Ice Processes Modeling

Ice Processes Modeling
Ice Processes
Modeling
Technical Team
Meeting –
Riverine Modeling
November 13 - 15, 2013
Prepared by: HDR, Inc.
Prepared for: Alaska Energy
Authority
11/13/2013
DRAFT – SUBJECT TO REVISION
Ice Processes Modeling and Analysis
• Key Ice Questions:
– How does ice cover formation, growth, jamming
affect main channel and lateral habitats?
– Will operational scenarios significantly change
the ice impacts on main channel and lateral
habitats?
• Freeze-up processes
• Mid-winter conditions
• Breakup jamming
11/13/2013
DRAFT – SUBJECT TO REVISION
River Ice Basics
• Generally divide the winter (Oct- May) into 3
periods
– Freeze-up: frazil production, border ice growth,
bridging, ice cover and freeze-up jam formation
• Characterized by cold air temps, relatively steady
discharge (falling), cover progression upstream
– Mid-winter: thermal ice growth, continued frazil
production in open areas
• discharge generally recedes throughout winter
11/13/2013
DRAFT – SUBJECT TO REVISION
River Ice Basics (cont)
– Breakup: ice melting, open areas growing
• Characterized by warming air temps, increasing
discharge, increased solar incidence, snowmelt
runoff, cover thermal and mechanical disintegration
• Breakup ice jams and ice runs can result in highly
unsteady discharge and stage
• Greatest likelihood of overbank flows
• Jamming is a function of snowpack, rate of warming,
date, freeze-up conditions, etc.
11/13/2013
DRAFT – SUBJECT TO REVISION
Freeze-up
Cold air temperatures
Frazil generation
Border ice growth
Steady discharge (falling)
Increase in stage with
passage of ice front
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DRAFT – SUBJECT TO REVISION
Frazil transport stages
11/13/2013
DRAFT – SUBJECT TO REVISION
Breakup
Highly variable discharge
Thermal degradation
Increasing flows
Surges in stage
Overbank flooding
Ice runs
Shear walls
11/13/2013
DRAFT – SUBJECT TO REVISION
Stage and Discharge Dynamics
• Moving vs stopped ice
– Moving (floating) ice travels at nearly the velocity of
the underlying water (low resistance)
– Stopped ice becomes a shear surface nearly
doubling resistance to flow
• Jams vs covers
– Covers are relatively thinner and smoother than
jams (often single layer)
11/13/2013
DRAFT – SUBJECT TO REVISION
Stage and Discharge Dynamics
• Roughness and resistance
– Interaction can lead to cover and jam
consolidation and thickening
– Side channel typically freezes before main
channel, increasing resistance and discharge in
side channel
– May increase discharge in main channel, leading
to thicker cover/jam (higher water levels)
11/13/2013
DRAFT – SUBJECT TO REVISION
Stage during Freeze-up
• Freeze-up at FA-104 (Whiskers Slough)
– Whiskers Slough time lapse
– ESS40 time lapse
• Freeze-up at FA-128 (Slough 8a)
– Slough 8a time lapse
11/13/2013
DRAFT – SUBJECT TO REVISION
FA-104 (Whiskers Slough)
PRM 104.9 Freeze-up 2012
11/13/2013
DRAFT – SUBJECT TO REVISION
FA-104 (Whiskers Slough)
PRM 104.9 Freeze-up 2012
11/13/2013
DRAFT – SUBJECT TO REVISION
ESS40, PRM 106.8
Freeze-up 2012
11/13/2013
DRAFT – SUBJECT TO REVISION
ESS40, PRM 106.8
Freeze-up 2012
11/13/2013
DRAFT – SUBJECT TO REVISION
ESS40, PRM 106.8
Freeze-up 2012
14
12
10
8
6
4
2
0
11/7/2012
11/13/2013
11/12/2012
11/17/2012
11/22/2012
11/27/2012
DRAFT – SUBJECT TO REVISION
12/2/2012
12/7/2012
FA-128 (Slough 8A)
PRM 127.9 Freeze-up 2012
11/13/2013
DRAFT – SUBJECT TO REVISION
FA-128 (Slough 8A)
PRM 127.9 Freeze-up 2012
11/13/2013
DRAFT – SUBJECT TO REVISION
Stage during Breakup
• Initial breakup followed by several ice
runs/re-jamming events
• Breakup at FA-128 (Slough 8a)
– Slough 8a timelapse
– Impacts showing shear walls
– Evidence of very high stages, ice runs
11/13/2013
DRAFT – SUBJECT TO REVISION
FA-128 (Slough 8A)
PRM 127.9 Breakup 2013
11/13/2013
DRAFT – SUBJECT TO REVISION
FA-128 (Slough 8A)
PRM 127.9 Breakup 2013
11/13/2013
DRAFT – SUBJECT TO REVISION
General Modeling Approach
River1D
Dynamic ice modeling
Temperature modeling
Ice generation/growth
Discharge
Stage/under-ice depth
