MIKE 11

MIKE 11

A modelling system for Rivers and Channels

User Guide

DHI Software 2003

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'.

Limited Liability

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

June 2003

Edition 2003

5

6 MIKE 11

MIKE 11 1

Simulation Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1 SIMULATION EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1.1

Models

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1.1.1

Models

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.1.2

Simulation Mode

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

1.2

Input

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

1.3

Simulation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.3.1

Simulation Period

. . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.3.2

Initial Conditions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

1.4

Results

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.5

Start

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

River Network Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2 RIVER NETWORK EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.1

Graphical View

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.1.1

File

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.1.2

View

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.1.3

Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.1.4

Layers

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2.1.5

Settings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.2

Tabular view: Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2.2.1

Points

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2.2.2

Branches

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

2.2.3

Alignment Lines

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

2.2.4

Junctions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

2.3

Tabular view: Structures

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

2.3.1

Weirs

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.3.2

Culverts

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

2.3.3

Pumps

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

2.3.4

Bridges

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

2.3.5

Regulating

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

2.3.6

Control Str.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

2.3.7

Dambreak Str.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

2.3.8

Dambreak Erosion

. . . . . . . . . . . . . . . . . . . . . . . . . . 107

2.3.9

User Defined Structure

. . . . . . . . . . . . . . . . . . . . . . . 110

2.3.10 Tabulated Structure

. . . . . . . . . . . . . . . . . . . . . . . . . 111

2.3.11 Energy Loss

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

2.4

Tabular view: Routing

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

7

2.4.1

Channel routing

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

2.4.2

Flood control Q and Q-rate

. . . . . . . . . . . . . . . . . . . . . . 117

2.4.3

Flood control H-Q / H-V curve

. . . . . . . . . . . . . . . . . . . . 118

2.4.4

Flood control by orifice

. . . . . . . . . . . . . . . . . . . . . . . . 119

2.4.5

Diversions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

2.4.6

Kinematic Routing Method

. . . . . . . . . . . . . . . . . . . . . . 121

2.5

Tabular view: Runoff / groundwater links

. . . . . . . . . . . . . . . . . . 123

2.5.1

MIKE SHE links

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

2.5.2

Rainfall-runoff links

. . . . . . . . . . . . . . . . . . . . . . . . . . 130

2.6

Tabular View: Grid Points

. . . . . . . . . . . . . . . . . . . . . . . . . . . 131

2.7

Tool bars

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

2.7.1

Tool Bar for River Network

. . . . . . . . . . . . . . . . . . . . . . 133

2.7.2

Tool Bar for Alignment Lines

. . . . . . . . . . . . . . . . . . . . . 136

Cross Section Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

3 CROSS SECTION EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

3.1

Raw data View

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

3.1.1

Dialog boxes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

3.1.2

Tabular view

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

3.1.3

The Cross section pull down menu

. . . . . . . . . . . . . . . . . 153

3.1.4

Graphical Settings

. . . . . . . . . . . . . . . . . . . . . . . . . . . 154

3.1.5

Miscellaneous settings

. . . . . . . . . . . . . . . . . . . . . . . . 155

3.1.6

Update Markers settings

. . . . . . . . . . . . . . . . . . . . . . . 155

3.2

Processed data view

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

3.2.1

Tabular View

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

3.3

Importing cross sections using File Import

. . . . . . . . . . . . . . . . . . 158

3.3.1

Import Raw Data

. . . . . . . . . . . . . . . . . . . . . . . . . . . 158

3.3.2

Import Processed Data

. . . . . . . . . . . . . . . . . . . . . . . . 162

3.3.3

Import Coordinates of Levee Marks

. . . . . . . . . . . . . . . . 163

3.4

Exporting cross sections using File Export

. . . . . . . . . . . . . . . . . 163

3.5

Selecting Cross Sections

. . . . . . . . . . . . . . . . . . . . . . . . . . . 164

3.6

Plotting Multiple Cross Sections

. . . . . . . . . . . . . . . . . . . . . . . 164

Boundary Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

4 BOUNDARY EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

4.1

Users Upgrading from MIKE 11 Version 2002 or Previous Versions

. . . 169

4.2

Overview of the Boundary File

. . . . . . . . . . . . . . . . . . . . . . . . 170

4.2.1

The Boundary Table - Upper Split Window

. . . . . . . . . . . . 170

4.2.2

Specifying the Boundary Description

. . . . . . . . . . . . . . . . 172

4.2.3

Specifying the Boundary Type, Data Type and File/Values

. . . 176

8 MIKE 11

4.3

Tools

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

4.3.1

Quick set up of Graded Sediment Boundaries

. . . . . . . . . . 192

4.3.2

Quick set up of AD Boundaries

. . . . . . . . . . . . . . . . . . 193

4.3.3

Copying Point Source Boundaries

. . . . . . . . . . . . . . . . . 194

4.3.4

Scale factor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Rainfall-Runoff Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

5 RAINFALL-RUNOFF EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

5.1

Specifying model Catchments

. . . . . . . . . . . . . . . . . . . . . . . . 203

5.2

The NAM Rainfall-runoff model

. . . . . . . . . . . . . . . . . . . . . . . 205

5.2.1

Surface-rootzone

. . . . . . . . . . . . . . . . . . . . . . . . . . 206

5.2.2

Ground Water

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

5.2.3

Snow Melt

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

5.2.4

Irrigation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

5.2.5

Initial conditions

. . . . . . . . . . . . . . . . . . . . . . . . . . . 216

5.2.6

Autocalibration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

5.3

UHM

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

5.4

SMAP

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

5.5

Urban

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

5.5.1

Introduction

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

5.5.2

Urban, model A, Time/area Method

. . . . . . . . . . . . . . . . 225

5.5.3

Urban, model B, Time/area Method

. . . . . . . . . . . . . . . . 227

5.5.4

Additional Time series

. . . . . . . . . . . . . . . . . . . . . . . 230

5.6

Flood Estimation Handbook (FEH)

. . . . . . . . . . . . . . . . . . . . . 231

5.6.1

Background

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

5.6.2

Methods for hydrograph Generation

. . . . . . . . . . . . . . . 231

5.6.3

T-Year Event

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

5.6.4

Probable Maximum Flood

. . . . . . . . . . . . . . . . . . . . . 236

5.6.5

Generation of an Observed Flood Event

. . . . . . . . . . . . . 238

5.6.6

Results

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

5.6.7

Validation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

5.6.8

Log Files

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

5.7

DRiFt

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

5.7.1

Surface flow

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

5.7.2

Initial conditions

. . . . . . . . . . . . . . . . . . . . . . . . . . . 242

5.7.3

Rainfall

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243

5.8

Time Series

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246

5.9

Parameters menu

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

5.9.1

Enlargement ratio

. . . . . . . . . . . . . . . . . . . . . . . . . . 250

5.9.2

Loss Parameters

. . . . . . . . . . . . . . . . . . . . . . . . . . . 250

5.9.3

Land use definitions for QLSF method

. . . . . . . . . . . . . . 250

9

5.9.4

Default values for specific method

. . . . . . . . . . . . . . . . . 250

5.9.5

Time-fixed combinations

. . . . . . . . . . . . . . . . . . . . . . . 251

5.9.6

MAW merged output file.

. . . . . . . . . . . . . . . . . . . . . . . 251

5.10 Basin View

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251

5.10.1 Activating the Basin View

. . . . . . . . . . . . . . . . . . . . . . 251

5.10.2 Importing Layers

. . . . . . . . . . . . . . . . . . . . . . . . . . . 252

5.10.3 Basin Work Area

. . . . . . . . . . . . . . . . . . . . . . . . . . . 252

5.10.4 Preparing Catchments

. . . . . . . . . . . . . . . . . . . . . . . . 257

5.10.5 Inserting Rainfall Stations

. . . . . . . . . . . . . . . . . . . . . . 257

5.10.6 Preparing Thiessen weights

. . . . . . . . . . . . . . . . . . . . . 258

5.11 Result Presentation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

5.12 A Step-by-step procedure for using the RR-Editor

. . . . . . . . . . . . . 262

Hydrodynamic Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

6 HYDRODYNAMIC EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

6.1

Quasi Steady

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

6.1.1

Computational parameters

. . . . . . . . . . . . . . . . . . . . . . 268

6.1.2

Steady state options

. . . . . . . . . . . . . . . . . . . . . . . . . 269

6.1.3

Contraction and expansion loss coefficients

. . . . . . . . . . . . 270

6.2

Reach Lengths

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270

6.3

Add. Output

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

6.3.1

Additional output for QSS with vegetation

. . . . . . . . . . . . . 274

6.4

Flood Plain Resistance

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

6.5

Initial

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

6.6

Wind

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

6.7

Bed Resistance

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

6.7.1

Uniform approach

. . . . . . . . . . . . . . . . . . . . . . . . . . . 278

6.7.2

Triple zone approach

. . . . . . . . . . . . . . . . . . . . . . . . . 279

6.7.3

Vegetation and bed resistance

. . . . . . . . . . . . . . . . . . . 280

6.8

Bed Resistance Toolbox

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

6.9

Wave Approx

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

6.9.1

Fully Dynamic and High Order Fully Dynamic

. . . . . . . . . . . 283

6.9.2

Diffusive Wave

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

6.9.3

Kinematic Wave

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

6.10 Default values

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

6.10.1 Computation Scheme

. . . . . . . . . . . . . . . . . . . . . . . . . 285

6.10.2 Switches

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286

6.11 User Def. Marks

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286

6.11.1 Activation of Bed resistance Triple Zone Approach

. . . . . . . . 287

6.12 Encroachment

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

10 MIKE 11

6.12.1 Iteration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

6.12.2 Location

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

6.12.3 Encroachment method

. . . . . . . . . . . . . . . . . . . . . . . 289

6.12.4 Encroachment positions

. . . . . . . . . . . . . . . . . . . . . . 290

6.12.5 Reduction parameters (only encroachment methods 3 to 5)

. . 291

6.12.6 Target Values

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 291

6.12.7 Encroachment simulation overview

. . . . . . . . . . . . . . . . 292

6.12.8 Encroachment station overview

. . . . . . . . . . . . . . . . . . 292

6.12.9 General guide lines for carrying out encroachment simulations

293

6.13 Mixing Coefficients

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

6.13.1 Water & Water

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

6.13.2 Location

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

6.13.3 Water & Vegetation

. . . . . . . . . . . . . . . . . . . . . . . . . 294

6.14 W. L. Incr.- Curve

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

6.14.1 General

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

6.14.2 System Definition

. . . . . . . . . . . . . . . . . . . . . . . . . . 296

6.14.3 Tabular view

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296

6.15 W. L. Incr.- Sand Bars

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

6.15.1 General

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

6.15.2 System Definition

. . . . . . . . . . . . . . . . . . . . . . . . . . 298

6.15.3 Tabular view

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298

6.16 Heat Balance

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298

6.17 Stratification

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300

Advection-Dispersion Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

7 ADVECTION-DISPERSION EDITOR

. . . . . . . . . . . . . . . . . . . . . . . 307

7.0.1

Advection-Dispersion module (AD)

. . . . . . . . . . . . . . . . 307

7.0.2

Water Quality module (WQ)

. . . . . . . . . . . . . . . . . . . . 307

7.0.3

Cohesive Sediment Transport module (CST)

. . . . . . . . . . 307

7.0.4

Advanced Cohesive Sediment Transport module (A CST)

. . . 308

7.0.5

The Advection-Dispersion Equation

. . . . . . . . . . . . . . . . 308

7.1

Sediment layers

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310

7.1.1

Single layer cohesive component.

. . . . . . . . . . . . . . . . . 311

7.2

Non-cohesive ST

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312

7.3

Ice model

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313

7.4

Additional output

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

7.5

Components

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316

7.6

Dispersion

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318

7.7

Init. cond.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320

7.8

Decay

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323

7.9

Cohesive ST

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324

11

7.9.1

Single Layer Cohesive Model

. . . . . . . . . . . . . . . . . . . . 325

7.9.2

Multi Layer Cohesive Model

. . . . . . . . . . . . . . . . . . . . . 327

7.9.3

Description

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

WQ EcO Lab Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333

8 WQ ECO LAB EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335

8.1

Model Definition

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335

8.2

State Variables

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336

8.3

Constants

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

8.4

Forcings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

8.5

Auxiliary Variables

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

8.6

Processes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

8.7

Derived Output

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340

WQ (BOD/DO) Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

9 WQ (BOD/DO) EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343

9.1

Level for Water Quality Modelling

. . . . . . . . . . . . . . . . . . . . . . . 343

9.2

Model Level

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343

9.3

Arrhenius

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344

9.4

Degradation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345

9.5

Degradation at the bed (levels 5 and 6)

. . . . . . . . . . . . . . . . . . . 345

9.6

Bed/sediment (levels 2 and 4)

. . . . . . . . . . . . . . . . . . . . . . . . . 346

9.7

Bed / Sediment (Model Levels 5 and 6)

. . . . . . . . . . . . . . . . . . . 347

9.8

Nitrogen Contents (Model Levels 3 and 4)

. . . . . . . . . . . . . . . . . . 347

9.9

Nitrogen Contents (Model Level 6)

