Post on 21-Jul-2020
Model Development to Support Assessment of Flood Risk for the Columbia River Treaty Review
U . S . A r m y C o r p s o f E n g i n e e r s
2012 AWRA Washington State Conference Sara Marxen, P.E.
U.S. Army Corps of Engineers Seattle District
September, 2012
Slide 2
U . S . A r m y C o r p s o f E n g i n e e r s
Presentation Outline I. Modeling Goals and Approach II. Data Collected III. Data Developed IV. Models built V. Use in the Treaty Studies
Slide 3
U . S . A r m y C o r p s o f E n g i n e e r s
The Columbia River System
Originates in Canada, Canada has 15% of the basin area, 30% of average annual flow is from Canada, 50% of worst Columbia flood flows (1894) came from Canada.
Flows 1,200 miles through 4 U.S. States, drainage area of 259,000 square miles
Over 60 large dams and reservoirs owned and operated by many different entities
Mica
Keenleyside
Duncan
Libby
Slide 4
U . S . A r m y C o r p s o f E n g i n e e r s
Flood Risk Management Task: Evaluate
Flood Risk Under Current
and Future Operating Scenarios
Goal: Provide Information to
Support a Decision on Future of the
Treaty
EM 1105-2-101: Requires Risk Analysis • Expected Annual Damage • Annual Exceedance Probability • Long Term Risk • Conditional Non-Exceedance • Residual Risk
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U . S . A r m y C o r p s o f E n g i n e e r s
Modeling Goals Implement Flood Risk Management
Models should be flexible, maintainable, adaptable
Accurate geospatial economic data
Integrate hydrologic/reservoir/river/economic
Increase automation in the approach
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U . S . A r m y C o r p s o f E n g i n e e r s
What are we modeling?
There are 1,000 of dams in the basin
Really only 8 of them have specific operations that are regularly used and manageable
Historically there are 22 reservoirs that are modeled as part of “System” Flood Risk Management
More than 60 dams are modeled for hydropower
Slide 7
U . S . A r m y C o r p s o f E n g i n e e r s
Data Collected 1. LIDAR – 1600 river miles, 3000 square miles 2. Use of existing and collection of new river cross-
sections/bathymetry 3. 3-D levee centerlines 4. structure inventory
Slide 8
U . S . A r m y C o r p s o f E n g i n e e r s
Data Developed 1. Hydrology
• 2000 level modified flows dataset
• “Synthetic” Low Probability Events
• Climate Change
2. Standardized run-off volume forecasts
3. Levee fragility
Slide 9
U . S . A r m y C o r p s o f E n g i n e e r s
Models Developed 1. HEC-Ras
2. HEC-ResSim
3. HEC-FIA
4. HEC-WAT with FRA
Slide 10
U . S . A r m y C o r p s o f E n g i n e e r s
Hydraulic Modeling
US
US
US
US
US
US
US
Libby
Hungry Horse
Dworshak
McNary
The Dalles
Grand Coulee Albeni Falls
Slide 11
U . S . A r m y C o r p s o f E n g i n e e r s
CRT System HEC-ResSim
Model
67 projects in the
model
36 with storage that can affect flood operations
8 which operate for “the system”
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U . S . A r m y C o r p s o f E n g i n e e r s
CRT System HEC-ResSim Model
Simulates reservoir operations at a planning level on a daily time-step. Reservoirs were initially chosen for inclusion based primarily on
volume, and whether they were included hydropower or flood studies.
Does not model ecosystem function (biop) operations Simulates the majority of CRT Flood and Hydropower operations Includes - flow routing, automated refill, continuous or refill based
mode
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U . S . A r m y C o r p s o f E n g i n e e r s
CRT System HEC-ResSim Model
Approach to developing post-2024 operations. What will effective use and called upon look like? How can they be designed to provide the same level of flood risk
but meet the treaty description? What does that mean for other users of the system?
Slide 14
U . S . A r m y C o r p s o f E n g i n e e r s
HEC-WAT Structure
HEC-FIA Model
Simulation.dss
WAT Simulation
With Default Program
Order
HMS Model HEC-RAS
Model
HEC-WAT
WAT Simulation
With Default Program
Order
2000 Modified Flows/
Synthetic Events
HEC-ResSim Model
Flow
Hydrologic Data
HEC-ResSim Plug-In
HEC-RAS Plug-In
HEC-FIA Plug-In
Hydrographs
Hydrographs Hydrographs
Damages
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U . S . A r m y C o r p s o f E n g i n e e r s
Flood Risk System In
flow
Qi
Time
Inflo
w Q
i
Time
Inflo
w Q
i
Time
Qi Qb
Qo
Out
flow
Qo
Time
Reservoir 1
Reservoir 2
.
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U . S . A r m y C o r p s o f E n g i n e e r s
HEC-FIA Model
HEC-RAS Model
Regulated Hydrographs
Breach Hydrographs
Damages
HEC-WAT with FRA option
Model Convergence
?
Freq Sampler
Spreading Model
Spreading Model
Frequency
Hydrograph Sets
Damage Sets
No
Fragility Sampler
Simulation.dss
Depths, Velocities per Grid
CSRA
Benefits
Net Benefit
Sampler
Expected Net Benefit,
CDF
Yes
HEC- ResSim
RAS Mapper
Forecast Sampler
Unregulated Hydrographs
Mean Forecast
Depth Grids
HEC-WAT Structure - FRA
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U . S . A r m y C o r p s o f E n g i n e e r s
Flood Risk System In
flow
Qi
Time
Inflo
w Q
i
Time
Inflo
w Q
i
Time
Li Sta
ge (
ft)
Probability of Levee Failure
Qi Qb
Qo
Out
flow
Qo
Time
Reservoir 1
Reservoir 2
.