Velocity
Ice thickness
River2D
Static ice cover (specified)
Temperature modeling
Discharge
Stage/under-ice depth
Velocity (2D)
Ice Processes Modeling Team
Study Lead: Jon Zufelt
Lead Modeler: Steve Ertman
U of Alberta: Faye Hicks, Julia Blackburn
11/13/2013
DRAFT – SUBJECT TO REVISION
Model dependencies flow chart
Reservoir
HEC-RAS Flow Routing
River1D Ice
River2D Ice
* (Yrs 25 & 50)
1D Sediment * 2D Sediment
* 2D Hydraulic *
Groundwater
*
HSC/HSI
Open Water
Ice Cover
Both
11/13/2013
Fish Habitat
Operating Scenarios:
- Base Load
- Intermediate Load Following
- Maximum Load Following
- Run of the River
DRAFT – SUBJECT TO REVISION
Water Quality
Effective
Salmon Spawning
Habitat
River1D Hydraulic Overview
• One-dimensional hydraulic flood-routing model
• Detailed compound channels
– Main channel
– Right and left overbanks
• Channel resistance (calibration parameter)
– Manning’s n
– Roughness height
• Simulates steady or unsteady flows
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D Hydraulics-- Continued
• Boundary Conditions
– Upstream Inflow discharge hydrograph
– Lateral inflow discharge hydrographs
– Downstream stage hydrograph or normal depth
• Initial Conditions
– Base flow
– Initial water-surface elevation
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D Ice-Processes Modeling
• Conservation of thermal energy
– Heat exchange between water and atmosphere
– Heat exchange between ice and atmosphere
– Heat exchange between ice and water
• Frazil ice forms when water drops below 0 C
– Frazil slush collects below ice cover
– Frazil ice rises as floes and aggregates as new cover
• Pore water also freezes to form new ice cover
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D Ice-Processes -- Continued
• Heat transferred to ice cover or frazil slush from
atmosphere or water results in melting
• Ice front progresses upstream from ice bridges
– Juxtaposition of ice floes traveling downstream
– Bridge locations must be specified ***
• Channel cross sections occluded by ice and
additional hydraulic resistance of ice cover can
result in dramatic changes to river stage.
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D Ice-Processes Modeling
• Additional data requirements:
– Air temperature
– Inflow water temperature at upstream boundary
– Inflow ice conditions at upstream boundary
•
•
•
•
Suspended frazil concentration
Surface ice concentration
Frazil floe thickness
Solid ice thickness
– Locations and timing of ice bridges
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D Ice-Processes Modeling
• Calibration data requirements:
– Water temperature
– Ice front position with time
– Solid and frazil ice concentrations
– Ice thickness
• Output of River Ice-Processes Model
– Water temperature
– River stage
– Ice profile (both position and thickness)
11/13/2013
DRAFT – SUBJECT TO REVISION
Ice-Processes Modeling
• Capabilities Enhancements for River1D Model
‒ Effort led by Dr. Faye Hicks, River Ice Research
Group, University of Alberta (UA)
‒ HEC-RAS to River1D geometry file converter
‒ Ability to model compound channels (i.e., main
channel and left/right overbanks)
‒ Ability to model natural cross-section geometry
‒ Ability to work directly with Imperial or SI units
‒ Updating User Manual to reflect new capabilities.
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D Model Middle River
• Surveyed geometry at 88 cross sections
• Main channel only. Awaiting overbank geometry to be
developed by others (e.g., LiDAR).
• Interpolated cross sections at 0.2-mile spacing.
• Main-channel Manning’s n from R2’s HEC-RAS
open-water model. Need overbank roughness.
• Upstream inflow hydrograph from USGS 15291700
(Susitna River above Tsusena Creek).
• Calibration interval: August 11-17, 2012
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D Model Middle River – cont’d
• Validating lateral inflows
• Steady-flow test run conducted with successful
convergence.
• Unsteady, open-water calibration (calibration interval:
August 11-17, 2012) matched open-water flow routing
results.
