OVERVIEW OF RESERVOIR OPERATIONS AND FLOOD RISK MANAGEMENT 255 255 255 237 237 237 0 0 0 217 217 217 163 163 163 200 200 200 COLUMBIA RIVER BASIN 131 132 122 239 65 53 80 119 27 110 135 120 252 174.59 112 92 56 62 102 130 102 56 48 130 120 111 1 Carolyn Fitzgerald, P.E. Chief, Hydrology & Hydraulics Branch U.S. Army Corps of Engineers, Seattle District CRITFC Future of Our Salmon Technical Workshop 2016 Spokane, WA 16 August 2016 The views, opinions and findings contained in this report are those of the authors(s) and should not be construed as an official Department of the Army position, policy or decision, unless so designated by other official documentation. File Name
Columbia River Basin! Drainage area of 259,000 square miles in seven states and Canada.! Primarily a snowmelt-driven system. Average annual runoff at The Dalles is 134 million acre-feet (MAF)! 31 federal generating projects with installed capacity of 22,458 MW. Corps: 14,651 MW Reclamation: 7,807 MW 2
1948 Columbia River Flood 1948 flood destroyed Vanport, Oregon, a city of 20,000-30,000 people About 50-60 people were killed Vanport, Oregon in 1948 Damaged homes, farms, and levees from Bri>sh Columbia (e.g. Trail) all the way to Astoria, Oregon President directs Corps to include flood control in report due four months later. Trail, B.C. in 1948
Authorized Project Purposes Dams are operated as part of a coordinated multiple-purpose reservoir system Flood Risk Management Navigation Hydropower M&I/Irrigation Recreation Fish & Wildlife
Multi-purpose Reservoir System! Operation of system aims to meet several objectives: Providing adequate floodwater storage space in the reservoirs to decrease the downstream flood risk during the winter and spring runoff. Maintaining a high probability that reservoirs will refill at the end of the spring runoff, to provide water for fish operations, power, and meet recreation needs. Accommodating specific seasonal needs for the passage, spawning, and rearing of a variety of fish species, including providing flows to aid juvenile fish migration downstream. Managing for other uses including navigation, irrigation, and water quality. Preserving and enhancing habitat for resident fish. Optimizing power generation within the requirements necessary to meet the other objectives. 5
Storage Reservoir Operation Seasons for Flood Risk Management! September through December Fixed Reservoir Drawdown Season Operators lower reservoirs to predetermined levels since no one can forecast with certainty how much storage space will be needed for flood-risk management. Monthly water volume forecasts, based on the amount of snowpack in the region s mountains, are typically not available until January.! January through April Variable drawdown season Monthly forecasts of runoff volume guide the operation of reservoirs! April through August Operations to manage spring/early summer flood risk Draft and refill must account for location and shape of runoff 6
Peak runoff: 192 MAF 2011 Peak runoff: 61.0 MAF Canada U.S.
Reservoir Storage! The total space available for flood risk management is 24.5 MAF.! Columbia River Treaty doubled storage available for flood risk management.! Total system storage is approximately one-third of the average annual runoff at The Dalles. 8
Operation of Storage Reservoirs! Many storage reservoirs have space requirements driven by a Storage Reservation Diagram (SRD) 9
Operation of Storage Reservoirs! As water supply forecasts change, storage requirements are updated accordingly. 10
Operation of Storage Reservoirs! As water supply forecasts change, storage requirements are updated accordingly. 11
Operation of Storage Reservoirs! As water supply forecasts change, storage requirements are updated accordingly. 12
Operation of Storage Reservoirs! As water supply forecasts change, storage requirements are updated accordingly. 13
Operation of Storage Reservoirs! As water supply forecasts change, storage requirements are updated accordingly. 14
Operation of Storage Reservoirs! As water supply forecasts change, storage requirements are updated accordingly. 15
Operation of Storage Reservoirs! As water supply forecasts change, storage requirements are updated accordingly. 16
Variability in Runoff Shape! Flood risk management and system design have to accommodate many runoff scenarios.! Operations must account for location and shape of runoff. 17
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Multi-purpose Reservoir System! Typical storage reservoir drafts for flood risk management and refills each year. 19
CRT Flood Risk Assessment Goals! Comprehensive, systems approach! Updating 60 year old economics! Emulating processes developed/ negotiated over 40 years relying on hand regulation! Develop next generation tools and data to analyze project operations
HEC-WAT Watershed Analysis Tool! Coordinated watershed study tool! Integrates hydrology, reservoir, hydraulics, economics, environmental, and statistical software! FRA compute allows a true system-wide benefit analyses assessing risk and uncertainty! Lifecycle, event based Monte Carlo simulations with parameter sampling
HEC-WAT Structure - FRA HEC-WAT with FRA option Forecast Sampler Fragility Sampler Breach Hydrographs Spreading Model Depths, Velocities per Grid Freq Sampler HEC-RAS Model RAS Mapper Depth Grids HEC-FIA Model Mean Forecast HEC- ResSim Regulated Hydrographs Frequency Damages Unregulated Hydrographs Hydrograph Sets Simulation.dss Damage Sets Model Convergence? No
CRT WAT FRA Compute Types! 80 year historic period of record! 19 spring synthetic events & 9 winter synthetic events! 5000 Monte Carlo events: Estimate of 100 yr metrics Designed to compare alternatives, not final metrics! ~50,000 events: Estimate of 500 yr metrics with uncertainty Hydrology and levee knowledge uncertainty sampled
Reservoir Model: HEC-ResSim 24
Flood Risk Assessment: Event Based Modeling Priest Rapids Yakima River Richland West Pasco Pasco L i Kennewick Ice Harbor C n+1 Burbank Plan: BaseCondit:Event1948:RAS-Reach1 River: Columbia Reach: RM 143-Bonn RS: 145.86 50 Legend C n 45 Stage 40 35 Stage (ft) 30 25 20 15 10 Oct Dec Feb Apr Jun Aug Oct 1947 1948 Time
Depth Grid with Structures and Levees
Structures with Damage