. . . . . . . . . . . . . . . . . . . . . . 348

9.10 Nitrification

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350

9.11 Denitrification

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350

9.12 Coliforms

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351

9.13 Phosphorus Content (Model Levels 1 to 4)

. . . . . . . . . . . . . . . . . 352

9.14 Phosphorus Content (Model Levels 5 and 6)

. . . . . . . . . . . . . . . . 353

9.15 Phosphorus Processes in the Water Phase

. . . . . . . . . . . . . . . . . 353

9.16 P. exchange with the bed

. . . . . . . . . . . . . . . . . . . . . . . . . . . 354

9.17 Temperature

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

9.18 Oxygen processes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

9.19 Degradation in the water phase

. . . . . . . . . . . . . . . . . . . . . . . . 358

9.20 Reaeration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

9.21 Non point pollution interface

. . . . . . . . . . . . . . . . . . . . . . . . . . 361

9.22 WETLAND

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

12 MIKE 11

9.22.1 Introduction

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

9.22.2 Integration with WQ

. . . . . . . . . . . . . . . . . . . . . . . . . 362

9.22.3 The Model

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363

9.23 Wetland General

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365

9.24 Wetland Nitrogen

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

9.25 Wetland Phosphorus

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367

9.26 Wetland Components

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368

Sediment Transport Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371

10 SEDIMENT TRANSPORT EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . 373

10.0.1 Sediment transport simulations; Simulation mode

. . . . . . . . 373

10.0.2 The transport models

. . . . . . . . . . . . . . . . . . . . . . . . 374

10.1 Sediment grain diameter

. . . . . . . . . . . . . . . . . . . . . . . . . . . 375

10.2 Transport model

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376

10.2.1 Model Parameters

. . . . . . . . . . . . . . . . . . . . . . . . . . 377

10.2.2 Special features for specific transport models

. . . . . . . . . . 380

10.2.3 Bottom level update methods

. . . . . . . . . . . . . . . . . . . 381

10.3 Calibration factors

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382

10.4 Data for graded ST

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382

10.5 Preset distribution of sediment in nodes

. . . . . . . . . . . . . . . . . . 384

10.6 Passive branches

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384

10.7 Initial dune dimensions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 385

10.8 Non-Scouring Bed Level

. . . . . . . . . . . . . . . . . . . . . . . . . . . 386

Flood Forecasting Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389

11 FLOOD FORECASTING EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . 391

11.1 Basic definitions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391

11.1.1 Simulation Period and Time of Forecast

. . . . . . . . . . . . . 391

11.1.2 Simulation Mode

. . . . . . . . . . . . . . . . . . . . . . . . . . . 391

11.2 Forecast

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393

11.2.1 Forecast length

. . . . . . . . . . . . . . . . . . . . . . . . . . . 393

11.2.2 Include updating

. . . . . . . . . . . . . . . . . . . . . . . . . . . 393

11.2.3 Accuracy

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393

11.2.4 Alternative Modes

. . . . . . . . . . . . . . . . . . . . . . . . . . 394

11.2.5 Location of forecast stations

. . . . . . . . . . . . . . . . . . . . 395

11.3 Boundary estimates

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396

11.3.1 Setup

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397

11.3.2 Editing

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398

11.3.3 Boundary data manipulation

. . . . . . . . . . . . . . . . . . . . 398

13

11.3.4 Storing of Estimated boundaries

. . . . . . . . . . . . . . . . . . 401

11.4 Update specifications

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402

11.4.1 Comparison

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403

11.4.2 Correction

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404

11.4.3 Parameters

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405

11.5 Rating curves

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405

Batch Simulation Editor

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

12 BATCH SIMULATION EDITOR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 409

12.1 Setting up a Batch Simulation

. . . . . . . . . . . . . . . . . . . . . . . . . 409

Appendix A

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413

A.1 FLOW RESISTANCE AND VEGETATION

. . . . . . . . . . . . . . . . . . . . . 415

A.1.1 Flow Channels in Halkær Å

. . . . . . . . . . . . . . . . . . . . . . . . . . 415

A.1.2 Laboratory measurements using Bur Reed

. . . . . . . . . . . . . . . . . 417

A.1.3 Experiments in ‘Kimmeslev Møllebæk’

. . . . . . . . . . . . . . . . . . . . 418

A.1.4 Experiments in ‘ArnÅ’

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419

A.1.5 References

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420

Appendix B

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421

B.1 ADDITIONAL TOOLS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423

B.1.1 Merging .pfs files

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423

B.1.2 Converting set-ups from v. 3.2 and prior

. . . . . . . . . . . . . . . . . . . 424

B.1.3 Converting simulation results to text files

. . . . . . . . . . . . . . . . . . 424

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.

This page is used to define the simulation models to execute and the simulation mode (unsteady or quasi steady).

17

Simulation Editor

1.1.1

Models

The following abbreviations of module names are used:

HD Hydrodynamic

AD Advection-Dispersion

ST Sediment Transport

WQ Water Quality

RR Rainfall-Runoff

FF Flood Forecast

When 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.

In conjunction with selection of a water quality model a selection boxes become active: z

Selection of WQ model:

– BOD/DO: Biological Oxygen Demand/Dissolved Oxygen.

– ECO Lab: ECO Lab water quality modelling.

Furhter a selection box becomes active in the the Biological Oxygen

Demand/Dissolved Oxygen is selected. The selection box offers a number of integratio methods.

z

Integration method.

– RKQC: Fifth order Runge-Kutta with Quality Control.

– RK4: Fourth order Runge-Kutta.

– EULER: Euler or linear solution.

In case ECO Lab modelling is specified the integration method is specified in the Milke 11 ECO Lab editor.

18 MIKE 11

Input

1.1.2

Simulation Mode

Unsteady

The HD calculations are based on hydrodynamic flow conditions.

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.

1.2

Input

Simulation Editor

Figure 1.2

The Input tab.

19

Simulation Editor

Based on the model selection from the Models Property Page 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.

Note that the files required are indicated by the active fields. Two exceptions are the fields for the result files. A hydrodynamic result file is required if z a stand alone Advection-Dispersion/Sediment transport simulation is to be carried out 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 is only required if the hydrodynamic and rainfall model are to run uncoupled.

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

Figure 1.3

The Simulation tab.

MIKE 11

Simulation

1.3.1

Simulation Period

Time step type

Time stepping 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 sepcified in the editable text with heading time step and the unit is given in the unit selection list.

In case the time stepping type is specified as tabulated the time steps are specified by activating the settings button and specifying a time series file

in the dialog included in Figure 1.4.

Figure 1.4

Dialog for specification of the tabulated time step time series file.

The settings for time step adaptation is similarly specified in a menu acti-

vated by the Settings button. The menu is included as Figure 1.5.

Simulation Editor

Figure 1.5

Time step settings for adaptive time stepping.

Minimum/maximum/unit

Defines the limits for the adaptation of the time step.

21

22

Simulation Editor

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 z z z 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 ths 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.

|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.

MIKE 11

Simulation

Simulation Editor z z

|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 solvig 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.

|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.

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.

23

Simulation Editor

1.3.2

Initial Conditions

For each of the modules HD, AD, ST and RR the following can be specified:

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. 276)

Property Page of the Hydrodynamic Editor (p. 267) 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.

24 MIKE 11

Results

1.4

Results

Simulation Editor

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 Freq.

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, demands that the the specified storring time frequency is a multiplum of the time step.

25

Simulation Editor

1.5

Start

26

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 will be reported in a separate window.

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. If any errors or warnings are encountered during simulation the user is given the choice of viewing these at the end of the simulation.

Upon completion the simulation results can be viewed using MIKE View.

MIKE 11

R I V E R N E T W O R K E D I T O R

27

28 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.

This includes:

– Digitising river networks and branch connections.

– Definition of hydraulic structures (weirs, culverts etc.).

– Definition of catchment inflow points (for rainfall run-off model).

2 Overview of all model information in the current simulation.

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

(p. 17).

NOTE: Cross sections are edited using the River Cross Section Editor

(p. 143), 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

29

River Network Editor

Example of insertion of a Catchment link using the Pop-Up menu is

shown in Figure 2.1

Figure 2.1

Illustration of right mouse pop up menu from where all data editors can be accessed.

2.1.1

File

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

30 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

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

31

River Network Editor

32

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

Graphics (p. 35).

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

Graphics (p. 35).

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

view see Graphics (p. 35).

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

view see Graphics (p. 35).

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

view see Graphics (p. 35).

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

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.

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

(p. 37).

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 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.

River Network Editor

33

River Network Editor

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. 37).

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. 423)) 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

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 right corner respectively. This can be changed using the item “Properties...” in the Layers menu.

34 MIKE 11

Graphical View

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

Network

The network settings dialog contains the following property pages: z z z z

Graphics

Mouse

Network data

Select and edit

Graphics

River Network Editor

Figure 2.6

The Graphics property page.

This property page controls the layout of the graphics.

35

River Network Editor

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

36

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.

37

River Network Editor

Note the grid spacing used for snapping is not shown.

– 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

Figure 2.9

38

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

shown in Figure 2.11.

River Network Editor

39

River Network Editor

40

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.

MIKE 11

Tabular view: Network

Overview

An overview of the points is given in this box.

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.

River Network Editor

41

42

River Network Editor

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.

Maximum dx

Maximum distance between to adjacent h-points. See Tabular View: Grid

Points (p. 131)

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.

– Routing: No cross sections are required. Only the flow is calculated,

no water levels. See section 2.4 Tabular view: Routing (p. 114).

– 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.

MIKE 11

Tabular view: Network

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.

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

43

River Network Editor used to avoid zero storage at nodal points to which only link channels and no regular channels are connected.

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.

44 MIKE 11

Tabular view: Network

– Vegetation height.

– Angle between cross section and direction of flow/branch.

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

45

River Network Editor

46

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.

MIKE 11

Tabular view: Network

– 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.

Figure 2.15

Definition of dead water zone along bank.

River Network Editor

47

48

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. 136)). 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.

Once the alignment data are added, the information is ready to be transferred to the cross section editor.

MIKE 11

Tabular view: Network

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.

River Network Editor

Figure 2.18

The Junctions dialog.

49

River Network Editor

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

A number of structures such as weirs, culverts, bridges etc. may be implemented in a simulation. Structures, except pumps with external outlet, are situated at Q-points. The flow over most of the structures is modelled using the energy equation so that local head losses can be incorporated.

The effect of the bed-friction is not taken into account thus it is recommended that the h-points up- and downstream are situated close to the structure.

50 MIKE 11

Tabular view: Structures

2.3.1

Weirs

River Network Editor

Figure 2.19

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.

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.

Weir Formula 1: A standard weir expression is applied. See the

Reference Manual, Weir Formula 1 (p. 178).

51

52

River Network Editor

Weir Formula 2 (Honma): The Honma weir expression is applied.

See the Reference Manual, Weir Formula 2 (Honma) (p. 178).

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. 41).

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 2.20

The weir property page, formula 1.

Width: Width of the flow.

Height: Weir height. See Figure 2.22

Weir Coeff.: Multiplication coefficient in the weir formula.

Weir Exp.: Exponential coefficient in the weir formula.

Invert Level: Bottom datum level. See Figure 2.22

53

River Network Editor

Weir formula 2 Parameters (only weir formula 2 (Honma))

54

Figure 2.21

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 2.22

MIKE 11

Tabular view: Structures

River Network Editor

Figure 2.22

Definition sketch for Weir formula.

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. 42)) 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.

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!

55

2.3.2

Culverts

River Network Editor

56

Figure 2.23

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.

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.

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.

MIKE 11

Tabular view: Structures

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.

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. 41).

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. 42)) defined for the branch in

question. The Q/h relation can not be calculated unless the cross sections

River Network Editor

57

58

River Network Editor 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 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.

MIKE 11

Tabular view: Structures

2.3.3

Pumps

River Network Editor

Figure 2.24

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.

59

60

River Network Editor

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.

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 2.25

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).

2.3.4Bridges

Eight types of bridges may be implemented:

1 FHWA WSPRO bridge method.

2 USBPR bridge method.

3 Fully submerged bridge.

4 Arch Bridge (Biery and Delleur).

5 Arch Bridge (Hydraulic Research (HR)).

6 Bridge piers (D’Aubuisson’s formula).

7 Bridge piers (Nagler).

8 Bridge piers (Yarnell).

River Network Editor

61

62

River Network Editor

It is possible to combine the free surface bridge flow with submerged and overflow solutions - except for Fully submerged bridge and Bridge piers

(D’Aubuisson’s formula).

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 trouble shooting, consult the reference manual ’Trouble shooting for bridge structures’.

Submergence methods:

1 FHWA WSPRO.

2 MIKE11 Culvert.

Overflow methods:

1 FHWA WSPRO.

2 MIKE11 weir.

Name: The river name.

Chainage: The location on the river (not in a point where a cross section is specified).

Bridge ID: String identification of the bridge.

Method: Type of bridge.

Options: Checkboxes for options available for the chosen method.

Geometry and Loss factors: Edit button for entering geometric and loss factor options. Detail button for entering loss coefficient tables.

Graphic: Not available in present release.

Submergence: (Pressure flow) Available if Submergence checkbox is marked (See Options). The user must select method, FHWA

WSPRO or MIKE 11 culvert. For details on FHWA WSPRO see

Submergence, FHWA WSPRO.

MIKE 11

Tabular view: Structures

– Culvert no: When choosing MIKE 11 culvert details of the culvert

structure are in the culvert menu (See section 2.3.2). Culvert no is

chosen as the number marked in the overview box in the culvert menu.

– Bridge level (bottom): Vertical level for the bottom of the girders.

Overflow: Available if Overflow and Submergence checkbox is marked (See options). Selection of FHWA WSPRO or MIKE 11

weir method. For details on FHWA WSPRO see Overflow, FHWA

WSPRO.

– Weir no: When choosing MIKE 11 weir details of the weir structure

are in the weir menu (See section 2.3.1). Weir no is chosen as the

number marked in the overview box in the weir menu.

River Network Editor

Figure 2.26

Overview, Branch2 has three bridge openings - 2, 3 and 4. Marked in the right part of the overview window.

– Overview: Left part show River name, Chainage and Bridge ID.

Right part show methods for the bridge openings.

63

64

River Network Editor

– Multiple waterway openings: If working with multiple waterway openings all multiple waterway openings are marked when the

bridge is activated. (See Figure 2.26). In order to ad additional

openings, mark a row in the right part of the overview window and press insert on the keyboard.

Working with Loss factor tables:

Loss / adjustment factor tables are viewed by pressing the Details buttons.

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 more lines.

