 m, 1 m and 2.5 m (equals weed-free conditions) were investigated. The vegetation type was Bur Reed (latin: Sparganium sp.; danish: Pindsvineknop) with few occurrences of Water Thyme (latin: Helodea sp.; danish: Vandpest). The obtained Q-h relations are presented in
Flow Resistance and Vegetation A
445
Flow Resistance and Vegetation
Fig A.1.1
Q-h curves determined for varying flow channel width
Calculated Manning numbers (Manning’s M) are presented in Fig A.1.2 as
a function of Discharge, Q. From this figure, it can be seen, that the flow resistance in a weed-filled stream can be up to 4 times larger compared to weed-free conditions in the same stream.
446
Fig A.1.2
Manning’s M calculated as a function of Discharge, Q
MIKE 11
Laboratory measurements using Bur Reed
A.1.2 Laboratory measurements using Bur Reed
Jensen /3/ describes a laboratory experiment using a 15 m long and 0.3 m
wide flow channel. A weed-bank of 2 meters in length was prepared using leaves of Bur Reed (latin: Sparganium emersum Rehman; danish: enkeltbladet pindsvineknop). The experiment included a series of measurements
with varying weed density. Fig A.1.3 shows the results from the measure-
ments. Manning’s n is plotted against the product; Velocity, V, times the hydraulic radius, R, for two different densities of weed (defined by mass of dry material per area) and a complete weed-free situation. From the results it can be seen, that the flow resistance varies with a factor of 4 to 6 from a weed-free channel to a situation with very dense vegetation (325 g dry material/m
2
).
Fig A.1.3
Manning’s n vs VR (VR: Velocity times Hydraulic Radius)
Jensen /3/ discusses the possible correlation of flow resistance and
hydraulic parameters and presents arguments, stating that the variation in flow resistance can be correlated to the product, VR for a specific weed density by the following equation:
n
= aln VR +
(A.1.1) where, n is Manning’s n, V is the average flow velocity, R hydraulic radius and a and b are coefficients determined by regression. A verification trial
of eq. (A.1.1) using measurements from another danish stream; Simested
Flow Resistance and Vegetation A
447
Flow Resistance and Vegetation
Å, was unsuccessful. Application of eq. (A.1.1) is, however, supported by
Bakry /1/ where statistics have been made on 12 cross sections with
‘drowned weed’, that is, weed which primarily gets its nourishment from the water and therefore is not limited to the area near the stream banks. In this series of investigations it was found, that in case the weed is limited to the banks only it is suitable to use the following expression:
n
=
aD
β
η
(A.1.2)
where a and b are coefficients as described for equation (A.1.1) and D
η the hydraulic depth calculated from:
is
D
η
=
B
(A.1.3) where A is the flow area and B is the width of the section at water surface.
It should be noted, that eq. (A.1.1) depends significantly on the flow
velocity compared to eq. (A.1.2). This reflects the fact, that weed along
banks (non-drowned) is less liable to lie down due to high flow velocities than fully drowned weed.
A.1.3 Experiments in ‘Kimmeslev Møllebæk’
Høybye et. al, /2/ describes how Q-h curves have been determined in a
danish stream named ‘Kimmerslev Møllebæk’ for both a winter and a summer situation. These situations are practically identical to periods with no weed in the stream and periods with very dense vegetation present in the stream. In the summer situation the weed is primarily bank vegetation and to a smaller extent bed vegetation. Bottom width of the cross section is approx. 2 m, bank slopes approx. 30 degrees and measurements have been performed - for both situations - for depths between approx. 6 and 50 cm.
Results showed, that Manning’s M in the winter situation varies from 15 m
1/3
/s at small water depths up to 30 m
1/3
/s for large water depths.
Fig A.1.4 shows the calculated Manning numbers as a function of water
depth. For comparison expressions of the form (A.1.2) have been fitted to
the data.
448 MIKE 11
Experiments in ‘ArnÅ’
Fig A.1.4
Manning’s M for Kimmerslev Møllebæk in summer and winter period. Results calculated with the formulas of the form M =
αD
β
are also included.
A.1.4 Experiments in ‘ArnÅ’
Høybye et al., /2/, describes a gauging programme with the purpose of
determining the variation of Manning’s M in the period from May 1990 till October 1991. In the beginning of the period, Manning’s M is approx.
