Columbia River Basin Water Supply and Demand Forecast for 2030 Presented by: Keyvan Malek, Washington State University Contributors: J.C. Adam, K. Chinnayakanahalli, K. Rajagopalan, R. Nelson, M.E. Barber, C. Stockle, M. Brady, G. Yorgey, S. Dinesh, C. Kruger Washington State University Presented at: 2 nd annual PNW Climate Science Conference, Seattle Sep, 2011

WSU Modeling Team Dr. Jennifer Adam Assistant Professor, Civil and Environmental Engineering Dr. Claudio Stöckle Professor and Chair, Biological Systems Engineering Dr. Michael Brady Assistant Professor, School of Economic Sciences Dr. Michael Barber Professor and Director, Washington Water Research Center Dr. Kiran Chinnayakanahalli Post-Doctoral Associate, Washington Water Research Center Chad Kruger Director of Center for Sustaining Agriculture & Natural Resources (CSANR) Roger Nelson Research Associate and Programmer, Biological Systems Engineering Kirti Rajagopalan PhD Student, Civil and Environmental Engineering Shifa Dinesh PhD Student, Civil and Environmental Engineering Georgine Yorgey Associate in Research, Center for Sustaining Agriculture & Natural Resources (CSANR)

Outline of Talk  Goals  Background  Modeling Approach  Results  Conclusions

Goals  To project 2030s water supply and demand in the Columbia River Basin  Agricultural and Municipal demands considered  To study the effect of climate change on agriculture (crop water demand, crop yield, cropping pattern)

Background  Columbia River  Water resources sensitive to climate change  Economic value of agriculture (5 billion $ in WA)  Irrigation largest out-of- stream water user  Diverse crop mix

Modeling Approach

Models Used VIC Hydrology Liang et al, 1994 CropSyst Cropping Systems Stockle and Nelson 1994

Overview of Framework

VIC-CropSyst Model 1. Weather (D) 2. Soil Soil layer depths Soil water content 3. Water flux (D) Infiltrated water 4. Crop type Irrigation water = Crop Water Demand /irrigation efficiency Sow date Crop interception capacity Crop phenology Crop uptake (D) Water stress (D) Current biomass (D) Crop Water demand (D) Harvest day Crop Yield VICCropSyst D – communicated daily

T – Transpiration I P – Interception capacity I – Infiltration Ir – irrigation Wd- Water demand Q – Runoff Q 01 – Drainage from 0 to 1 Q 02 – Drainage from 0 to 2 Q b – Baseflow W 0 – water content in 0 W 1 – water content in 1 W 2 - water content in 2 Tmin, Tmax – daily minimum and maximum temperature Ws – wind speed RH – Relative humidity SR – Solar radiation QbQb Q 12 T IPIP Redistribute I, W 0, W 1 and W 2 to CropSyst layers Q Q 01 W 0,W 1, W 2 T 0, T 1, T 2, I P, Wd I CropSyst VIC Ir Daily Tmin, Tmax, Ws, RH, SR, I VIC-CropSyst Coupling Approach

Invoking CropSyst within VIC gridcell Crop 1 VIC grid cell (resolution=1/16°) (~ 33 km 2 ) Crop 2 Non-Crop Vegetation CropSyst is invoked

Crops Modeled  Winter Wheat  Spring Wheat  Alfalfa  Barley  Potato  Corn  Corn, Sweet  Pasture  Apple  Cherry  Lentil  Mint  Hops  Grape, Juice  Grape, Wine  Pea, Green  Pea, Dry  Sugarbeet  Canola  Onions  Asparagus  Carrots  Squash  Garlic  Spinach Generic Vegetables  Grape, Juice  Grass hay  Bluegrass  Hay  Rye grass  Oats  Bean, green  Rye  Barley  Bean, dry  Bean, green Other Pastures Lentil/Wheat type  Caneberry  Blueberry  Cranberry  Pear  Peaches Berries Other Tree fruits Major Crops

Physical System of Dams and Reservoirs Reservoir Operating Policies Reservoir Storage Regulated Streamflow Flood Control Energy Production Irrigation Consumption Streamflow Augmentation VIC Streamflow Time Series The Reservoir Model (ColSim) (Hamlet et al., 1999) Slide courtesy of Alan Hamlet

ColSim Reservoir Model (Hamlet et al., 1999) for Columbia Mainstem Model used as is, except for  Withdrawals being based on VIC-CropSyst results  Curtailment decision is made part of the reservoir model Green triangles show the dam locations

Curtailment Rules (Washington State) Curtailment based on instream flow targets  Columbia Mainstem  Lower Snake  Central Region (Methow, Okanogan, Wenatchee)  Eastern Region (Walla Walla, Little Spokane, Colville) Prorated based on a calculation of Total Water Supply Available  Yakima