FHWA WSPRO & USPBR Bridge

The FHWA WSPRO and the USPBR methods describe free surface flow through a bridge opening. The methods use the up and down stream cross sections inserted in the cross section editor. It is recommended that the distance between the bridge and the cross sections are one opening width (see

Figure 2.27).

MIKE 11

Tabular view: Structures

River Network Editor

Figure 2.27

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

– Overflow

– Skewness, Used when the embankments is not perpendicular to the approaching flow.

65

River Network Editor

– 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:

66

Figure 2.28

Geometry property page.

Opening type: (see definition sketch Figure 2.29 - Figure 2.32).

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 for witch the Waterway length is measured.

River Network Editor

Figure 2.29

Definition sketch of type I opening, vertical embankments and vertical abutments, with or without wingwalls (after Matthai).

Figure 2.30

Definition sketch of type II opening, sloping embankments without wingwalls (after Matthai).

67

River Network Editor

Figure 2.31

Definition sketch of type III opening, sloping embankments and sloping abutments (spillthrough) (after Matthai).

68

Figure 2.32

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 2.27).

– 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 2.27) are

placed correct in respect to the x-values.

– Z: Vertical level of the cross section point.

MIKE 11

Tabular view: Structures

– Resistance: Additional resistance in the cross section point. 1 is resistance corresponding to the manning number.

– Marker: Define the abutments (See Figure 2.33).

River Network Editor

Figure 2.33

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 2.26). 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 2.34)

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 2.27. 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.

69

70

River Network Editor

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 2.27. 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.

Figure 2.34

Multiple openings and stagnation points.

Loss factor:

MIKE 11

Tabular view: Structures

Figure 2.35

Loss factor property page

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.

71

72

River Network Editor

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.

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 2.33).

Between markers 4 and 5 the bed resistance given in the HD editor will be used.

Loss factor tables for FHWA WSPRO:

MIKE 11

Tabular view: Structures

River Network Editor

Table 2.1

Table

I

Opening

Type

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

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

Spur dike #1

Spur dike #2

Spur dike #2

k j

= 0,1

k j

= 0,1

k j k d k d k a k b

,

k

I

II, III and IV

I, II, III and

IV

m

or

M m

or

k j

= 0,1

I, II and IV

m

or

M

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:

73

74

River Network Editor

m

Channel contraction ratio.

M

Bridge opening ratio.

Bridge waterway flow length.

L b

Bridge opening length.

F

3

Froude number in downstream bridge section.

(

Y a

+

Y b

Average water level in bridge section.

x

Unwetted abutment length.

e

Eccentricity.

Portion of waterway blocked by piers/piles.

j

L d

Spur dike length.

Loss factor tables for USBPR:

Table 2.2

Table

Base coefficient

Velocity distribution coefficient

Eccentricity

Skewness

Piers

k

α

2

Function of:

M

or

m

M

or

m

α

1

e M

or

m

k

k M m

k M

or

m

In the Loss Factor menu the user can choose to use

m

or as axis in the tables.

Where:

M m

Bridge opening ratio.

Channel contraction ratio.

MIKE 11

Tabular view: Structures

e

α

1

Degree of eccentricity.

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 2.36 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.

River Network Editor

Figure 2.36

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.

75

River Network Editor

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 describes free surface flow trough an arch bridge opening.

Available options for Arch Bridge:

– Submergence

– Overflow

Geometry and loss factors are viewed by pressing the Edit button under

Geometry and Loss factors.

Figure 2.37

Arch Bridge Geometry property page.

76

Figure 2.38

Arch Bridge Loss factor property page.

Opening width, b: Opening width at the Arch spring line.

MIKE 11

Tabular view: Structures

– 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.

Figure 2.39

Hydraulic variables for Arch Bridge.

Loss factor tables for arch bridges:

Biery and Delleur: Coefficient of discharge,

C

D

is a function of or

HR: Backwater ratio

H

1

Y

4

Bridge piers (D’Aubuisson’s formula)

Press the Edit button under Geometry and Loss factors.

River Network Editor

The details of the bridge geometry and location are inserted in the appropriate boxes:

77

River Network Editor

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 2.40 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.

78

Figure 2.40

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:

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

MIKE 11

Tabular view: Structures

Geometry and loss factors are viewed by pressing the Edit button under

Geometry and Loss factors.

Figure 2.41

Nagler and Yarnell Bridge piers geometry property page.

River Network Editor

Figure 2.42

Nagler and Yarnell Bridge piers Loss factor property page.

Opening width, b: The total opening width between the piers.

– 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:

79

River Network Editor

80

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 2.43

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.

Figure 2.44

Overflow, FHWA WSPRO, property page.

Bridge level (top): Vertical level of the road.

– Length: Width of top of embankment in the direction of flow.

MIKE 11

Tabular view: Structures

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

.

2.3.5

Regulating

River Network Editor

Figure 2.45

Regulating structure property page.

81

82

River Network Editor

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 2.45) 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. 169).

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

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.

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.

MIKE 11

Tabular view: Structures

2.3.6

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.

Figure 2.46

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.

River Network Editor

83

84

River Network Editor

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.

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. 85).

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.

Use initial value

If an initial value is requested this check box must be checked.

Initial Value

If the ‘Use initial value’ checkbox is checked the initial value must be written in this field.

MIKE 11

Tabular view: Structures

Head loss factors

The factors determining the energy loss occurring for flow through hydraulic structures.

Radial Gate Parameters

The look of the control structure property page when a radial gate is cho-

sen is shown in Figure 2.47.

River Network Editor

Figure 2.47

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.

85

86

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. (1.59) and

(1.61) in the reference manual.

Height

Height above sill of the overflow crest of the gate when the gate is closed,

see Figure 2.48.

Radius

Radius of gate, see Figure 2.48.

Trunnion

Height above sill of centre of gate circle, see Figure 2.48.

Weir Coeff.

Coefficient used when calculating the flow above the gate. Corresponds to

α in eqs. (1.63) and (1.64) in the reference manual.

Weir Exp.

Coefficient used when calculating the flow above the gate. Corresponds to

β in eqs. (1.63) and (1.64) 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. 60) 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. 60) in the reference manual.

MIKE 11

Tabular view: Structures

Figure 2.48

Definition of a radial gate.

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

River Network Editor

87

88

River Network Editor 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 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 2.46 or Figure 2.47 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. 87) 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

Direct Gate Operation: This is the default calculation mode, which determines the value of the gate level directly (gate discharge in case of a discharge gate).

MIKE 11

Tabular view: Structures

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

T s

{

y

ref

y

}

α

3

K

T

T 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 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. 95). 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. 87) 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

Iteration / PID (p. 95).

River Network Editor

89

90

River Network Editor

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.

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.

MIKE 11

Tabular view: Structures

Concentration: A concentration of any compound.

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’.

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. 92) for a list of the internal varia-

bles 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.

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: ‘Control Strategy’, ‘Control- and Target point’, ‘Iteration/PID’ and ‘Logical Operands’.

River Network Editor

91

Control Strategy

River Network Editor

92

Figure 2.49

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. 91). 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:

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.

MIKE 11

Tabular view: Structures

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.

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. 101).

River Network Editor

93

Control and Target Point

River Network Editor

94

Figure 2.50

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. 90).

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.

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

MIKE 11

Tabular view: Structures

‘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. 101).

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. 91).

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

‘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. 101).

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.

Iteration / PID

PID-Section: Here the necessary data is entered if the calculation mode is

chosen as PID-operation.

River Network Editor

95

River Network Editor

96

Figure 2.51

The Iteration / PID property page when calculation mode is chosen as PID-Operation.

Integration Time, Ti: Corresponds to T

i

in eqn. (2.1).

Derivation Time, Td: Corresponds to T

d

in eqn. (2.1).

Proportionality Factor, K: Corresponds to K in eqn. (2.1).

Weighting factor for time step 1, a1: Corresponds to

α

1

eqn.(2.1).

in

Weighting factor for time step 2, a2: Corresponds to

α

2

(2.1).

in eqn.

Weighting factor for time step 3, a3: Corresponds to

α

3

(2.1).

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.

MIKE 11

Tabular view: Structures

River Network Editor

Figure 2.52

The Iteration / PID property page when calculation mode is chosen as Iterative Solution.

Value -: This field corresponds to Limit

Low

in eqn. (2.2).

Value +: This field corresponds to Limit

High

in eqn. (2.2).

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.

97

Logical Operands

River Network Editor

98

Figure 2.53

The Logical Operand property page.

As stated in Control definitions (p. 87) it is possible to define a number of

conditions that all must be evaluated to TRUE if the whole ‘if’-statement 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 2.53. 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.

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.

MIKE 11

Tabular view: Structures

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. 101).

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.

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.

River Network Editor

99

100

River Network Editor

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.

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.

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’.

MIKE 11

Tabular view: Structures

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.

Sum of Discharges

River Network Editor

Figure 2.54

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

in eqn. (2.3).

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.

Branch: The name of the branch with the grid point / structure from

which the discharge should be taken.

101

River Network Editor

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.

2.3.7

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.

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).

102 MIKE 11

Tabular view: Structures

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 2.55.

River Network Editor

Figure 2.55

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

branch, see Figure 2.55.

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

103

River Network Editor 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

104

Figure 2.56

The Dambreak structure property page.

This Dambreak structure property page is used for inserting dambreak

structures in a given network. The property page (see Figure 2.56) 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.

MIKE 11

Tabular view: Structures

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.

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

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. 143).

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.

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.

River Network Editor

105

106

River Network Editor

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.

This specification takes place through the Boundary Editor (p. 169).

2 Erosion Based: MIKE 11 calculates the breach development by use of a sediment transport formula for which the parameters are specified in

the Dambreak Erosion Dialog.

Time Step Control

At the specified time after failure the time step is multiplied with the given factor and 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.

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.

MIKE 11

Tabular view: Structures

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.

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.

2.3.8

Dambreak Erosion

River Network Editor

Figure 2.57

The Erosion property dialog.

This dialog (Figure 2.57) is accessed from the Dambreak Str. (p. 102)

property page in the Tabular view: Structures (p. 50) by pressing the

107

108

River Network Editor

. 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 z

Downstream slope: Slope (horizontal: vertical) of the downstream face of the of the dam structure.

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:

– as a breach starting at the top of the dam

MIKE 11

Tabular view: Structures or

– 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. 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.

River Network Editor

109

2.3.9

User Defined Structure

River Network Editor

110

Figure 2.58

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.

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.

MIKE 11

Tabular view: Structures

2.3.10 Tabulated Structure

River Network Editor

Figure 2.59

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 2.59) whose functionality is described below:

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.

111

112

River Network Editor

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 downstream 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.

MIKE 11

Tabular view: Structures

2.3.11

Energy Loss

Discharge factor: The discharge factor is multiplied to the discharge

in the table.

River Network Editor

Figure 2.60

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 expansions 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)

113

River Network Editor 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.

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

114 MIKE 11

Tabular view: Routing 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. 41).

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

Figure 2.61.

River Network Editor

115

River Network Editor

116

Figure 2.61

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”

is shown in Figure 2.62.

River Network Editor

Figure 2.62

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.

117

River Network Editor

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 2.63.

118

Figure 2.63

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.

MIKE 11

Tabular view: Routing

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’.

2.4.4

Flood control by orifice

The dialog for specifying the parameters for “Flood control by orifice” is

shown in Figure 2.64.

River Network Editor

Figure 2.64

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.

119

River Network Editor

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

Figure 2.65.

120

Figure 2.65

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.

MIKE 11

Tabular view: Routing

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.

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 2.66 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 2.66

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

River Network Editor

121

River Network Editor located upstream of a Kinematic Routing branch are defined in the same way.

Figure 2.67

Definition of Kinematic Routing branches.

122

Details

Figure 2.68

Definition of Kinematic Routing elements.

The dialog used to define a Kinematic Routing branch is shown in

Figure 2.67, while the dialog used to define Kinematic Routing elements is shown in Figure 2.68.

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.

MIKE 11

Tabular view: Runoff / groundwater links

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.

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

123

2.5.1

MIKE SHE links

River Network Editor

124

Figure 2.69

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.

MIKE 11

Tabular view: Runoff / groundwater links

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 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.

River Network Editor

125

126

River Network Editor

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 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.

MIKE 11

Tabular view: Runoff / groundwater links

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.

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

River Network Editor

127

128

River Network Editor 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.

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.

MIKE 11

Tabular view: Runoff / groundwater links

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.

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.

River Network Editor

129

2.5.2

Rainfall-runoff links

River Network Editor

130

Figure 2.70

Rainfall-runoff links dialog.

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.

MIKE 11

Tabular View: Grid Points

2.6

Tabular View: Grid Points

River Network Editor

Figure 2.71

Grid points dialog.

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

131

132

River Network Editor 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: Total number of h-points

Q: h * :

Total number of Q-points

Total number of selected h-points

Filename.nwk

11

Q * :

Branch

Name:

US Chn:

Total number of selected Q-points

Name of the branch

DS Chn:

Length: h:

Q: h * :

Chainage of the upstream end of the branch

Chainage of the downstream end of the branch

Length (m) of the branch

Number of h-points in the branch

Number of Q-points in the branch

Q * :

Number of selected h-points in the branch

Number of selected Q-points in the branch

MIKE 11

Tool bars

Table 2.3

Level in tree view (right hand part)

Branches

Content of the list view (left hand part)

Chainage: Chainage of the grid point. A check mark before the chainage indicates that the grid point is selected.

Type: h or Q.

Data: 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.

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. 44) 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 2.72. In the following the functionality of each of the icons in the

tool bar is explained.

River Network Editor

133

River Network Editor

134

Figure 2.72

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 created 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

MIKE 11

Tool bars

River Network Editor 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.

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

as shown in Figure 2.73.

135

Incorrect branch connection

River Network Editor

Correct branch connection

Figure 2.73

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 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.

Figure 2.74

Tool bar for editing alignment lines.