10 m
1/3
/s, increasing to approx. 15 m
1/3
/s in August 1990 as a result of weed cutting. Thereafter Manning’s M increases during winter to a value of approx. 25 m
1/3
/s. From april it is found, that Manning’s M starts to drop and ends at approx. 10 m
1/3
/s in late summer.
These results - an annual variation in Manning’s M between approx. 10 m
1/3
/s and 25 m
1/3
/s - are identical to the variations observed in ‘Kimmerslev Møllebæk’.
Flow Resistance and Vegetation A
449
Flow Resistance and Vegetation
A.1.5 References
/1/ Bakry, M.F.; T.K.Gates; A.F.Khattab:
“Field Measured Hydraulic Resistance Characteristics in Vegetation
Infested Canals”. Journal of Irrigation and Drainage Engineering.
Vol 118 No. 2, 1992.
/2/ Høybye, J. Alex Andersen:
“Eksperimentel Undersøgelse af Friktionsformler for Åbne
Vandløb”. Hedeselskabet. Afd. for Hydrometri og Vandressourcer,
1996
“Experimental investigations of friction formulae for open channels”. Hedeselskabet, dep. for Hydrometry and Water Resources,
1996 (In Danish)
/3/ Jensen, K.R.:
“Undersøgelse af Vandløbsvegetationens Hydrauliske Indflydelse.”
Afgangsprojekt, AUC, 1992
“Investigation of the influence of stream vegetation on hydraulic conditions” B.Sc. Thesis from University of Aalborg, Denmark (In
Danish)
/4/ Jensen, S.A.B.; Niels Olsen; Jan Pedersen:
“Strømrender i Grødefyldte Vandløb”. Afgangsprojekt, AUC, 1990
“Flow channels in weed-filled streams”. B.Sc. thesis from Univer-
sity of Aalborg, 1990.
450 MIKE 11
A D D I T I O N A L T O O L S B
451
452 MIKE 11
Merging .pfs files
B.1 ADDITIONAL TOOLS
Apart from the catalogue of features which are accessible from the MIKE
Zero interface some additional application tools also come with a MIKE
11 installation. These are: z z z pfsmerge: An application which is used for merging two or more pfs files (.nwk11,.bnd11,.ad11 etc.) m11conv: This tool is used for converting set-ups from v. 3.2 or earlier to the MIKE Zero format.
res11read: A tool for converting result files from mike11 (.res11 files) to text files (ascii).
B.1.1 Merging .pfs files
In some instances it may be necessary to merge set-ups. To do so the pfsmerge.exe program may be used. This program merges two or more files in the pfs format into one. The application may be applied to the following types of files:
– Network files (.nwk11). Please note the feature Number Points
Consecutively (p. 36) under the network editor.
– Boundary files (.bnd11).
– Rainfall-Runoff files (.rr11).
– Hydrodynamic parameter files (.hd11).
– Advection dispersion files (.ad11).
– Water quality files (.wq11).
– Eutrophication editor (.eu11).
– Sediment transport (.st11).
– Flood forecasting files (.ff11).
The application runs in a dos prompt and has the following syntax:
...\PFSMERGE pfsfile1 ... pfsfileN pfsfiletotal where
...\ denotes the full path to the application located in the bin director of the installation.
Additional Tools B
453
Additional Tools pfsfile1 ... pfsfileN: The list of files to merge.
pfsfiletotal: The name of the combined pfsfile.
Note that the above syntax is based on a call from the data directory
(the directory where the pfsfiles are located).
B.1.2 Converting set-ups from v. 3.2 and prior
m11conv is an application which is only for use when converting set-ups from v.3.2 and earlier to the present format. This facility is launched from the MIKE 11 menu under Start -> Programs ->MIKE 11 -> Mike 11 convert. The start up window has one pull down menu File which lists a number of conversion possibilities. Choose the appropriate format conversion and browse the file to be converted.
Note: When converting v.3.2 network-files (.RDF) all relevant cross sec-
tion files (.pst, .ix0, .ix1) must be located in the same directory as the
.RDF file.
B.1.3 Converting simulation results to text files
The application res11read is designed for converting one or more MIKE
11 result files to a text file (ascii). Thus the tool may be used as a conversion tool for subsequent post-processing of the results.