Biophysical Modeling: VIC-CropSyst, Reservoirs, Curtailment Crop Yield (as impacted by climate and water availability) Adjusted Crop Acreage Selective Deficit Irrigation 1.Water Supply 2.Irrigation Water Demand 3.Unmet Irrigation Water Demand 4.Effects on Crop Yield Economic Modeling: Agricultural Producer Response Water Management Scenario Future Climate Scenario Inputs Modeling StepsOutputs Integration with Economics Economic Scenario

Model Scenarios: Low, Middle, High  Climate Change Scenarios  HADCM_B1, CCSM_B1, CGCM_B1, PCM_A1B, IPSL_A1B  Hybrid Delta Downscaling Approach (2030s climate)  GCMs and Emission Scenarios chosen for low/middle/high precipitation and temperature change combinations  Water Management Scenarios  Additional Storage Capacity  Cost Recovery for Newly Developed Water Supply  Economic Scenarios  International Trade  Economic Growth

courtesy of Alan Hamlet The UW CIG Supply Forecast

Application of the UW CIG Water Supply Forecast  WSU is building directly off of the UW water supply forecasting effort (Elsner et al. 2010) by starting with these tools that were developed by UW Climate Impacts Group:  Implementation of the VIC hydrology model over the Pacific Northwest at 1/16 th degree resolution  Reservoir Model, ColSim  Historical climate data at 1/16 th degree resolution  Downscaled future climate data at 1/16 th degree resolution  By explicitly incorporating irrigation water demand into this framework, we can explore the coupled dynamics between water supply and water demand

Results -Supply Forecast -Irrigation Demand Forecast

Supply in 2030s for the Columbia River Basin (at Bonneville- the outlet of Columbia river basin)  Annual flows are projected to increase by 3%  Summer flows are projected to decrease by 16% Note: The above numbers are based on an average of all 5 future climate scenarios considered

Water Supply Entering Washington Eastern: increasing Western: decreasing Top: 2030 Flow (cfs) Bottom: Historical Flow (cfs)

Snake River and Columbia River Supplies (Entering Wasington) Snake riverColumbia river

Irrigation and Municipal Demands by Watershed in Washington State

Yakima Supply and Demand Historical Future: Hadcm_B1

Walla Walla Supply and Demand Historical Future: Hadcm_B1

 Projected demand for 2030s (middle climate change and economic scenarios): Columbia River Basin Scale Average annual “top of the crop” irrigation demand increases from 10.7 MAF to 11.8 MAF (increase of 10%) Washington State Average annual “top of the crop” irrigation demand increases from 4.9 MAF to 5.5 MAF (increase of 12%) Impacts on Irrigation Demand

Dam-Regulated Supply versus Demand for Columbia River Basin (at Bonneville) 2030 results are for - HADCM_B1 climate scenario - average economic growth and trade Note: Supply is reported prior to accounting for demands

Conclusions  Supply: we see a small increase (3%) in annual supply in the 2030s  But, summer supplies (when there is irrigation demand) decreases about 16%  Demand: we see a significant increase in annual irrigation demand (10% for the entire Columbia River Basin) in the 2030s  Increased irrigation demand, coupled with decreased seasonal supply poses difficult water resources management questions, especially in the context of competing in stream and out of stream users of water supply.

Acknowledgements  Many thanks to members of the University of Washington Climate Impacts and Land Surface Hydrology Groups  Alan Hamlet  Marketa Elsner  Pablo Carrasco  Se-Yeun Lee  Dennis Lettenmaier  Funding was provided by the Washington State Department of Ecology

THANK YOU!

Uncertainties 1-Future climate (due to GCMs, greenhouse emission scenarios and downscaling approach) 2-Model structure (VIC-CropSyst) 3-Water management and economic scenarios 4-Cropping pattern - discrepancy between multiple data sources 5-Irrigation supply – poor data on groundwater and surface water proportions of the supply 6-Irrigation methods a)No information for upstream states b)Conveyance loss is not explicitly modeled (This is a proportion of the demand at each WRIA)

Change in Crop Yield Crop type Percent change (tons/hectare) Corn Spring Wheat 7.7 Winter Wheat 25.1 Alfalfa 10.0 Apples 0.0 Cherry Orchard 0.0 Potatoes -9.1 Grapes Change in some crop yield - Trees does not show significant change - Results are for full irrigation

Crop Mix Information for the Columbia River Basin  United States Department of Agriculture (USDA)  Washington State Department of Agriculture (WSDA)

Yakima Reservoir Model Irrigation demand from VIC/CropSyst Curtailment rules Proratable water rights prorated according to Total Water Supply Available (TWSA) calculated each month Monthly Inflows from VIC-CropSyst Total System of Reservoirs (capacity 1MAF approx.) Objectives : Reservoir refill by June 1 st Flood space availability Instream flow targets Gauge at Parker