136 MIKE 11

Tool bars

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 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 2.75

shows an alignment line before and after splining. Five points have been added between all existing points

River Network Editor

137

Before splining

River Network Editor

After splining

138

Figure 2.75

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.

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

MIKE 11

Tool bars 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.

River Network Editor

139

River Network Editor

140 MIKE 11

C R O S S S E C T I O N E D I T O R

141

142 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:

3.1 Raw data View (p. 143)

3.2 Processed data view (p. 155)

3.3 Importing cross sections using File Import (p. 158).

3.4 Exporting cross sections using File Export (p. 163)

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

143

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

Dialog boxes

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

(see Context sensitive pop-up menus).

144 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 3.4).

Datum

A datum may be entered here which is added to all vertical coordinates in the tabular view.

Coordinates

Plane 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

145

146

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 by activating the

‘Calculate angle’ button.

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

θ

Figure 3.2

Definition sketch of the correction angle.

Morphological Model

A level of division can be entered. This level of division is used for acti-

vating the flood plain description as specified in section 6.4 Flood Plain

Resistance (p. 275).

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 and raw data are synchronized i.e. if both views are open the data displayed corresponds to the same cross section.

MIKE 11

Raw data View

Update processed data automatically

Ticking of this box ensures automatic updating of processed data.

Additional buttons

Insert cross section

Pressing this button activates a pop up dialog as shown below.

Cross Section Editor

Figure 3.3

The Insert branch dialog.

In this dialog the appropriate information is entered and OK is pressed.

View processed data

This button activates the processed data view.

Update markers

This button updates markers 1,2 and 3 as the extremes of the cross section.

Note this facility overwrites user settings of these three markers unless the appropriate boxes under Settings –> Cross section.... –> Update Markers have been unticked.

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.

147

Cross Section Editor

3.1.2

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 3.4).

Figure 3.4

Resistance combo box. 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.

148 MIKE 11

Raw data View

Cross Section Editor

Figure 3.5

Select marker dialog box.

A number of markers may be set in this dialog:

– Left/right levee bank: Defines the extend 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.

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.

149

150

Cross Section Editor

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.

Context sensitive pop-up menus

Selecting a river branch or cross section with the right mouse button will open context sensitive pop-up menus. The following editing facilities are available:

Copy Cross Section

The Copy Cross Section dialog is activated from the pop-up menu in the tree display of the raw data view. A cross section chainage must be selected before activating the pop-up menu.

A dialog requests a Topo-ID, branch name and chainage before copying the cross section.

Rename Cross Section

The rename cross section dialog is activated from the pop-up menu in the tree display of the raw data view. A cross section must be selected before activating the pop-up menu. A new cross section chainage must then be entered.

Insert Branch

The Insert Branch dialog is activated from the Insert Cross Section button on the raw data view or by selecting Insert on the tree view pop-up menu.

A dialog requests the River Name, Topo-ID and Chainage of a cross section to be inserted on the selected river branch.

Copy Branch

The copy branch dialog is activated from the pop-up menu in the tree display of the raw data view. The Topo-ID of the river branch must be selected before activating the pop-up menu.

A dialog requests a river branch name and Topo-ID before copying the cross sections.

MIKE 11

Raw data View

Rename Branch

The Rename Branch dialog is activated from the pop-up menu in the tree display of the raw data view. A river branch must be selected before activating the pop-up menu. A new river branch name must then be entered.

Combine Branch

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.

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:

Specifies the method for combining sections. Currently only one option is available:

Cross Section Editor

151

Cross Section Editor

152

Figure 3.6

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.

Insert Interpolated

This feature is only available when selecting a cross section. The cross section editor gives the user the possibility of inserting interpolated cross sections in a given set-up. When selecting this feature a dialog appears.

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 z z

Calculate processed data: The processed data is calculated as the cross sections are created.

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.

MIKE 11

Raw data View

3.1.3

The Cross section 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

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.

Apply to all sections

This option activates a dialog with a number of options. To change any of the below please tick the respective ‘change’ tick box.

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 division can be set here.

Raw data - Resistance Type

The global resistance type 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.

Action to be done

A number of options to be applied to all the cross sections in the set-up are available:

Cross Section Editor

153

Cross Section Editor z z z

Update zone classification.

Update correction angle.

Update markers.

z

Recompute all.

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.

3.1.4

Graphical Settings

Graphics settings

The graphics settings consists of a tree structure view of all possible settings for the graphical elements of the cross section editor. The desired elements are ticked and the properties are set using the right hand side of the dialog box.

Drawing Settings

A number of settings are available:

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 is drawn in black. 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.

154 MIKE 11

Processed data view

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.)

3.1.5

Miscellaneous settings

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

Dialog used for setting the default settings of the resistance column in the tabular view of the cross section editor.

3.1.6

Update Markers settings

This dialog is used for setting the markers which should be automatically updated when activating the update markers button.

3.2

Processed data view

Selecting the View Processed Data button on the Raw data View (p. 143)

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 3.7).

Cross Section Editor

155

Cross Section Editor

Figure 3.7

The processed data view.

3.2.1

Tabular View

The processed data is calculated from the raw data and contains the following parameters:

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

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.

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.

156 MIKE 11

Processed data view

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. 278) Property Page of the Hydrodynamic Editor

(p. 265) is multiplied by the resistance factor.

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.

Processed Data Levels

The levels dialog controls the number and method of processed data levels selection.

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

Cross Section Editor

157

Cross Section Editor 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.

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:

158 MIKE 11

Importing cross sections using File Import

Cross Section Editor

Figure 3.8

File format of ASCII file used for importing data into MIKE11.

In Figure 3.8 TOPO_ID is to be understood as the topological identifica-

tion 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 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.

159

160

Cross Section Editor

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: 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

MIKE 11

Importing cross sections using File Import

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

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

Cross Section Editor

161

Cross Section Editor

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:

162

Figure 3.9

Format used for importing processed data.

MIKE 11

Exporting cross sections using File Export

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 can be divided by 2 or more spaces or 1 or more tabs). One line for each series of coordinates.

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.

Cross Section Editor

163

Cross Section Editor

3.5

Selecting Cross Sections

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

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.

3.6

Plotting Multiple Cross Sections

In addition to printing the actual content of the graphical view of the raw 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.

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.

164 MIKE 11

Plotting Multiple Cross Sections

Print Multiple Cross Sections, Settings...

This will open the dialog with settings for the multiple cross section plot-

ting, see Figure 3.10.

Cross Section Editor

Figure 3.10

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.

Horizontal and vertical scale options

The horizontal and vertical scale options are equivalent. In the following the horizontal scale options are explained.

165

166

Cross Section Editor

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 width and fixed width:All cross sections will be plotted on an axis with the same width (maximum minus minimum). The minimum value of the 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

167

168 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

169

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.

170 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

171

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);

172 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

173

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.

174

Figure 4.4

Definition of wind direction

MIKE 11

Overview of the Boundary 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.

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;

175

Boundary Editor z

Regulating Structure, is specified to describe the discharge at a regulating structure.

For all three types the location must by specified by giving a branch name and a chainage. For the Dam Break and the Regulating structure a structure ID must also be given.

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.

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.

176 MIKE 11

Overview of the Boundary File

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

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:

177

178

Boundary Editor

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)

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.

MIKE 11

Overview of the Boundary File

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.

Boundary Editor

179

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.

180

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.

181

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.

182

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.

183

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.

184

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

185

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.

186

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

187

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.

188

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.

189

Boundary Editor

190

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-

191

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

192 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

193

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.

194 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

195

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.

196

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

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Boundary Editor

198 MIKE 11

R A I N F A L L - R U N O F F E D I T O R

199

200 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

are described in Section 5.11

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Figure 5.1

Input page to the rainfall-runoff simulation in the Simulation Editor

202

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.

MIKE 11

Specifying model Catchments

5.1

Specifying model Catchments

The catchment page is used to prepare the catchments to be included in the

RR setup (see Figure 5.3).

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.

Rainfall-Runoff Editor

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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 FEH: Flood Estimation Handbook. A method for flood estimation in the UK.

6 DRiFt: A semi-distributed rainfall-runoff model simulating the catchment runoff by consideration of spatial variation of soil characteristics and rainfall patterns.

MIKE 11

The NAM Rainfall-runoff model

7 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 catchment 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.

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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:

– 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

Figure 5.5).

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Figure 5.5

NAM - Surface Rootzone.

MIKE 11

The NAM Rainfall-runoff model

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.

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) with the same time constant (CK1=CK2). 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 recharge TG need to be specified and calibrated. However, to cover also a range of special cases, such as ground water storages influenced by river level variations, a number of additional parameters can be modified.

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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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Figure 5.6

NAM - Ground Water.

MIKE 11

The NAM Rainfall-runoff model

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 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.

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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.

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).

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The NAM Rainfall-runoff model

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.

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.

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Rainfall-Runoff Editor

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).

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.

MIKE 11

The NAM Rainfall-runoff model

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.

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.

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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).

214 MIKE 11

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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Rainfall-Runoff Editor

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.

216 MIKE 11

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

Figure 5.12).

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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 the 9 model parameters:

– 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)

– Time constant for routing baseflow (CKBF)

– Root zone threshold value for ground water recharge (Tg)

MIKE 11

The NAM Rainfall-runoff model

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.

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.

A calibration plot of the results is prepared in the RRcalibration directory and can be loaded via the Plot-composer.

Rainfall-Runoff Editor

Figure 5.13

Message box after autocalibration is finished.

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Rainfall-Runoff Editor

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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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.

MIKE 11

UHM

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

.

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.

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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

– 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.

222 MIKE 11

SMAP

SMAP has five calibration parameters (see Figure 5.15):

Rainfall-Runoff Editor

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).

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Rainfall-Runoff Editor

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 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.

MIKE 11

Urban

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 calculation time step. I.e. it is not the average discharge during the storing interval.

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)

Rainfall-Runoff Editor

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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.

MIKE 11

Urban

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)

Rainfall-Runoff Editor

227

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228

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

MIKE 11

Urban

– 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%.

Rainfall-Runoff Editor

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

.

229

Rainfall-Runoff Editor

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.

230 MIKE 11

Flood Estimation Handbook (FEH)

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:

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231

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232 MIKE 11

Flood Estimation Handbook (FEH)

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.

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233

234

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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.

MIKE 11

Flood Estimation Handbook (FEH)

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.

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235

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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

236 MIKE 11

Flood Estimation Handbook (FEH)

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).

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237

Rainfall-Runoff Editor

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

238 MIKE 11

DRiFt

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.or.

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

Figure 5.19).

Rainfall-Runoff Editor

239

Rainfall-Runoff Editor

240

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).

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 .

MIKE 11

DRiFt

Draining Network file

The draining network file is a grid-file containing the 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 can be created automatically by activating the

‘Create’ button after a DEM-file and a AS k value has been defined. Alternatively, a pre-defined network-file can be loaded by use of the ‘...’ button.

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.

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.

Rainfall-Runoff Editor

241

Rainfall-Runoff Editor

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).

242

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

MIKE 11

DRiFt 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.

The rainfall input is defined in the DRiFt ‘Rainfall’ page (see

Figure 5.21).

Rainfall-Runoff Editor

Figure 5.21

DRiFt Rainfall page (Spatial distribution = Uniform)

243

244

Rainfall-Runoff Editor

Precipitation Rate

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.

Based on the selected combination of spatial and temporal distribution of rainfall, different precipitation data definitions are required (see

Table 5.2):

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 [mm/hour]

Constant value for precipitation rate

Time series file (dfs0) of precipitation as rainfall intensity

Time varying grid-file (dfs2) of precipitation as rainfall intensity

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.

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.

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

MIKE 11

DRiFt no rainfall file exists then by activating this check-box, DRiFt will generate a time varying distributed file. In case this 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

Figure 5.22.

Rainfall-Runoff Editor

245

Rainfall-Runoff Editor

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 multiplier

The precipitation time step is the temporal resolution of the new distributed maps [minutes]. 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.

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)

246 MIKE 11

Time Series

Figure 5.23

Time series Page.

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.

Rainfall-Runoff Editor

247

248

Rainfall-Runoff Editor

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.

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

Section 5.11.

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.

MIKE 11

Time Series

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.

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.

Rainfall-Runoff Editor

249

Rainfall-Runoff Editor

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.

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.

250 MIKE 11

Basin View

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

Digitise catchment boundaries and the location of rainfall stations

Calculate catchment areas z

Calculate weights used for mean area rainfall calculation

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.

Rainfall-Runoff Editor

Figure 5.24

Define Basin Area Dialog.

251

Rainfall-Runoff Editor

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).

252

Figure 5.25

Basin Work Area.

Import Basin Definitions

Import of predefined Basin Definitions from a file with the format:

1 n1

X1 Y1

X2 Y2

.... Xn1 Yn1

2 n2

MIKE 11

Basin View

Rainfall-Runoff Editor

X1 Y1

X2 Y2

.... Xn2 Yn2

#

Line 1: Number of catchment boundary sections and pairs of (x,y)coordinates.

Line 2 - Line4 : (x,y) -coordinates for first catchment boundary section.

Line 5: Number of catchment boundary sections and pairs of (x,y)coordinates.

Line 6- 8: (x,y) -coordinates for second catchment boundary section.

LIne 5 to 8 are repeated for the following sections. The # Marks the of all sections

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.

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).

253

254

Rainfall-Runoff Editor

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

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 ( ).

MIKE 11

Basin View

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

(see Figure 5.28).

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

– Station Objects

– Thiessen Objects

The page “Mouse” is used to adjust the digitizing distance and the Mouse sensitivity for digitizing on the screen.

255

Rainfall-Runoff Editor

256

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.

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.

MIKE 11

Basin View

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.

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).

Rainfall-Runoff Editor

257

Rainfall-Runoff Editor

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).

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.

258 MIKE 11

Result Presentation

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

MikeView for comparing simulated and observed flow while displaying e.g. the Root Zone storage variation, the snow storage, the rainfall etc.