As for ‘pfsmerge’ the application is launched from a dos prompt. The syntax is:
...\RES11READ Option(s) Res11FileName1 ... Res11FileNameN OutputFileName where
...\ denotes the full path to the application located in the bin director of the installation.
Res11FileName1 ... Res11FileNameN is the list of .res11 files to convert.
OutputFileName is the name of the output file (ascii).
Finally one or more of the options below should be used:
454 MIKE 11
Converting simulation results to text files
– xy: X-Y coordinates and levels for all grid points.
– xyh: X-Y coordinates and levels for all h-points.
– xyq: X-Y coordinates and levels for all Q-points.
– xyxsec: X-Y coordinates and levels for all h-points with cross sections.
– raw: Raw data for cross sections.
– sim: Content of the .sim11 file used for the simulation.
– minX: Minimum values in grid points for item no X.
– maxX: Maximum values in grid points for item no X.
– xsecids: Cross section IDs.
– usermarks: User defined marks.
– items: List of dynamic items.
– allres: All results of the simulation.
– someresFILE: Some results are written to the output file (selection in FILE).
– compareFILE: Compare results (selection in FILE).
– silent: Writing to prompt is cancelled. Used in conjunction with one or more of the other options.
– MessageFILE: Return file with 0 or 1 for Compare results (Returning FILE).
– DHIASCII: Additional option for suppressing header information - in DHI standard format. Should be used in conjunction with one or more of the above.
– FloodWatch: Flood Watch comma separated Matrix format.
For the option someresFILE the format of the FILE is:
Figure 12.3
Format for use in the file used for the someresFILE option.
Additional Tools B
455
Additional Tools
Note that the file has a header line at the start. An additional option is available to redirect individual selections to additional text files. This can be done using the ">" character at the end of a line in FILE:
Figure 12.4
Format of file used for the someresFILE option, with alternate output file option.
456 MIKE 11
I N D E X
457
A
. . . . . . . . . . . . . . . . . 348
Advanced cohesive sediment transport module
Advection-dispersion
B
. . . . . . . . . . . . . . . . 43
. . . . . . . . . . . . . . . . . 65
C
Cohesive sediment transport module .
341
Control Structures
. . . . . . . . . . . . . . 89
. . . . . . . . . . . . . . 178
Cross section
. . . . . . . . . . . . . . 163
. . . . . . . . . . . . . . 153
. . . . . . . . . . . . . . . 172
. . . . . . . . . . . . . . . . 177
. . . . . . . . . . . . . . . . . 60
. . . . . . . . . . . . . . . 61
. . . . . . . . . . . . . . . . 61
D
. . . . . . . . . . . . . . . 120
. . . . . . . . . . . . . . 117
. . . . . . . . . . . . . . . 323
. . . . . . . . . . . . . . . 352
. . . . . . . . . . . . . . . 131
E
F
. . . . . . . . . . . . . . . . 32
File import
G
H
. . . . . . . . . . . . . . . . . . 25
I
. . . . . . . . . . . . . . . 347
. . . . . . . . . . . . . . . 19
Import File
458 MIKE 11
. . . . . . . . . . . . . . . . 19
J
. . . . . . . . . . . . . . . . . 50
K
L
. . . . . . . . . . . . . . 44
M
. . . . . . . . . . . . . . . . . . 322
. . . . . . . . . . . . . . . 136
. . . . . . . . . . . . . . . 18
N
. . . . . . . . . . . . . . 31
Non-cohesive sediment transport
P
. . . . . . . . . . . . . . . . . . 63
Q
R
. . . . . . . . . . . . . . . 91
. . . . . . . . . . . . . . 326
. . . . . . . . . . . . . . . . . 127
. . . . . . . . . . . . . . 135
S
. . . . . . . . . . . . . . . 328
Sediment
Single layer cohesive component
Simulation
. . . . . . . . . . . . . . . . 17
. . . . . . . . . . . . . . . . 18
. . . . . . . . . . . . . . . . . 149
T
The advection-dispersion equation
Time step
. . . . . . . . . . . . . . 24
. . . . . . . . . . . . . . . . 145
U
W
. . . . . . . . . . . . . . . . . . 55
. . . . . . . . . . . . . . . 56
. . . . . . . . . . . . . . 56
. . . . . . . . . . . . . . . . . . 303
459
460 MIKE 11
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