Columbia River Basin Water Supply and Demand Forecast for the 2030s

1. Columbia River Basin Water Supply and Demand Forecast for the 2030s Jennifer C. Adam, Assistant Professor Civil and Environmental Engineering Washington State University

2. WSU Modeling Team Civil and Environmental Engineering Jennifer Adam, Assistant Professor Michael Barber, Professor and Director of Washington Water Center Kiran Chinnayakanahalli, Postdoctoral Associate Kirti Rajagopalan, PhD Student Shifa Dinesh, PhD Student Biological Systems Engineering Claudio Stöckle, Professor and Chair Roger Nelson, Research Associate Keyvan Malek, PhD Student School of Economics Michael Brady, Assistant Professor Jon Yoder, Associate Professor Tom Marsh, Professor and Director of IMPACT Center Center for Sustaining Agriculture and Natural Resources Chad Kruger, Director Georgine Yorgey, Research Associate

3. Background • The economic, ecologic, and cultural well being of Washington's Columbia River Basin depends on water • Irrigation largest water user • Economic value of agriculture (5 billion $ in WA) • Water resources sensitive to climate change • Better understanding of future range in supply and demand needed to guide investment decisions

4. Goals • To project 2030s water supply and (agricultural and municipal) demand in the Columbia River Basin • WA Dep. of Ecology Report to State Legislature (November, 2011)

5. Linked WSU Study Components 1. Regional survey of Columbia River Basin water managers 2. Biophysical modeling of historical and future supply and irrigationdemand 3. Economic analyses of domestic and international factors driving agricultural production 4. Municipal demand forecast 5. Hydropower review

6. Modeling Approach Modeling Integration: *Surface Hydrology *Cropping Systems *Water Management *Economics

7. The UW CIG Supply Forecast http://www.hydro.washington.edu/2860/ Slide courtesy of Alan Hamlet

8. 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 1/16th degree resolution • Reservoir Model, ColSim • Historical climate data at 1/16th degree resolution • Downscaled future climate data at 1/16th degree resolution • WSU added elements for handling agriculture: • integrated crop systems and hydrology • irrigation withdrawals from reservoirs, and including some smaller reservoirs, curtailment modeling • economic modeling of farmer response

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

10. Overview of Framework

11. VIC-CropSyst Model VIC CropSyst 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 D – communicated daily

12. VIC-CropSyst : Coupling Approach T T – Transpiration IP – Interception capacity I – Infiltration Ir – irrigation Wd- Water demand Q – Runoff Q01 – Drainage from 0 to 1 Q02 – Drainage from 0 to 2 Qb– Baseflow W0 – water content in 0 W1 – water content in 1 W2 - water content in 2 Tmin, Tmax – daily minimum and maximum temperature Ws – wind speed RH – Relative humidity SR – Solar radiation IP Ir I Q T0, T1, T2, IP, Wd Q01 Daily Tmin, Tmax, Ws, RH, SR, I Q12 Redistribute I, W0, W1 and W2 to CropSyst layers W0,W1, W2 Qb CropSyst VIC

13. Invoking CropSyst within VIC gridcell CropSyst is invoked Crop 2 CropSyst is invoked Crop 1 Non-Crop Vegetation VIC grid cell (resolution=1/16°) (~ 33 km2)

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

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

16. 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

17. 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

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

19. Model Calibration/Evaluation • Calibration: • Streamflows (we used calibration from Elsner et al. 2010 and Maurer et al. 2002) • Crop Yields (using USDA NASS values) • Irrigation Rules (using reported irrigated extent by watershed) • Evaluation: • Streamflows (Elsner et al. 2010 and Maurer et al. 2002) • USBR Diversions from Bank’s Lake (for Columbia Basin Project)

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

21. Model Scenarios: Low, Middle, High • Climate Change Scenarios • HADCM_B1, CCSM_B1, CGCM_B1, PCM_A1B, IPSL_A1B • Hybrid Delta Downscaling Approach (2030s climate) (UW CIG) • 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

22. Draft Results Columbia Basin-Scale and Columbia Mainstem Example Watershed-Scale Yakima Walla Walla

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

24. Water Supply Entering Columbia Mainstem • Eastern: increasing • Western: decreasing Top: 2030 Flow (cfs) Bottom: Historical Flow (cfs)

25. Snake River and Columbia River Supplies Snake River Columbia River

26. Regulated Supply vs 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

27. Regulated Supply and In-Stream Flow Requirements at Key Locations Historical (1977-2006) Future (2030) Note: Supply is reported prior to accounting for demands

28. Watersheds Included in Study

29. Out-of-Stream Demand by Watershed

30. Yakima

31. Yakima Supply

32. Yakima Demand

33. Yakima Supply and Demand Historical Hadcm_B1

34. Walla Walla

35. Walla Walla Supply

36. Walla Walla Demand

37. Walla WallaSupply and Demand Historical Hadcm_B1

38. Conclusions and Future Directions • Changes in supply (average of all climate scenarios) • 3% increase in annual flow at Bonneville • However, 16% decrease in summer flow at Bonneville • Changes in demand (middle econ and climate scenarios) • 10% increase in agricultural demand over basin • 12% increase in agricultural demand over state • Some watersheds more impacted than others • 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.

40. Time Line on Report to State Legislature • Outreach workshops in Spokane, Wenatchee, and Tri-Cities (last month) • Draft Legislative Report has been released: • http://www.ecy.wa.gov/programs/wr/cwp/wsu_supply-demand.html • Final Legislature Report by end of October: • Responses to comments from workshops • High/low economic scenarios • Unmet demand due to curtailment • Full Technical Report by end of year: • Impacts of climate change and curtailment on crop yield • Full economic scenarios

41. Longer-Term Directions • 2016 Report to State Legislature, improvements that are being considered • Groundwater dynamics • Columbia-basin scale economics (not just state-level) • Fuller inclusion of climate change scenarios • More ground-truthing

42. BioEarth • Overarching Goal: To improve the understanding of regional and decadal-scale C:N:H2O interactions in context of global change to better inform decision makers involved in natural and agricultural resource management. http://www.cereo.wsu.edu/bioearth/

43. Acknowledgements • Alan Hamlet and others at UW CIG • Peer reviewers Bob Mahler, Ari Michelson, Jeff Peterson • Dana Pride • WA Dep. of Ecology

44. Thank yoU!

45. Uncertainties 1-Future climate (due to GCMs, greenhouse emission scenarios anddownscaling 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 waterproportions of the supply 6-Irrigation methods a)No information for upstream states b)Conveyance loss is not modeled (This is a proportion of the demand at each WRIA)

46. Change in Crop Yield • Change in some crop yield • Trees does not show significant change • Results are for full irrigation

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

49. Example WRIA Results: – Supply in WENATCHEE

50. Example WRIA Results - Demand in WENATCHEE