Rainfall-Runoff Editor

259

Rainfall-Runoff Editor

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.

260

Figure 5.31

Example of contents of summarised output from a NAM catchment with observed discharge included.

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

MIKE 11

Result Presentation 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).

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.

261

Rainfall-Runoff Editor

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

5.10.5).

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

which were automatically transferred to the Time series Page are

shown on Figure 5.23.

9 Calculation of Mean Precipitation. The Weighted timeseries were calculated based on the weights prepared as described in the previous step.

262 MIKE 11

A Step-by-step procedure for using the RR-Editor

10 Setup of other input time series. Input Time series for Evaporation,

Temperature and Observed Discharge were included on the Time series

Page (Figure 5.23).

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).

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

Rainfall-Runoff Editor

263

Rainfall-Runoff Editor

264 MIKE 11

H Y D R O D Y N A M I C E D I T O R

265

266 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

Quasi Steady (p. 267)

Add. Output (p. 272)

Flood Plain Resistance (p. 275)

Initial (p. 276)

Wind (p. 277)

Bed Resistance (p. 278)

Bed Resistance Toolbox (p. 281)

Wave Approx (p. 283)

Default values (p. 284)

User Def. Marks (p. 286)

Encroachment (p. 288)

Mixing Coefficients (p. 293)

W. L. Incr.- Curve (p. 295)

W. L. Incr.- Sand Bars (p. 297)

Heat Balance (p. 298)

Stratification (p. 300)

6.1

Quasi Steady

Various parameters required for the quasi steady simulation to be carried out are set here.

Hydrodynamic Editor

267

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.

268 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

269

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

270 MIKE 11

Reach Lengths lengths are used in evaluation of the friction loss from one cross section to the next. For unsteady simulations the reach lengths are ignored.

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

) to the next cross section

271

Hydrodynamic Editor

(increasing chainage). L

LOB

Right Overflow Bank

: Length Left Overflow Bank, L

ROB

: Length

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.

272

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.

MIKE 11

Add. Output

Hydrodynamic Editor

Slope

The free water surface slope.

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.

273

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.

274 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

275

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.

276 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.

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

277

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.

278 MIKE 11

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.

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

279

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

(p. 287)).

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. 415).

280 MIKE 11

Bed Resistance Toolbox

6.8

Bed Resistance Toolbox

Hydrodynamic Editor

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) 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

281

282

Hydrodynamic Editor 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 should be based on the toolbox definitions and which zones the bed resistance number should be taken from the 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.

Note that when using a Chezy or Manning description the maximum bed resistance requires the smallest Manning’s M or Chezy’s C. Similar for the minimum bed resistance requiring the highest resistance number.

Further due to the special description in the friction term in the higher order fully dynamic wave description. The bed resistance toolbox is only available for fully dynamic and diffusive wave descriptions.

MIKE 11

Wave Approx

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

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283

Hydrodynamic Editor 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

284

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

1.7 Coefficients, HD default parameters (p. 56) in the Reference Manual).

MIKE 11

Default values

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

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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 1.35.1 Suppression of convective acceleration term (p. 163) 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

286 MIKE 11

User Def. Marks 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.

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Hydrodynamic Editor

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 (p. 292). 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.

288 MIKE 11

Encroachment

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:

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289

Hydrodynamic Editor

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.

290 MIKE 11

Encroachment

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.

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Hydrodynamic Editor

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).

292 MIKE 11

Mixing Coefficients

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

Hydrodynamic Editor

Figure 6.14

The Mixing Coefficients property page.

293

Hydrodynamic Editor

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.

294 MIKE 11

W. L. Incr.- Curve

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.

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295

Hydrodynamic Editor 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-

296 MIKE 11

W. L. Incr.- Sand Bars points to be included in both the upstream and downstream averaging reach.

6.15 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 6.16 with all the different features all of

which are described below.

Figure 6.16

Water level increment due to sand bars.

6.15.1 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.

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Hydrodynamic Editor

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.

6.15.2 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 z

An observed water level increment.

6.15.3 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.

6.16 Heat Balance

The property page used for setting up heat exchange simulations is illus-

trated in Figure 6.17.

298 MIKE 11

Heat Balance

Hydrodynamic Editor

Figure 6.17

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.

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.

299

Hydrodynamic Editor

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

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.

6.17 Stratification

The property page used for setting up stratified flow simulations is illus-

trated in Figure 6.18.

300 MIKE 11

Stratification

Figure 6.18

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:

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.

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302

Hydrodynamic Editor

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.

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.

MIKE 11

Stratification

Dispersion: Factor vertical viscosity

A factor multiplied on the turbulent viscosity to get the vertical diffusion in the transport equation.

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304 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

305

306 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. 308) 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-

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307

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

x

= –

AKC

+

C

2

q

where

C

: concentration

D

: dispersion coefficient

A

: cross-sectional area

(7.1)

308 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

309

7.1

Sediment layers

Advection-Dispersion Editor

310

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

initial conditions in Height (p. 311) a more detailed initial condition can be specified using a width-Height table, see Parameters (p. 311).

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. 312) 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

311

7.2

Non-cohesive ST

Advection-Dispersion Editor

312

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.

MIKE 11

Ice model

Typical range: 0.50 - 0.65.

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

Active ice model

Constant cross section area

Advection-Dispersion Editor

313

Advection-Dispersion Editor z z z z z z z

Latitude

Latent heat

Specific heat of water

Density of water

Heat flux

Ice density

Air temperature z z z z

Wind speed

Cloudiness

Visibility

Cloud density z z z z

Precipitation

Ice thickness

Ice cover

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.

314 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

The mass in river branches given in the unit specified on the ‘Components’ property page. Total and total accumulated values can be selected.

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

The convective transport is given in the unit specified on the ‘Components’ property page, per seconds. Grid and grid accumulated values can

be selected.

Advection-Dispersion Editor

315

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’.

316

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’.

MIKE 11

Components

Fill WQ components

By selecting the Fill WQ components button a number of predefined component sets for the water quality modules can be accessed.

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.

Advection-Dispersion Editor

317

Advection-Dispersion Editor

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.

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. 316). 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.

318 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

319

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.

320 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

Components (p. 316).

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.

Advection-Dispersion Editor

321

322

Advection-Dispersion Editor

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.

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

Components (p. 316).

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

323

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.

324 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

325

326

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

327

328

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

329

330

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 h

2

(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

--------

, (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

331

332

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

333

334 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

335

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.

336 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

337

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

338

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.

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

339

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.

340

Figure 8.7

The Derived Output tab

MIKE 11

W Q ( B O D / D O ) E D I T O R

341

342 MIKE 11

Level for Water Quality Modelling

9 WQ (BOD/DO) EDITOR

9.1

Level for Water Quality Modelling

It is possible to choose among six model levels corresponding to different sets of state variables for the water quality and/or different descriptions of the transformation of the state variables in the river. The higher the model level, the more execution time the water quality module will require.

The whole idea of having a number of model levels with varying complexity is to have a model which would apply to very simple problems (in terms of variables involved), and also to much more complicated situations where nutrient transport and fractionation of the organic matter (dissolved, suspended and deposited) are included. Using such approach the model will be quick to use and would be able to solve small though still important problems. It can also be used in the most complex situations where the next step would be to apply ecological type models such as a eutrophication model.

9.2

Model Level

Model level 1: BOD and DO

A simple oxygen balance model, only including immediate oxygen demand from degradation of BOD and reaeration.

Model level 2: BOD, with bed/sediment exchange and DO

As model level 1, except that here resuspension and sedimentation are included in the calculation of the BOD balance, and a sediment oxygen demand is included in the dissolved oxygen balance.

Model level 3: BOD, DO, and nitrification

As for model level 1 with the addition of the ammonia / nitrate balances, and the oxygen consumption from the nitrification process. No denitrification is assumed.

Model level 4: BOD, with bed/sediment exchange, DO,

Nitrification and Denitrification

Includes all processes from model levels 2 and 3: resuspension and sedimentation are included in the calculation of the BOD balance, and the ammonia / nitrate balances, plus the oxygen consumption from the

WQ (BOD/DO) Editor

343

WQ (BOD/DO) Editor sediment oxygen demand and the nitrification process are included.

Moreover, denitrification is included.

Model level 5: BOD and DO, including delayed oxygen demand

BOD at this model level is split into three different fractions: dissolved in the water phase, suspended in the water phase, and settled at the river bed. Degradation of the settled BOD fraction at the river bed gives rise to the delayed oxygen demand. This level does not include the nitrogen components ammonia and nitrate.

Model level 6: All processes

Dissolved BOD, suspended BOD, BOD at the river bed, oxygen, ammonia and nitrate. BOD is described as for level 5, and nitrogen components are described as for level 4.

Coliforms (see 9.12) and phosphorus (see 9.13 - 9.16) are optional at all

model levels. Wetlands processes can be included at level Nos. 3, 4 and 6

(see 9.22).

Each data entry menu, has been divided into two parts into which values can be typed.

1 Fields with global values

2 Fields with local values

Global values apply everywhere in the river system, where no local values have been specified.

Local values apply to specific locations in the river system. During computation model values will be interpolated between the locally defined values. Outside the locally specified areas the global parameter values will be used.

9.3

Arrhenius

Arrhenius gives the temperature dependency of a process rate by multiplying with the factor

Θ

(

0

)

(9.1)

In the WQ model all temperature dependencies are described in this way, and the reference temperature, T

0

, is 20 °C. If

Θ is set to be 1.07, the process rate doubles when temperature increases by 10 °C. This is generally a

344 MIKE 11

Degradation reasonable approximation for chemical processes. Biological processes, however, can show more variability.

9.4

Degradation

This property page offers the possibility to add and edit degradation related data.

There are three parameters specifying the degradation of BOD. In the first field, a global value for the first order decay rate for dissolved BOD at

20 o C, K

1

, is shown. The physical unit is 1/day.

In the second field a global value of the Arrhenius temperature coefficient for the decay rate is shown, it is dimensionless.

In the last field the half-saturation oxygen concentration in the Michaelis-

Menten expression describing the influence of oxygen in the BOD decay,

K

S

, is shown, in the unit of g O

2

/m 3 . The BOD decay decreases at low O

2 concentrations due to the depression of bacterial BOD degradation under anaerobic conditions.

The decay of BOD is calculated as

Degradation =

K

BOD

1

⋅ Θ

( )

-----------------------

K

2

DO

+

2

DO

2

(9.2) where DO is the concentration of dissolved oxygen.

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.5

Degradation at the bed (levels 5 and 6)

This property page offers possibility to add and edit bed degradation related data.

There are four parameters for degradation of organic matter at the river bed.

In the first field, a global value for the first order decay rate for sediment

BOD at 20°C, K

1

, is shown. The physical unit is 1/day.

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345

WQ (BOD/DO) Editor

In the second field a global value of the Arrhenius temperature coefficient for the decay rate is shown, it is dimensionless.

In the third field the background sediment oxygen demand at 20°C is specified. The unit is g O

2

/m 2 /day. The baseline sediment oxygen demand is the basic demand of oxygen originating from the river bed due to natural sources of organic matter, that is, not as a result of the pollution sources studied by the modelling. The oxygen demand due to settling of BOD from the pollution sources is taken into account by the BOD decay at the river bed, for which the rate constant is specified by the first parameter in this menu.

In the last field the Arrhenius temperature coefficient for the oxygen demand at the river bed is specified.

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.6

Bed/sediment (levels 2 and 4)

This property page offers possibility to add and edit bed / sediment related data in connection with modelling bed / sediment exchange.

There are five coefficients for Bed/Sediment on this model level.

In the first field the background sediment oxygen demand at 20°C is specified. The unit is g O

2

/m 2 /day. The sediment oxygen demand is the basic demand of oxygen originating from the river bed due to natural sources of organic matter, that is, not as a result of the pollution sources studied by the modelling.

In the second field the Arrhenius temperature coefficient for the oxygen demand at the river bed is specified.

In the third field the resuspension of sedimented organic matter is specified as g BOD/m²/day.

In the fourth field the settling velocity is specified for suspended organic matter in m/day.

In the fifth field the critical flow velocity, where net resuspension/deposition is zero, is specified. The critical flow velocity is given in m/sec. When the flow velocity is below this value, sedimentation is assumed, and the parameter specified in the previous field is used. When the flow velocity

346 MIKE 11

Bed / Sediment (Model Levels 5 and 6) exceeds this value, resuspension is assumed, and the parameter specified in the second field is used.

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.7

Bed / Sediment (Model Levels 5 and 6)

This property page offers possibility to add and edit sediment / bed related data in connection with modelling delayed oxygen demand.

There are five coefficients for Bed/Sediment on this model level.

In the first field a 1st order adsorption constant must be specified for the adsorption of dissolved organic matter from the water on the river bed.

The unit is m/day.

In the second field the resuspension of sedimented organic matter is specified as g BOD/m²/day.

In the third field the settling velocity is specified for suspended organic matter in m/day.

In the fourth field the critical flow velocity, where net resuspension/deposition is zero, is specified. The critical flow velocity is given in m/sec.

When the flow velocity is below this value, sedimentation is assumed, and the parameter specified in the previous field is used. When the flow velocity exceeds this value, resuspension is assumed, and the parameter specified in the second field is used.

In the last field the critical concentration of organic matter at the river bed is specified as g BOD/m². In case of concentrations below this value there will be no resuspension of organic matter from the bed irrespective of the flow velocity (this is effectively the same as setting the parameter in field

No. 2 to zero).

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.8

Nitrogen Contents (Model Levels 3 and 4)

This property page offers possibility to add and edit nitrogen contents related data.

WQ (BOD/DO) Editor

347

WQ (BOD/DO) Editor

The title Nitrogen contents covers the nitrogen release from BOD decay and the uptake of ammonia by bacteria and plants. The parameters for these processes are necessary, in order to describe the nitrogen transport and transformation in the river. The menus for the immediate oxygen demand levels (3 and 4) and the level including both immediate and delayed oxygen demand (6) are different due to the differences in the description of the BOD, e.g. modelling three BOD fractions when delayed oxygen demand is included.

