Climate and Management Alternatives in Snake River
Basin
Nathan VanRheenen and Richard N. Palmer
Dept. of Civil and Environmental EngineeringUniversity of Washington
Goals of Research
How can the potential impacts of climate change be best mitigated? Goal 1: Develop a model that provides a
“constrained optimal” management strategy for Snake River Basin users
Goal 2: Incorporate Mid-range forecasts into optimization to guide operations
New starting point for policy-makers Optimization Model of SRB (SIRAS) can serve to
illustrate upper bound of benefits associated with management
SIRAS
Considers Major surface water features System uses
e.g., flood control, irrigation, fish, hydropower Groundwater impacts 8 major irrigation districts
Economic Objective Function
SIRAS - Approach
LP/SLP Decomposition Objective Function
Weekly timestep Maximize
Z = Agriculture profit ($) + Hydropower profit ($) - Flood damages ($) - Environmental Target Penalties
Subject to Inflows, PET Water rights Groundwater availability Farmland availability, crop values and costs,
irrigation efficiency Energy demand and rates Infrastructure limitations (reservoir and powerplant
capacity, etc.) Network flow constraints
SnakeSimOperations Model
VICHydrology Model
Changes in Mean Temperature and
Precipitation or Bias Corrected Output
from GCMs
SIRASOptimization Model
SnakeOpt – Decomposition Approach
Run model from 1950-1992 Rolling 5-year window Step 1
Maximize over 5 years (260 mo.)
Extract conditions at week 52 Redefine constraints Rerun first 52 weeks to
determine first year model optimum
Step 2 Move to 2nd 5-year window Redefine constraints with
Step 1 end conditions Proceed with 2nd window as
per Step 1
Step 1: Optimize over 5 years
Step 2: Extract year 1 ending conditions
Step 3: Redefine conditions as constraints
Step 4: Optimize year 1 only with new constraints
Step 6: Move to next rolling 5-year block and repeat Steps 1-5
Step 5: Initialize year 2 starting storage and gw responses
Year 1 Year 2 Year 3 Year 4 Year 5
Year 2 Year 3 Year 4 Year 5 Year 6
End StorageTotal Power
Irrig AreaGW Response
End Storage
GW Response
SIRAS Approach – LP/SLP Decomp
SIRAS Approach – LP/SLP Decomp
1971-1975
1972-1976
1973-1977
1974-1978
1975-1979
1976-1980
1977-1981
71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96
Mid-term Optimization
Forecasting system offers opportunities for informed and science based decision making
Mid-range forecasts provide improved river forecasts Operating suggestions can be updated as conditions
change over the season Economic objective functions can be modified Operation relationships of Snake relative to
Columbia River can be evaluated