Res
ervo
ir
Elev
atio
n
Time
Fore
cast
V
olum
e
Observed Volume
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U . S . A r m y C o r p s o f E n g i n e e r s
What does this mean for the Flood Risk Analysis
Year x has a peak of 435,000 cfs at The Dalles with no Called Upon
Rather than this…..
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U . S . A r m y C o r p s o f E n g i n e e r s
What does this mean for Flood Risk Analysis
Forecast Volume
Peak
Flo
w
Example: Each color represents a single year and the effect of forecast uncertainty on the resulting peak flow
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U . S . A r m y C o r p s o f E n g i n e e r s
Uncertainties Incorporated in FRA (short-term)
Forecast uncertainty
Starting reservoir pool elevation
Stage/flow rating curves
Roughness coefficients
Levee breaching parameters/fragility
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U . S . A r m y C o r p s o f E n g i n e e r s
HEC-ResSim Starting Storage/Elevation Stream routing coefficients Stage/flow Rating Curves Reservoir physical data:
storage/elevation, release capacity, etc. Demands (water, power)
Current Power Capacity (outages) Sedimentation changes HEC-RAS
Roughness Coefficients Weir Coefficients Bridge Debris Gate Coefficients Ice thickness Bridge/culvert coefficients Dam/levee breeching parameters Contraction/Expansion coefficients
Boundary Conditions (normal depth slope, etc.)
Terrain Data
HEC-FIA Foundation Height Ground Elevation Structure value Content Value Car Value Other Value Depth/Damage functions Population at Risk
Uncertainties Incorporated in FRA (long-term)
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U . S . A r m y C o r p s o f E n g i n e e r s
Many Other Uncertainties What will be an agreed upon called upon operation? What will be an agreed upon effective use operation? What could a CanadianTreaty Terminates operation look like? What Treaty operation will be agreed upon vs. what we assume? What biological operations will be desirable in U.S. and Canada? How will the basin change over time (people, places, demands)? How will the climate change over time? How will an operation change in real-time implementation, is it
significant?……….
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U . S . A r m y C o r p s o f E n g i n e e r s
Example of using FRA to address this
Arrow Elevation: 70 Yr Avg.
1426.0
1428.0
1430.0
1432.0
1434.0
1436.0
1438.0
1440.0
1442.0
1444.0
1-Oct OCT NOV DEC JAN FEB MAR APR I APR II MAY JUNE JULY AUG I AUG II SEP
Elev
atio
n (ft
.)
Case 1 Case 2: 165 Case 2: 225 Case 3Case 4 Case 4b Case 7 Case 10Case 14 Case 8 Case 9 Case 3bCase 15 Case 4c Case 4q Case 4FB
Arrow Elevations: 70 Yr. Avg.
1395.0
1400.0
1405.0
1410.0
1415.0
1420.0
1425.0
1430.0
1435.0
1440.0
1445.010
/1/2
010
10/1
5/20
10
10/ 2
9/20
10
11/1
2/20
10
11/2
6/20
10
12/1
0/20
10
12/2
4/20
10
1/7/
2011
1/21
/201
1
2/4/
2011
2/18
/201
1
3/4/
2011
3/18
/201
1
4/1/
2011
4/15
/201
1
4/29
/201
1
5/13
/201
1
5/27
/201
1
6/10
/201
1
6/24
/201
1
7/8/
2011
7/22
/201
1
8/5/
2011
8/19
/201
1
9/2/
2011
9/16
/201
1
9/30
/201
1
Out
flow
(kcf
s)
Case 1 (BCH) Case 4C (Recom.)
Case 4FB (Alt. Arrow) Avg 1995-2011 (17 yrs)
Apply probability to the operations cases based on expert knowledge. Incorporate that into flood risk. Case 1 – 50% chance of occurring Case 4FB – 25% chance of occurring Case 4C – 20% chance of occurring Case NCS – 5% chance of occurring
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U . S . A r m y C o r p s o f E n g i n e e r s
What does this mean for the Treaty Studies
We now have a tool in which operational changes in Canada or the U.S. can, relatively quickly, be evaluated for flood risk.
This is only one piece of the puzzle that will be use to make a decision. Multiple studies through STT/SRT are ongoing: – How should called upon and effective use work operationally? – What is the impact of a less conservative flood risk operation? – What is the impact of trying to meet more normative flow levels in the
mainstem? – What is the impact of more normative reservoir levels? – Can levees be improved o reduce flood risk? – Can levees be removed to reduce flood risk? – What is an appropriate system-based dry year operation?
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U . S . A r m y C o r p s o f E n g i n e e r s
Questions
Acknowledgement goes to multiple engineers in Seattle, Portland, Walla Walla, Division Columbia Basin Water Management, Hydrologic Engineering Center, BPA and West Consultants Pete Dickerson, Ryan Cahill, Ron Malmgren, Geoffrey Walters, Kristian Mickelson,Tracy Schwarz, Jeremy Giovando, Travis Ball, Margaret McGill, Joan Klipsch, Matt Fleming, Chris Nygaard, and more!