Three parameters for nitrogen contents are required in the case of modelling only immediate oxygen demand.

In the first field a value for the release of ammonia-nitrogen is given for the degradation of organic matter, in the unit g NH4-N / g BOD.

In the second field the uptake by the plants of ammonia-nitrogen relative to the net photosynthesis (= photosynthesis - respiration) at the maximum rate of photosynthesis is specified. The unit is g NH4-N uptaken / g O

2 released.

In the last field the uptake of ammonia-nitrogen by bacteria must be specified relative to their uptake of oxygen. The unit is g NH4-N uptaken/ g O

2 used.

In summary:

First field

Global value for the release of ammonia at BOD decay (g NH4-N/g O

2

)

Second field

Global value for the uptake of ammonia in plants proportional to the net photosynthesis (g NH4-N/g O

2

)

Third field

Global value for the ammonia uptake in bacteria proportional to their degradation of BOD (g NH4-N/g O

2

)

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.9

Nitrogen Contents (Model Level 6)

This property page offers possibility to add and edit nitrogen contents related data.

348 MIKE 11

Nitrogen Contents (Model Level 6)

The title Nitrogen contents covers the nitrogen release from BOD decay and the uptake of ammonia by bacterial and plants. The parameters for these processes are necessary, in order to describe the nitrogen transport and transformation in the river. The menus for the immediate oxygen demand levels (3 and 4) and the level including both immediate and delayed oxygen demand (6) are different due to the differences in the description of the BOD, e.g. the fractionation when delayed oxygen demand is included.

Five parameters for nitrogen contents are required in the case of modelling both immediate and delayed oxygen demand.

In the first three fields values for the release of ammonia-nitrogen are given for the degradation of dissolved organic matter, suspended organic matter and sedimented organic matter respectively. All three values have the unit g NH4-N/gBOD.

In the fourth field the uptake by the plants of ammonia-nitrogen relative to the net photosynthesis (= photosynthesis - respiration) at the maximum rate of photosynthesis is specified. The unit is g NH4-N uptaken/g O

2 released.

In the last field the uptake of ammonia-nitrogen by bacteria must be specified relative to their uptake of oxygen. The unit is g NH4-N uptaken/g O

2 used.

In summary:

First field

Global value for the release of ammonia at BOD dissolved decay

(g NH4-N/g O

2

)

Second field

Global value for the release of ammonia at BOD suspended decay

(g NH4-N/g O

2

)

Third field

Global value for the release of ammonia at BOD bed decay

(g NH4-N/g O

2

)

Fourth field

Global value for the uptake of ammonia in plants proportional to the net photosynthesis (g NH4-N/g O

2

)

WQ (BOD/DO) Editor

349

WQ (BOD/DO) Editor

Fifth field

Global value for the ammonia uptake in bacteria proportional to their degradation of BOD (g NH4-N/g O

2

)

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.10 Nitrification

This property page offers possibility to add and edit nitrification related data.

There are four parameters related to nitrification.

Select either n = 1 for an ordinary 1st order reaction, or n = 0.5 for a ½- order reaction (biofilm resisted transport).

In the first field the rate constant for the nitrification at 20°C is stated. If n

= 1 has been selected as reaction order, the rate constant must be specified as 1/day. If n = 0.5 has been selected as reaction order, the unit is

(mg/l)

½

/day.

In the second field the Arrhenius temperature coefficient for the nitrification rate must be specified.

In the last field, oxygen demand by nitrification is given in the unit of g O

2

/g NH4+-N.

The half-saturation constant for oxygen, specified under BOD degradation, is also applied for nitrification.

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.11

Denitrification

This property page offers possibility to add and edit denitrification related data.

The denitrification is a process which takes place under anaerobic conditions in the river, e.g. in biofilm at surfaces of stones, gravel and plant leaves. By this process nitrate is transformed into free nitrogen, which eventually escapes to the atmosphere due to its low water solubility. The

350 MIKE 11

Coliforms denitrification can be an important process for nitrogen removal in the river. In order to have a proper nitrogen balance, this process has to be included whenever it is known to occur.

Three parameters are required to model denitrification.

Select either n = 1 for an ordinary 1st order reaction, or n = 0.5 for a ½order reaction, (biofilm resisted transport).

In the first field the rate constant for the nitrification at 20°C is stated. If n

= 1 has been selected as reaction order, the rate constant must be specified as 1/day. If n = 0.5 has been selected as reaction order, the unit is

(mg/l) ½ /day.

In the second field the Arrhenius temperature coefficient for the denitrification rate must be specified.

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.12 Coliforms

This property page offers possibility to add and edit coliform related data.

The decay of coliforms is dependent on the light intensity in the water column, the temperature and the salinity.

Coli decay =

K C coli

⋅ Θ

(

T

)

⋅ Θ

S

SAL

⋅ Θ

I

I

(9.3)

Global values for the first order decay rates, K, for faecal and total coliforms, respectively, are specified in the first two fields, at 20 ºC, total darkness and zero salinity. The default decay coefficients have been found from experiments with water polluted with coli bacteria where corrections for temperature, salinity and light have been made.

WQ (BOD/DO) Editor

351

WQ (BOD/DO) Editor

The Arrhenius temperature coefficient, T, is specified in the third field.

The salinity coefficient, S, is specified in the fourth field.

The light coefficient, I, is specified in the fifth field.

The light extinction coefficient,

η, is specified in the sixth field. The light intensity, I, is the average light intensity calculated as:

I

=

I

0

(

1 exp

ηZ

( –

ηZ

)

) where I

0

is the surface light intensity, and Z the water depth.

The salinity, SAL, is specified in the last field.

(9.4)

9.13 Phosphorus Content (Model Levels 1 to 4)

This property page offers the ability to add and edit data related to phosphorus modelling.

There are two parameters to be specified on this page, describing the content of phosphorus in organic matter (BOD) originating from pollution sources, and in plants.

In the first field, the phosphorus content in BOD must be specified, as g P

/ g O

2

.

In the second field, uptake of phosphorus by plants per g O

2 production = production – respiration) is specified.

produced (net

352 MIKE 11

Phosphorus Content (Model Levels 5 and 6)

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.14 Phosphorus Content (Model Levels 5 and 6)

This property page offers the ability to add and edit data related to phosphorus modelling.

There are four parameters to be specified on this page, describing the content of phosphorus in organic matter (BOD) originating from pollution sources, and in plants.

In the first three fields, the phosphorus content must be specified, as g P / g O

2

for dissolved, suspended and bottom BOD, respectively.

In the last field, uptake of phosphorus by plants per g O

2 production = production – respiration) is specified.

produced (net

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.15 Phosphorus Processes in the Water Phase

This property page offers the ability to add and edit data related to phosphorus modelling.

There are four parameters to specify on this page, dealing with the degradation and formation of particulate phosphorus suspended in the water phase.

In the first field a first order decay rate is specified, at the reference temperature 20 °C.

In the second field the corresponding Arrhenius temperature coefficient is specified.

In the third a first order rate for the formation of particulate phosphorus from orthophosphate is specified (first order with respect to orthophosphate). This rate is also given at the reference temperature 20 °C.

In the last field the corresponding Arrhenius temperature coefficient is specified.

WQ (BOD/DO) Editor

353

WQ (BOD/DO) Editor

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.16 P. exchange with the bed

This property page offers the ability to add and edit data related to phosphorus modelling.

There are three parameters to specify on this page, dealing with phosphorus exchange between the river bed and the water phase.

In the first field, the resuspension rate is specified.

In the second field, the sinking velocity for particulate phosphorus is specified.

In the last field the critical flow velocity, where resuspension = deposition, is specified. If the flow velocity (calculated by the HD-module) is below the critical velocity, sedimentation is assumed to occur, with the sinking velocity specified in the second field. If the flow velocity exceeds the critical velocity, resuspension is assumed to occur, with the rate specified in the first field.

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.17 Temperature

This property page offers possibility to add and edit temperature related data.

The temperature will be computed as the result of the difference between solar energy input (only during light hours) and the energy loss due to emitted heat radiation (during night and day).

There are four parameters for temperature.

1 In the upper field on the menu the latitude (degrees) of the location of the river is given.

2 In the second field a global value of the maximum heat radiation of the river is specified. The unit is kJ/m²/hour.

354 MIKE 11

Oxygen processes

3 In the third field a global value of the displacement of the maximum temperature of the stream from 12 noon is specified. If the river temperature reaches its maximum after 12 noon, the displacement of time will be positive. Conversely, the displacement of time will be negative if the maximum temperature is reached before 12 noon. The displacement of time is stated in hours.

4 In the last field a global value of the emitted heat radiation from the river is entered using the unit of kJ/m²/day.

The global values will be used by the WQ-module throughout the river system. Global values can be substituted for specific locations.

Note: Temperature is not modelled when the Mike 12 thermocline/halo-

cline hydrodynamic model is used as basis.

The global values will be used by the WQ module throughout the river system. Local values can be given for specific locations.

9.18 Oxygen processes

This property page offers possibility to add and edit oxygen processes related data.

The factors affecting the oxygen concentration are photosynthetic production and respiration, reaeration (exchange with the atmosphere), BOD decay and nitrification. The two latter processes are specified on separate menus. The oxygen menus include the photosynthetic processes and the reaeration.

There are six parameters for oxygen processes.

1 In the upper field the number (1 through 6) of the selected expression for the calculation of the reaeration constant at 20°C is shown. The

Thyssen expression (1) is recommended for application to small streams, O’Connor-Dubbins (2) to ordinary rivers, and the Churchillexpression (3) to rivers with high flow velocities. The equations 4 through 6 can be specified by the user, by pressing the button

WQ (BOD/DO) Editor

See later for a description of how to apply different expressions for reaeration at different locations of the river setup.

355

356

WQ (BOD/DO) Editor

2 In the second field the Arrhenius temperature coefficient for the reaeration constant is specified.

3 In the third field, respiration of plants and animals at 20°C is given.

The unit can be specified to be either g O

2

/m 2 /day or g O

2

/m 3 /day.

4 In the fourth field the Arrhenius temperature coefficient for respiration of plants and animals is entered.

5 In the fifth field, maximum oxygen production by photosynthesis is given, in the same unit as specified for respiration.

6 In the last field the displacement of the time of the maximum oxygen production of the river from 12 noon is stated. If the river has its oxygen maximum after 12 noon, the displacement of time will be positive.

Conversely, the displacement of time will be negative, if the maximum oxygen concentration is reached before 12 noon. The displacement of time is stated in hours.

A first estimate of the oxygen parameters: production, respiration and reaeration constants can be carried out from measured diurnal variations of the oxygen concentrations. This can be done with measurements from only one station, but this approach requires a number of vague assumptions concerning the conditions of the river (uniform topography and uniform oxygen fluctuations for the entire river). Measurements from two stations, however, do not involve assumptions concerning the physical conditions of the river and is therefore recommended. The method is based on a simplified oxygen balance which implies that the river reach must be unaffected by pollution sources, e.g. BOD decay, ammonia oxidation and sediment oxygen demand. The measurement stations thus have to be positioned in a non polluted part of the river. The simple balance reads: dC dt

=

K

2

⋅ (

C m

C

)

R

+ where

C

oxygen concentration (mg/l)

C m

R

oxygen concentration at saturation (mg/l) respiration (g O

2

/m 3 /day or g O

2

/m 2 /day)

P(t) photosynthetic production (g O

2

/m 3 /day or g O

2

/m 2 /day)

K

2 reaeration constant (day -1 )

(9.5)

MIKE 11

Oxygen processes

t

time (day)

The oxygen production at night is nil, which means the respiration and reaeration can be estimated from the night measurements. The reaeration constant is usually not constant hence it varies with the physical conditions of the river and is calculated in the model by an expression including this (either a standard equation or a user defined). Also the production and respiration can very well change along the river. However, the outlined estimation method can be a great help as the first attempt to estimate respiration and production. They will, however, very often have to be tuned during the calibration. The unit for respiration/production can be specified per m 2 (benthic production) or per m 3 (pelagic production)

The reaeration coefficient can be calculated either according to some standard expressions applicable for different types of rivers or streams or from user defined expressions. The major factors affecting the reaeration constant are the current velocity, the river slope, the water depth and the temperature. The temperature is included by an Arrhenius temperature function as mentioned above.

For more information about reaeration, see Reaeration (p. 359).

Defining the local values must follow a number of specific rules. First of all, there is no interpolation between the selected expressions at different chainages. This means that if you want an expression to be valid at a stretch of the river you have to specify the chainage and the requested expression number at the beginning and end of the stretch. An example of this is shown below. The global value is applied everywhere else. The expressions 1 through 4 can be used for river stretches.

Secondly, if you only specify an expression to be used at one point (chainage) then it will only be applied at this specific location. This is actually the way to use the expressions 5 and 6. These can only be applied for one chainage, which as an example could be a weir at which the reaeration process is very different from the river conditions. In the example shown below, the global expression is valid everywhere except for the chainages

1.000 and 2.000 and 5.000 - 6.000, for which expressions Nos. 2 and 4 are used, respectively. Chainages 3.000 and 4.000 are defined as structures. At these two points expressions 5 and 6 will be applied, respectively.

The figure below shows the resulting combination of expressions in a schematic way.

WQ (BOD/DO) Editor

357

WQ (BOD/DO) Editor

Figure 9.1

Combination of reaeration expressions

The third general rule for specification of local expressions is that only one expression can be specified for a chainage. This means that if a point definition is made in a stretch which is already defined by a local expression this stretch must be split. When expression Nos. 5 and 6 are to be used at points of the river where a local expression is applied, then this river stretch has to be split into sections at each side of the point definition. The order of the definitions is arbitrary.

9.19 Degradation in the water phase

This property page offers possibility to add and edit water phase degradation related data.

