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

1. Columbia River Basin Water Supply and Irrigation 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 / State of Washington Water Research Center Jennifer Adam, Assistant Professor Michael Barber, Professor and Director of SWWRC Kiran Chinnayakanahalli, Postdoctoral Associate Kirti Rajagopalan, PhD Student Shifa Dinesh, PhD Student Matt McDonald, MS 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. Predicted Climate Changes • Temperature • Annual temperature increase (0.2 to 1.0°F / decade) • Summer increases are greater than other seasons • Precipitation • Annual precipitation: less agreement among Global Climate Models (small on average: +1 to +2%) • Summer precipitation decreases; other seasons increase • Net Result: shifting of water availability away from summer season of peak irrigation water demand

5. 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)

6. Linked WSU Study Components • Biophysical modeling of historical and future water supply and irrigation demand • Municipal Demand Forecast • Hydropower Review • Regional survey of Columbia River Basin water managers • Economic analyses of domestic and international factors driving agricultural production • Outreach

7. Modeling Framework Unique Aspects of Approach: *Integration of Surface Hydrology and Cropping Systems *Incorporation of Water Management (Reservoirs and Curtailment of Interruptible Irrigation Rights) *Integration with Economic Modeling

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

9. 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

10. 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

11. Overview of Framework I. Coupled simulation of hydrologic cycle and crop growth: all irrigation requirements met II. Runoff, baseflow, and return flow routed through flow network; reservoir simulation accounts for irrigation diversions VIC ColSim IV. Iteration of coupled simulation to account for reduced irrigation in dry years III. Irrigation and municipal diversions compared to water availability and instream flow requirements; curtailment in dry years

12. 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 Water Management Scenario • Adjusted Crop Acreage • Selective Deficit Irrigation • Crop Yield • Irrigation Water Applied Economic Scenario Economic Modeling: Agricultural Producer Response

13. Model Scenarios: Low, Middle, High • Climate Change (Biophysical) Scenarios • Precipitation changes • Temperature changes • Water Management Scenarios • Additional Storage Capacity • Cost Recovery for Newly Developed Water Supplies • Economic Scenarios • Trade • Economic Growth • Supply is also shown for wet, dry, and average conditions

14. Results Columbia Basin-Scale and Columbia Mainstem Example Watershed-Scale: Yakima

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

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

17. Snake River and Columbia River Supplies Snake River Columbia River

18. Regulated Supply vs Demand for Columbia River Basin (at Bonneville) 2030 results are for - HADCM_B1 climate scenario - average economic growth and trade SUPPLY: Annual : +3% Jun – Oct: -10% Nov – May: +27% DEMAND: Annual: +10% Note: Supply is reported prior to accounting for demands

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

20. Watersheds Included in Study

21. Out-of-Stream Demand by Watershed

22. 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 (see our poster on the Yakima River Basin) • 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. • Thinking towards the 2016 Forecast

23. Acknowledgements • Peer reviewers Alan Hamlet, Bob Mahler, Ari Michelson, Jeff Peterson • University of Washington Climate Impacts Group • Dana Pride • WA Dep. of Ecology

24. Thank yoU!

25. Supplementary Slides

26. Yakima

27. Yakima Unregulated Supply

28. Yakima Demand

29. Yakima Unregulated Supply and Demand: Historical vs Future Historical Middle Climate Scenario

30. Yakima Future Supply and Demand: Unregulated vs Regulated Supply Unregulated Supply Regulated Supply

31. Yakima Curtailment and Unmet Demand • Historical (1977-2005) • At least some curtailment of proratable irrigation rights 45% of years (higher than observed) • Unmet Demand: 7,200 – 278,600 ac-ft per year; average of 108,000 ac-ft per year • Future (2030s) • At least some curtailment of proratable irrigation rights for 90% of years • Unmet Demand: 14,300 – 434,000 ac-ft per year; average of 154,000 ac-ft per year

32. Curtailment Uncertainties • 1) monthly time step of model2) we are using a very simplified model and need something like the riverware model to capture all details3) USBR uses a "forecast" of supply which may be different from VIC supply4) demand does not match seasonally with entitlement expectations of USBR in managing the reservoir

33. 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

34. 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) • USBR Diversions: 2.7 MAF/yr (with conveyance losses) • VIC-CropSyst: 2.5 MAF/yr (no conveyance losses) • Results in a reasonable ~20% conveyance loss

35. 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

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

37. 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

38. 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

39. 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

40. 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)

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

42. 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

43. 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)

45. Walla Walla

46. Walla Walla Supply

47. Walla Walla Demand

48. Walla WallaSupply and Demand Historical Hadcm_B1

49. Example WRIA Results: – Supply in WENATCHEE

50. Example WRIA Results - Demand in WENATCHEE