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

Jennifer C. Adam, Assistant ProfessorCivil and Environmental EngineeringWashington State University

WSU Modeling TeamCivil and Environmental Engineering / State of Washington Water Research CenterJennifer Adam, Assistant ProfessorMichael Barber, Professor and Director of SWWRCKiran Chinnayakanahalli, Postdoctoral AssociateKirti Rajagopalan, PhD StudentShifa Dinesh, PhD StudentMatt McDonald, MS Student

Biological Systems EngineeringClaudio Stöckle, Professor and ChairRoger Nelson, Research AssociateKeyvan Malek, PhD Student

School of EconomicsMichael Brady, Assistant ProfessorJon Yoder, Associate ProfessorTom Marsh, Professor and Director of IMPACT Center

Center for Sustaining Agriculture and Natural ResourcesChad Kruger, DirectorGeorgine Yorgey, Research Associate

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

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

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)

Linked WSU Study Components

1. Biophysical modeling of historical and future water supply and irrigation demand

2. Municipal Demand Forecast3. Hydropower Review4. Regional survey of Columbia River Basin

water managers5. Economic analyses of domestic and

international factors driving agricultural production

6. Outreach

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

Modeling Framework

Models UsedVIC

HydrologyLiang et al, 1994

CropSystCropping Systems

Stockle and Nelson 1994

VIC-CropSyst Model 1. Weather (D)

2. SoilSoil layer depths

Soil water content

3. Water flux (D)Infiltrated water

4. Crop type

Irrigation water = Crop Water Demand

/irrigation efficiency

Sow dateCrop interception

capacityCrop phenologyCrop uptake (D)Water stress (D)

Current biomass (D)Crop Water demand

(D)Harvest dayCrop Yield

VIC CropSyst

D – communicated daily

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

Overview of Framework

VIC

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

III. Irrigation and municipal diversions compared to water

availability and instream flow requirements;

curtailment in dry years

IV. Iteration of coupled simulation

to account for reduced irrigation in

dry years

ColSim

Biophysical Modeling:VIC-CropSyst, Reservoirs,

Curtailment

• Crop Yield

• Irrigation Water Applied

• Adjusted Crop

Acreage

• Selective Deficit

Irrigation

1. Water Supply2. Irrigation Water

Demand3. Unmet Irrigation

Water Demand4. Effects on Crop

Yield

Economic Modeling:Agricultural Producer

Response

Water Management Scenario

Future Climate Scenario

Inputs Modeling Steps Outputs

Integration with Economics

Economic Scenario

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

1. Columbia Basin-Scale and Columbia Mainstem

2. Example Watershed-Scale: Yakima

Results

Water Supply Entering

Washington• Eastern: increasing• Western: decreasing

Top: 2030 Flow (cfs)Bottom: Historical Flow (cfs)

Water Supply Entering Columbia Mainstem

• Eastern: increasing• Western: decreasing

Top: 2030 Flow (cfs)Bottom: Historical Flow (cfs)

Snake River and Columbia River Supplies

Snake River Columbia River

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

SUPPLY:Annual : +3%Jun – Oct: -10%Nov – May: +27%

DEMAND:Annual: +10%

Regulated Supply and In-Stream Flow Requirements at Key Locations Future

(2030)Historical (1977-2006)

Note: Supply is reported prior to accounting for demands

Watersheds Included in Study

Out-of-Stream Demand by Watershed

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

Acknowledgements Peer reviewers Alan Hamlet, Bob Mahler,

Ari Michelson, Jeff Peterson University of Washington Climate

Impacts Group Dana Pride WA Dep. of Ecology

THANK YOU!

SUPPLEMENTARY SLIDES

Yakima

Yakima Unregulated Supply

Yakima Demand

Yakima Unregulated Supply and Demand: Historical vs Future

Historical

Middle Climate Scenario

Yakima Future Supply and Demand: Unregulated vs Regulated Supply

Unregulated Supply

Regulated Supply

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

Curtailment Uncertainties 1) monthly time step of model

2) 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

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

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

Physical Systemof Damsand Reservoirs

Reservoir Operating Policies

Reservoir StorageRegulated StreamflowFlood ControlEnergy ProductionIrrigation ConsumptionStreamflow Augmentation

0100000200000300000400000500000600000700000800000900000

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

Flow

(cfs

)

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

Small reservoirs included for Yakima and Chelan

Withdrawals being based on VIC-CropSyst results

Curtailment decision is made part of the reservoir model

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#*

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#*

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

Yakima Reservoir Model

Irrigation demand from VIC/CropSystCurtailment rulesProratable 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 1st

• Flood space availability

Instream flow

targetsGauge at Parker

T – TranspirationIP – Interception capacityI – InfiltrationIr – irrigationWd- Water demandQ – RunoffQ01 – Drainage from 0 to 1Q02 – Drainage from 0 to 2Qb – BaseflowW0 – water content in 0W1 – water content in 1W2 - water content in 2Tmin, Tmax – daily minimum and maximum temperatureWs – wind speedRH – Relative humiditySR – Solar radiation

Qb

Q12

T

IP

Redistribute I, W0, W1 and W2 to CropSyst layers

Q

Q01

W0,W1, W2

T0, T1, T2, IP, 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 km2)

Crop 2

Non-Crop

Vegetation

CropSyst is

invoked

CropSyst is

invoked

http://www.hydro.washington.edu/2860/ Slide 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 1/16th 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

Uncertainties 1-Future climate (due to GCMs, greenhouse emission

scenarios anddownscaling approach)

2-Model structure (VIC-CropSyst) 3-Water management and economic scenarios4-Cropping pattern - discrepancy between multiple data

sources5-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)

Walla Walla

Walla Walla Supply

Walla Walla Demand

Walla WallaSupply and Demand

Historical

Hadcm_B1

Example WRIA Results: – Supply in WENATCHEE

Example WRIA Results - Demand in WENATCHEE

Example WRIA Results – Supply and Demand in WENATCHEE