There are five parameters specifying the degradation of BOD in the water.

In the first and the third field, a global value for the first order decay rate,

K

1

, for dissolved and suspended BOD, respectively, at 20°C is shown. The physical unit is 1/day.

In the second and fourth field, a global value of the Arrhenius temperature coefficient for the decay rate,

Θ, for dissolved and suspended BOD, respectively, is shown. It is dimensionless.

In the last field the half-saturation oxygen concentration in the Michaelis-

Menten expression describing the influence of oxygen in the BOD decay,

K

S

, is shown, in the unit of g O

2

/m 3 . The BOD decay decreases at low O

2 concentrations due to the depression of bacterial BOD degradation under anaerobic conditions.

358 MIKE 11

Reaeration

The decay of BOD is calculated as

Degradation =

K

1

BOD

⋅ Θ ⋅

K

2

DO

2

-----------------------

+ DO

2

(9.6) where DO is the concentration of dissolved oxygen. This equation applies for dissolved, as well as suspended, BOD. Different values for K

1 however, used.

are,

9.20 Reaeration

The reaeration coefficient can be calculated either according to some standard expressions applicable for different types of rivers or streams or from user defined expressions. The major factors affecting the reaeration constant are the current velocity, the river slope, the water depth and the temperature. The temperature is included by an Arrhenius temperature function. In this menu an expression for the reaeration constant K

2

is chosen.

at 20°C

This dialog offers possibility to modify the user’s own expressions for reaeration, and to view parameters applied in the three built-in expressions.

All expressions have the same mathematical formulation, only the parameters differ.

K

2

=

a u b

h c

I d

(9.7)

K

2

u h

reaeration constant at 20°C (g O²/m²/day) flow velocity (m/s) water depth (m)

I

river slope

The user can choose between six options for the expression for the reaera-

tion constant, see below, and in the Oxygen processes (p. 355) property

page.

All six expressions are based on empirical relationships between the reaeration constant and flow velocity, water depth and river slope. The three

WQ (BOD/DO) Editor

359

360

WQ (BOD/DO) Editor first expressions are standard expressions, whereas the fourth, fifth and sixth can be specified by the user.

1 Thyssen expression

K

2

=

0,931

h

– 0,692

I

The Thyssen expression is recommended for calculations in small streams.

2 O'Connor Dubbins expression

(9.8)

K

2

= 3 9

u

h

( )

(9.9)

The O’Connor Dubbins expression is recommended for ordinary rivers.

3 Churchill expression

K

2

=

– 1,67

(9.10)

The Churchill expression is recommended for rivers with high flow velocities.

Custom expressions

4

5

K

2

=

a

3

u b

3

h c

3

I d

3

(9.11)

K

2

=

a

2

u b

2

h c

2

I d

2

6

K

2

=

a

1

u b

1

h c

1

I d

1

(9.12)

(9.13)

MIKE 11

Non point pollution interface

b c d

The user can specify coefficients for three different reaeration expressions. No. 4 can be applied globally, Nos. 5 and 6 can only be applied at point locations. This can be done in structures, where the water is strongly aerated.

If (4-6) Own expressions are chosen, coefficients must be specified for the expressions. The fourth expression can be applied for a river system similar to the three standard equations. These expressions (e.g. 1-4) can be specified locally as well as globally. The expressions five and six are applicable only for a chainage not for a river stretch. They are intended to be used at weirs, falls etc. where the reaeration process has to be described different from the river.

First of all a global expression has to be specified. This is either done by editing the upper field of the global part of the oxygen processes property page, e.g. by typing the number of the expression (1 through 4, remember to define No. 4 if that is chosen) or by selecting the appropriate expression in the present dialog.

The coefficients of the Own expressions can be specified. The own values are:

a

coefficient of the reaeration expression (proportionality factor) exponent for the flow velocity of the water exponent for the water depth exponent for the river slope

9.21 Non point pollution interface

Please read the lower part of the dialog explaining the different parameters used.

9.22 WETLAND

9.22.1 Introduction

The retention and removal of nutrients (N and P) in areas such as riparian wetlands, floodplains, reed swamps and engineered wetlands, have long been considered as an energy-efficient treatment system.

WQ (BOD/DO) Editor

361

WQ (BOD/DO) Editor

The agricultural and industrial utilisation of the natural wet zone between the terrestrial and the aquatic system has reduced these important buffer zones in the last 30-100 years. Nowadays, artificial or constructed wetlands are used as primary or secondary treatment of wastewater in many countries. Non-point sources of nutrients are becoming more and more the bottleneck in controlling the nutrient run-off to rivers and lakes, especially in the Western-like countries. The use of wetlands as nutrient traps is one available method for reducing the nutrients in wastewater or water transported with rivers.

The WETLAND model has been designed with the purpose to have an instrument capable of simulating the significant nutrient removal processes, their interrelationship, and their effects on the river water quality.

9.22.2 Integration with WQ

The WETLAND developed by DHI is an integral part of the Water Quality (WQ) model. This means that river branches with adjacent floodplains, and selected branches that constitute a wetland area, can be modelled explicitly with WETLAND - in parallel with WQ modelling for conventional river branches.

The user can specify branches that shall be modelled with WETLAND

(substituting WQ) and the threshold water level for which the WETLAND processes shall be activated.

This means that is possible within the same simulation to simulate WQ in the open river channel and WETLAND in the adjacent floodplain areas.

The integration works in the following way: In each time step, the branches that are defined as Wetlands will be activated. If the actual water level is below the specified wetland flooding level, there will be no impact on the river water quality from wetland processes. Should the actual water level exceed the wetland flooding level, the WETLAND calculations will influence the river water quality proportional with the water volume that is in contact with the floodplains. The WQ processes will also be calculated and affect the river water quality with the water volume representing the

open channel part in the cross-section, see Figure 9.2

362 MIKE 11

WETLAND

Figure 9.2

WETLAND integration with WQ

9.22.3 The Model

The WETLAND model embraces 4 components in the water phase (NH

4

N, NO

3

-N, PO

4

-P and Particulate-P) and 8 attached to the sediment/peat

-

(plant N/P biomass, labile N/P organic matter, stabile N/P organic matter, immobile N and adsorbed N).

In the WETLAND model, which is a relatively simple model, both aerobic (assumed to occur in a constant oxic microzone) and anaerobic processes (in the saturated zone) are simulated, e.g. nitrification is modelled in the aerobic zone while denitrification takes place in the anaerobic zone.

Uptake and mineralization of nutrients together with immobilisation/adsorption processes and sedimentation/resuspension of particulate matter are also modelled. The modelled processes are illustrated in fig. 8.3

WQ (BOD/DO) Editor

363

WQ (BOD/DO) Editor

364

Figure 9.3

The WETLAND model

The biological/physical system described in the WETLAND model consists of coupled processes where changes in one component could influence other components depending on the biological/chemical reactions.

The model describes 4 components or variables in the water phase, all which are coupled to the transport/spread simulation from the AD module:

AMMONIA

NITRATE

PHOSP. DISS.

PHOSP. PART.

NH

4

-N concentration in surface water

NO

3

-N concentration in surface water

PO

4

-P concentration in surface water

Particulate-P concentration in surface water

These four components are identical with the components for nutrients applied in WQ model level Nos. 3, 4 and 6. This also implies that WET-

LAND only can be activated at model levels Nos. 3, 4 or 6. Phosphorus processes are as in the WQ model optional.

In addition to the four water phase components 8 more components in the sediment/peat are modelled which do not need AD specifications as they not are transported in the water phase (stationary variables). Initial condi-

tions, however, must be specified (see 9.24). The stationary variables are:

MIKE 11

Wetland General

PLANT-N

LABILE ORG-N

STABILE ORG-N

ADSORBED-N

IMMOBILE-N

PLANT-P

LABILE ORG-P

STABILE ORG-P

The plant biomass per area expressed in nitrogen

The concentration of fast degradable (labile) organic matter per volume sediment/peat expressed in nitrogen

The concentration of slow degradable (stabile) organic matter per volume sediment/peat expressed in nitrogen

The concentration of adsorbed ammonia in peat

(per volume sediment/peat)

The concentration of microbial (immobile) nitrogen in peat (per volume sediment/peat)

The plant biomass per area expressed in phosphorous

The concentration of fast degradable (labile) organic matter per volume sediment/peat expressed in phosphorous

The concentration of slow degradable (stabile) organic matter per volume sediment/peat expressed in phosphorous

In the '<file>WQAdd.res11' (additional output) file you will find the simulated value of these eight stationary variables together with miscellaneous aggregated values.

9.23 Wetland General

This page offers the possibility to include wetland processes for selected branches, and to define some general parameters:

Sediment thickness

An empirical parameter for the relative influence of sediment/peat processes (adsorption and immobilisation of NH

4

-N) on the water quality. The sediment/peat processes calculated per volume sediment/peat will be corrected for the specified sediment thickness. The parameter can be interpreted as the mean depth for the horizontal surface water flow through the peat.

Depth when completely flooded

A parameter for the highest point of the wetland area relative to the surface water level. If the value is zero then the surface water always covers the wetland area 100% regardless of the actual water level, whereas a

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365

WQ (BOD/DO) Editor value greater than zero means that the coverage will be less than 100% if the actual water level is greater than the value of the parameter. The actual coverage will be calculated during the simulation. The coverage determines the impact of the biological processes on N and P concentration, e.g. 50% coverage imply 50% impact etc. In the model, hilly wetland areas will thus have a low influence on the water quality compared to a more flat area, if the same amount of water is flowing through the wetland.

Temperature coefficient

The value of 'teta' in the Arrhenius temperature function (see 9.3). The

same function is used for all temperature dependant processes in the model.

Activating WETLAND processes, see Integration with WQ

9.24 Wetland Nitrogen

This page offers the possibility to specify parameters for wetland nitrogen processes, all applied globally:

Maximum nitrification rate

Max. Production rate per m 2 at 20

°C

Half-saturation concentration, nitrification

K m

in the Michaelis-Menten expression

Maximum denitrification rate

Max. Respiration rate per m 2 at 20

°C

Half-saturation concentration, denitrification

K m

in the Michaelis-Menten expression

Mineralisation rate, labile pool

1st order decay of fast degradable (labile) organic matter in sediment/peat at 20

°C

Mineralisation rate, stabile pool

1st order decay of slow degradable (stabile) organic matter in sediment/peat at 20

°C

Immobilisation rate

The immobilisation rate per m 3 (microbial uptake) of NH

4 ment/peat at 20

°C

-N in the sedi-

366 MIKE 11

Wetland Phosphorus

Half-saturation concentration, immobilisation of NH4-N

K m

in the Michaelis-Menten expression

Microbial mortality rate

1 st order mortality (dead rate) of microbial biomass at 20

°C

N-adsorption capacity

Adsorption capacity (mass per volume sediment/peat) of NH

4 sediment/peat. The adsorption is reversible.

-N in the

Half-saturation concentration, adsorption of NH4-N

K m

in the Langmuir adsorption expression

N-Adsorption rate

1 st order rate, N-adsorption at 20

°C

The yearly N Plant production

The aggregated yearly uptake of N in plants, mass per area. The seasonal distribution follows a latitude-dependant sun radiation formula

Ratio of dead plant material to labile

The ratio of fast degradable (labile) organic nitrogen in plant material.

9.25 Wetland Phosphorus

This page offers the possibility to specify parameters for wetland phosphorous processes, all applied globally:

Half-saturation concentration, adsorption of PO4-P

K m

in the Michaelis-Menten expression

P-adsorption rate

The (irreversible) P-adsorption rate per area to the sediment/peat

Mineralisation rate, labile pool

1st order decay of fast degradable (labile) organic matter in sediment/peat at 20

°C

Mineralisation rate, stabile pool

1st order decay of slow degradable (stabile) organic matter in sediment/peat at 20

°C

The yearly P Plant production

The aggregated yearly uptake of P in plants, mass per area. The seasonal distribution follows a latitude-dependant sun radiation formula.

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367

WQ (BOD/DO) Editor

Ratio of dead plant material to labile

The ratio of fast degradable (labile) organic phosphorous in plant material

Sedimentation rate, max

1 st order rate, max. sedimentation, for particulate-P. The maximum rate is applied when the plant biomass reaches its optimum

Sedimentation rate, min

1 st

order rate, min. sedimentation, for particulate-P. The minimum rate is applied when the plant biomass reaches its lowest value

Resuspension rate

Rate of resuspension, Particulate-P (mass per area per time)

Critical flow velocity

Value for the critical flow for resuspension/sedimentation of Particulate-P, i.e. velocity above this value implies that resuspension takes place. For velocities below the critical value, Particulate-P will undergo sedimentation.

9.26 Wetland Components

This page offers the possibility to specify initial conditions (global values only) for the eight stationary variables:

Organic-N in peat, e.g. kg/m

3

The concentration of total-N (labile and stabile) in uppermost part of the sediment/peat, i.e. part of the sediment core which affects the quality of the surface water

Ratio of stable organic N

The initial ratio of slow degradable (stable) organic nitrogen

Organic-P in peat, e.g. kg/m

3

The concentration of total-P (labile and stabile) in uppermost part of the sediment/peat, i.e. part of the sediment core which affects the quality of the surface water

Ratio of stable organic P

The initial ratio of slow degradable (stable) organic phosphorus

Adsorbed-N in peat, e.g. kg/m

3

Initial adsorbed NH

4

-N in the sediment/peat

368 MIKE 11

Wetland Components

Plant-N, e.g. g N/m

2

Initial plant N biomass

Plant-P, e.g. g P/m 2

Initial plant P biomass

Immobile-N in peat, e.g. kg/m

3

Initial immobilised N in the sediment/peat.

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WQ (BOD/DO) Editor

370 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

371

372 MIKE 11

10 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. 375)

Transport model (p. 376)

Calibration factors (p. 382)

Data for graded ST (p. 382)

z z z z

Preset distribution of sediment in nodes (p. 384)

Passive branches (p. 384)

Initial dune dimensions (p. 385)

Non-Scouring Bed Level (p. 386)

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.