• Additional in-channel open water calibration runs to be
conducted.
• Collect and compile winter data to support ice-processes
modeling.
• Input data needs for River2D open water modeling
identified
11/13/2013
DRAFT – SUBJECT TO REVISION
11/13/2013
DRAFT – SUBJECT TO REVISION
River1D
• Animations of output
11/13/2013
DRAFT – SUBJECT TO REVISION
River2D Ice-Cover Model Overview
• Two-dimensional depth-averaged model
• Spatially variable, triangular, finite-element grid
– Fine spatial resolution
– Detailed bathymetry
• Channel resistance
– Manning’s n
– Roughness height
• Simulates steady or unsteady flows
• Wetting and drying (floodplain inundation)
11/13/2013
DRAFT – SUBJECT TO REVISION
11/13/2013
DRAFT – SUBJECT TO REVISION
River2D Overview -- Continued
• Ice cover is specified ***
– Spatially variable ice thickness
– Thickness does not vary with time
• Evolution of an ice cover can be approximated by
separate model runs at different stages of ice
development.
– Fixed in space horizontally
– Cover is in isostatic balance with water column
• Computation elements seeks isostatic balance
independently
– Ice roughness contributes to channel resistance
11/13/2013
DRAFT – SUBJECT TO REVISION
11/13/2013
DRAFT – SUBJECT TO REVISION
River2D Overview -- Continued
• Boundary Conditions
– Inflow hydrograph
– Outflow Stage or Stage-Discharge Rating Curve
• Model Output
– Channel discharge
– 2D water-surface elevation
– Vertically averaged current velocity
11/13/2013
DRAFT – SUBJECT TO REVISION
11/13/2013
DRAFT – SUBJECT TO REVISION
Ice Processes – Next Steps
•
•
•
Continued River1D modeling (open and ice)
Begin River2D modeling
2013 Freeze-up observation program begun
•
•
•
Previous efforts and data required for River1D
model guide program planning and efficiency
Time Lapse Camera maintenance October
12 freeze-up flights beginning Nov 6, 2013
11/13/2013
DRAFT – SUBJECT TO REVISION
41
Freeze-up Forecasting
Freeze-up progression from 1980s and 2012
Freeze-up 2012
1600.0
1400.0
1200.0
AFDD (C)
1000.0
800.0
600.0
(ESS20)
(ESS40)
(ESS50)
(ESS70)
(ESS80)
22-Oct
23-Oct
25-Oct
26-Oct
29-Oct
1-Nov
7-Nov
8-Nov
15-Nov
18-Nov
20-Nov
28-Nov
250
200
150
PRM
•
100
400.0
50
200.0
0.0
0
9/28/2012 10/8/2012 10/18/201210/28/2012 11/7/2012 11/17/201211/27/2012 12/7/2012 12/17/201212/27/2012 1/6/2013
Date
11/13/2013
DRAFT – SUBJECT TO REVISION
Freeze-up 1982
1600
180
(PATK)
(Denali)
1400
1200
1000
160
(Watana)
(Devils
Canyon)
2-Nov
140
120
12-Oct
800
100
PRM
AFDD (C)
19-Oct
26-Oct
80
600
60
400
40
200
0
28-Sep
11/13/2013
20
0
12-Oct
26-Oct
9-Nov
23-Nov Date 7-Dec
21-Dec
DRAFT – SUBJECT TO REVISION
4-Jan
18-Jan
Number of Days to Freeze
vs.
Freezing Start Date
80
Days to Freeze-up (>196 AFDDs)
70
60
50
40
30
20
10
0
23-Sep
3-Oct
13-Oct
23-Oct
2-Nov
12-Nov
22-Nov
2-Dec
Start of Freezing Season
Number of days for cover to progress to PRM 100 based on Talkeetna
temperatures. Start of Freezing this year is Nov 6, 2013.
11/13/2013
DRAFT – SUBJECT TO REVISION
12-Dec
22-Dec
4000
Discharge at Gold Creek when Freeze-up reaches PRM 100
3500
Discharge (cfs)
3000
2500
2000
1500
1000
Discharge at Gold Creek at Freeze-up
500
Maximum
Minimum
0
2-Nov
12-Nov
22-Nov
2-Dec
12-Dec
22-Dec
Date of Freeze-up at PRM 100
Discharge at Gold Creek when the ice cover reached PRM 100
11/13/2013
DRAFT – SUBJECT TO REVISION
1-Jan
11-Jan
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