10.0.1 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).

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373

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.

10.0.2 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

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) z

Meyer Peter and Muller (Bed load) z

Sato, Kikkawa and Ashida (Bed load) z

Ashida and Michiue Model (Bed load and Suspended load) z

Lane-Kalinske (Suspended load)

All of the transport models can be used for both explicit and morphological mode computations.

374 MIKE 11

Sediment grain diameter

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.

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.

10.1 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 10.1 shows an example where the sediment grain diameter is glo-

bally set to 1 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

375

Sediment Transport Editor

Figure 10.1

Example of implementation of local grain diameter.

10.2 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.

376 MIKE 11

Transport model

Figure 10.2

Example of implementation of transport model parameters.

Figure 10.2 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.

10.2.1 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.

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377

378

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.

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

.

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

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.

MIKE 11

Transport model

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).

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.

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379

Sediment Transport Editor

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.

10.2.2 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 10.7.

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 10.3.

380

Figure 10.3

Additional dialog for defining Smart and Jaeggi model factors.

MIKE 11

Transport model

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.

10.2.3 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, an ACSII file named ‘Bedlevel.txt’ can be placed in the data directory (together with the

ST11-file) with specification of another update method. The first line in the ascii file is not read by MIKE 11. The second line should contain the

Identification Number and the bottom level update method:

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

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

If the file ‘Bedlevel.txt’ does not exist, the default method (no 4) is applied. If the file exists, the user is prompted to confirm whether the settings in the file should be used before the simulation starts.

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381

Sediment Transport Editor

A more detailed description on the calculation of bottom levels is given in the NST Reference Manual.

10.3 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 10.4, 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.

Figure 10.4

Calibration factors dialog

10.4 Data for graded ST

The required input data for the simulation of graded sediment transport and sediment sorting are specified on this property page.

382 MIKE 11

Data for graded ST

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.

Global and local values can be specified.

An example of defining 4 fractions (global defined fractions only) is

shown in Figure 10.5.

Figure 10.5

Example of specifying Graded ST data (4 fractions)

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383

Sediment Transport Editor

10.5 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 m

=

K

Q n m m

K i

Q i n i

downstream branches

upstream branches

Qt j

(10.1)

Where

Qt

n 1

m

+ sediment transport rate in branch m

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.

10.6 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 10.6. Sediment can be transported into a passive branch, but no

sediment can be transported out of the branch.

384 MIKE 11

Initial dune dimensions

Figure 10.6

Passive branches property page.

10.7 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 10.7 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’, between chainage 5.000 km and 10.000 km, where the dune height varies linearly between 0.25 m and 0.40 m.

Sediment Transport Editor

385

Sediment Transport Editor

Figure 10.7

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.

10.8 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.

(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.

386 MIKE 11

Non-Scouring Bed Level

Figure 10.8

Non scouring Bed Level property page

Figure 10.8 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.

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387

Sediment Transport Editor

388 MIKE 11

F L O O D F O R E C A S T I N G E D I T O R

389

390 MIKE 11

Basic definitions

11 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.

11.1

Basic definitions

11.1.1

Simulation Period and Time of Forecast

The Time of Forecast (ToF) is defined in relation to the Hindcast and the

Forecast Period in Figure 11.1.The Hindcast Period defines the simulation

period up to ToF and is specified in the simulation file or calculated by the

system; see Chapter 11.1.2, Simulation Mode. The length of the Forecast

Period is always specified in the Forecast Menu, see section 11.2.1

Figure 11.1

Definition of ToF

11.1.2

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

391

Flood Forecasting Editor

cast period, see Figure 11.2. 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.

392

.

Figure 11.2

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 11.3 the hindcast period starts on

the 4 January 1999 at 12:00 and last up to 7 January 1999 at 12:00.

Figure 11.3

Definition of Hindcast period in historical mode

The forecast period is defined in the Forecast Menu.

MIKE 11

Forecast

11.2

Forecast

The main forecast parameters are specified in the Forecast Menu,

Figure 11.4.

Figure 11.4

Basic Forecast Definitions

11.2.1

Forecast length

The Forecast length is equal to the Forecast Period (Figure 11.4). The

length of the Forecast Period can be specified in hours or in days

11.2.2

Include updating

Tick on the appropriate check box to include the updating routine. Update points and parameters are specified on the Update Specification menu;

see section 11.4.

11.2.3

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

393

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 11.3.4.

11.2.4

Alternative Modes

Multiple forecast with historical data

To execute simulations in Historical Mode tick on the Multiple forecast

check box, see Figure 11.4 or below. Additional information about simu-

lating in Historical Mode can be found in Section 11.1.2.

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 11.5

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

(see Figure 11.6).

394 MIKE 11

Forecast

Figure 11.6

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 11.1.2, 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

11.2.5

Location of forecast stations

Forecast points are specified as shown in Figure 11.7 below

Figure 11.7

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-

Flood Forecasting Editor

395

Flood Forecasting Editor tions menu and are stored in a directory structure as illustrated in

Figure 11.8.

Figure 11.8

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 11.8. 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.

11.3

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.

396 MIKE 11

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 11.3.3.

Figure 11.9 shows the Boundary Estimates menu.

Figure 11.9

Boundary Estimates

11.3.1

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.

Flood Forecasting Editor

397

Flood Forecasting Editor

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.

11.3.2

Editing

All files included in the setup menu will be listed in the ‘Editing’ menu as

seen in Figure 11.9 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.

11.3.3

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 11.1 and their effect illustrated in

Figure 11.10 through Figure 11.14.

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 11.1

Case

The time series covers at least the whole forecast period.

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.

No manipulation is required.

Illustration

Figure 11.10

Figure 11.11

398 MIKE 11

Boundary estimates

Table 11.1

Case Estimation method Illustration

Estimated time series starts at ToF but does not cover the whole forecast period

Time series is extrapolated applying the last found value

Figure 11.12

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

During the first 10 HD time steps the boundary data are interpolated between hindcast data at ToF and estimated data

Figure 11.13

Figure 11.14

Figure 11.10 Extrapolation from value at ToF

Flood Forecasting Editor

399

400

Flood Forecasting Editor

Figure 11.11 Estimated boundary conditions as specified.

Figure 11.12 Extrapolation of Estimated boundary conditions

MIKE 11

Boundary estimates

Figure 11.13 Interpolation of Estimated boundary condition

Figure 11.14 Discontinuity at ToF

11.3.4

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

11.2.5 and Figure 11.15 below.

Flood Forecasting Editor

401

Flood Forecasting Editor

Figure 11.15 Estimated boundary directory structure

11.4

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 11.16 shows the Update Specification menu.

402 MIKE 11

Update specifications

Figure 11.16 Update Specification

11.4.1

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.

Flood Forecasting Editor

403

Flood Forecasting Editor

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.

11.4.2

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

404 MIKE 11

Rating curves

11.4.3

Parameters

Table 11.2

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

11.5

Rating curves

Not implemented.

Flood Forecasting Editor

405

Flood Forecasting Editor

406 MIKE 11

B A T C H S I M U L A T I O N E D I T O R

407

408 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

409

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.

410

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.

MIKE 11

Setting up a Batch Simulation

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 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

411

412

Figure 12.2

Example of Batch Simulation setup.

Batch Simulation Editor

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

413

414 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

Fig A.1.1

Flow Resistance and Vegetation A

415

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.

416

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

417

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.

418 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

419

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.

420 MIKE 11

A D D I T I O N A L T O O L S B

421

422 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. 34) 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

423

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:

424 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

425

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.

426 MIKE 11

I N D E X

427

A

Additional output

. . . . . . . . . . . 277

AD

. . . . . . . . . . . . . . . . . 318

Advanced cohesive sediment transport module

. . . . . . . . . . 312

Advection dispersion

Boundary types

. . . . . . . . . . 328

Advection dispersion module

. . . . 311

Advection-dispersion

Components

. . . . . . . . . . . . 320

Alignment lines

. . . . . . . . . . . . . 46

B

Background layers

. . . . . . . . . . . 36

Batch simulation editor

. . . . . . . 419

Bed resistance

. . . . . . . . . . . . 283

Tripple zone approach

. . . . . . 284

Uniform approach

. . . . . . . . . 283

Vegetation

. . . . . . . . . . . . . 285

Bed resistance toolbox

. . . . . . . 286

Branches

. . . . . . . . . . . . . . . . 43

Bridges

. . . . . . . . . . . . . . . . . 63

Piers (D’Aubuisson’s formula)

. . . 79

Submerged

. . . . . . . . . . . . . 77

C

Cohesive sediment transport

. . . . 330

Cohesive sediment transport module .

311

Computational default values

. . . . 289

Computational grid points

. . . . . . 134

Control Structures

Gate types

. . . . . . . . . . . . . . 86

PID operation

. . . . . . . . . . . . 92

Control structures

. . . . . . . . . . . 85

Control definitions

. . . . . . . . . . 90

Control Strategy

. . . . . . . . . . . 95

Head loss factors

. . . . . . . . . . 87

Iterative solution

. . . . . . . . . . 92

Conveyance

. . . . . . . . . . . . . . 159

Cross section

Interpolated

. . . . . . . . . . . . 154

Markers

. . . . . . . . . . . . . . 150

Processed data

. . . . . . . . . . 157

Radius type

. . . . . . . . . . . . 147

Raw data

. . . . . . . . . . . . . . 145

Section type

. . . . . . . . . . . . 147

Settings

. . . . . . . . . . . . . . . 156

Tabular view

. . . . . . . . . . . . 150

Vegetation height

. . . . . . . . . 152

Width

. . . . . . . . . . . . . . . . 158

Zone classification

. . . . . . . . 151

Cross section editor

. . . . . . . . . 145

Culverts

. . . . . . . . . . . . . . . . . 58

Geometry

. . . . . . . . . . . . . . . 59

Head loss factors

. . . . . . . . . . 59

Valves

. . . . . . . . . . . . . . . . 59

D

Dambreak structure

. . . . . . . . . 105

Breach Failure

. . . . . . . . . . . 112

Erosion

. . . . . . . . . . . . . . . 110

Geometry

. . . . . . . . . . . . . . 108

Piping failure

. . . . . . . . . . . . 112

Decay coefficients

. . . . . . . . . . 327

Dispersion

. . . . . . . . . . . . . . . 322

Diversions

. . . . . . . . . . . . . . . 123

E

Encroachment

. . . . . . . . . . . . . 293

Exporting cross sections

. . . . . . . 165

F

File Import

. . . . . . . . . . . . . . . . 32

File import

Cross sections

. . . . . . . . . . . 160

Flood plain resistance

. . . . . . . . 281

G

Groundwater links

. . . . . . . . . . 126

H

Hotstart

. . . . . . . . . . . . . . . . . . 26

I

Ice model

. . . . . . . . . . . . . . . 317

Ida’s method

. . . . . . . . . . . . . . . 21

Import File

Alignment Points

. . . . . . . . . . 33

Initial conditions

. . . . . . . . . . 26

,

281

428 MIKE 11

Advection dispersion

. . . . . . . 324

Input files

. . . . . . . . . . . . . . . . 21

J

Junctions

. . . . . . . . . . . . . . . . . 51

K

Kinematic Routing Method

. . . . . 124

L

Link channels

. . . . . . . . . . . . . . 44

Longitudinal profile

. . . . . . . . . . . 33

M

MIKE SHE

. . . . . . . . . . . . . . . 127

Mixing coefficients

. . . . . . . . . . 298

Model types

. . . . . . . . . . . . . . . 20

N

Network editor

. . . . . . . . . . . . . . 31

Graphical view

. . . . . . . . . . . . 31

Non-cohesive sediment transport

. 316

P

Point numbering

. . . . . . . . . . . . 36

Pumps

. . . . . . . . . . . . . . . . . . 61

Q

Quasi steady state model

. . . . . . . 21

Quasi steady state solver

. . . . . . 275

R

Radial gates

. . . . . . . . . . . . . . . 88

Rainfall-runoff links

. . . . . . . . . . 133

Regulating structures

. . . . . . . . . . 84

Resize network area

. . . . . . . . . . 35

River curvature

. . . . . . . . . . . . 300

Routing

. . . . . . . . . . . . . . . . . 117

Flood control

. . . . . . .120

,

121

,

122

Runoff links

. . . . . . . . . . . . . . 126

S

Sand bars

. . . . . . . . . . . . . . . 302

Sediment

Single layer cohesive component

. . . . . . . . . . . . . 315

Sediment layers

. . . . . . . . . . . . 314

Setting up a Batch Simulation

. . . . 419

Simulation

editor

. . . . . . . . . . . . . . . . 19

mode

. . . . . . . . . . . . . . . . 21

Splines

. . . . . . . . . . . . . . . . . 140

Start of the simulation

. . . . . . . . 28

Steady state simulations

. . . . . . . 21

Storing frequency

. . . . . . . . . . . 27

T

Tabulated structures

. . . . . . 113

,

114

Calculation mode

. . . . . . . . . 115

The advection-dispersion equation

. 312

Time step

Multiplier

. . . . . . . . . . . . . . 25

Tool bars

. . . . . . . . . . . . . . . . 136

U

Unsteady simulations

. . . . . . . . . 21

Urban Rainfall Runoff Module

. . . . 239

User defined markers

. . . . . . . . . 291

W

Water quality components

. . . . . . 321

Water quality module

. . . . . . . . . 311

Wave approximation

. . . . . . . . . 288

Weirs

. . . . . . . . . . . . . . . . 53

,

61

Formula

. . . . . . . . . . . . . . . 54

Geometry

. . . . . . . . . . . . . . 54

Head loss factors

. . . . . . . . . 54

Honma formula

. . . . . . . . . . . 54

Wind

. . . . . . . . . . . . . . . . . . 282

429

430 MIKE 11

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