A Framework for Formulating Basins Research in Specific Settings: A Case Study of the California Water Plan David R. Purkey, Ph.D. U.S. Water Group Leader Managing Environmental Systems Research Theme Co-Leader Stockholm Environment Institute

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The California Water Plan Legislatively mandated in Updated every 5 years. Prepared by the Dept. of Water Resources. Serves as a programmatic guide to which individual project proposals must make reference. Historically based on traditional gap analysis. With 2003 update, began transition to a scenario-based planning.

WEAP and the California Water Plan Pit R.Pit R. Cow Ck. Battle Ck. Cottonwood Ck Shast a Trinity R. Clear Ck Orovil le South Fk. Feather R. Alma nor Big Chico Ck. Butte Ck. Elder/Thom es Ck East Park/Stony Gorge/Blac k Butte Cache Ck. New Bullards Bar North Fk. Yuba R. Bear R. Folso m Cross Canal North and Middle Fk. American R. North and Middle Fk. Feather R. Upper Pit R. McCl oud R. 1 Net Delta Outflow Stanisl aus R. San Luis San Joaqui n R. Delta- Mendot a Canal Camp Far West Mokelu mne R. Calave ras R. Tuolumne R. Merced R. San Joaquin River Chowchilla/Fr esno R. Made ra Canal Eastside Bypass M ill er to n McCl ure New Don Pedro New Melones New Hogan Pard ee Putah Ck. Yolo Bypass South Fk. American Berryess a Clear Lake Stony Ck. Sacram ento R. Trinit y Sacramento R. Tehama- Colusa Canal Middle and South Fk. Yuba R. Sutte r Bypas s Glen- Colusa Canal Whiske ytown Caman che Cosumn es R. Californi a Aquedu ct Tullo ch Eastman/He nsley DELT A San Luis Friant- Kern Canal San Luis Canal Kings R. Pine FlatsPine Flats Kern R. IsabellaIsabella Tule R. SuccessSuccess Kawea h R. KaweahKaweah James Bypass/Fresno Slough Tulare Lake Coastal Aqueduct

Central Valley WEAP Application

Robust Decision Making Outcome Metrics Uncertainties: Climate and Land Use/Demography Response Package Iterative, analytic process designed to identify strategies that are robust to a wide range of planning uncertainties.

“XLRM” Framework Defines Scope of Analysis Uncertain Factors (X) and ScenariosManagement Strategies (L) and Response Packages Population Land use / Household factors demographic Employment factors scenarios (3) Temperature / Climatic conditions precipitation scenarios (12) Strategy cost factors Agricultural water use efficiency Urban water use efficiency Conjunctive management & groundwater storage Recycled municipal water Model (R)Performance Metrics (M) WEAP PA model for Central Valley Supply Reliability (Urban & Agriculture) Exports to Southern California Environmental flow requirements Costs

Downscaled GCM Data Represent Plausible Range of Future Climatic Conditions 13 climate sequences – six climate models x two global emissions scenarios – Historic climate run forward

Demographic and Land Use Scenarios Drive Changes in Demand Demographic and Land Use Factors

% Monthly IFRs Not Met Urban water supply reliability (%) Agricultural water supply reliability (%) Performance of “Current Approach” Under a Single Scenario Current Approach Single scenario Urban Reliability ~ 80% (through 2050) Agricultural Reliability ~ 47% (through 2050) IFRs not met ~ 6% of months (through 2050) 10

% Monthly IFRs Not Met Urban water supply reliability (%) Agricultural water supply reliability (%) Performance of “Current Approach” Under 36 Scenarios Lower Performance 36 Scenario Results Current Approach 11 Note: Under Robust Decision Making, no attempt is made to assign probabilities to any particular scenario.

Urban water supply reliability (%) Agricultural water supply reliability (%) Analysis Identified and Characterized Poor Outcomes Current Approach % Monthly IFRs Not Met “X” = Poor outcomes (bad for 2 of 3 metrics) 12

Considered Water Management Strategies to Reduce This Vulnerability Urban water use efficiency Agricultural water use efficiency Groundwater recharge Recycled water use 13

Grouped Strategies into Response Packages for Analysis Strategies Baseline (#1) #2#3#4#5#6#7 Urban Water Use Efficiency o (current) Agricultural Water Use Efficiency ooo Groundwater Recharge oo+o++++ Recycled Water Use o Response Packages 14

Implementing Additional Strategies Reduces Vulnerability to Climate Uncertainty Increasing cost / effort Reduced number of vulnerabilities Better performance (decreasing number of scenarios in which performance is unsatisfactory) Baseline (#1) #2 #3 #4 #5 #6 15

Implementing Additional Strategies Reduces Vulnerability to Climate Uncertainty Reduced number of vulnerabilities Baseline (#1) #2 #3 #4 #5 #6 16 Better performance (decreasing number of scenarios in which performance is unsatisfactory) Increasing cost / effort

Vulnerabilities Are Reduced With Response Packages Scope Analysis Evaluate Strategies Over Many Scenarios Characterize Vulnerabilities Summarize Tradeoffs Among Strategies “Robust, Adaptive Strategies” And Key Tradeoffs Augment Strategies Base Case Moderate Increases

A Word on Process Stakeholder Advisory Committee – Water Agencies – Local Government – Environmental Organizations – Trade Associations – Tribes Regional Forums State and Federal Agency Network Statewide Analysis Network Scenario Development Panel

Contributions or Complications? The transition from traditional gap analysis to scenario based planning takes time. Replacing the deterministic cognitive model with one based on decision making under uncertainly is unsettling to some actors. The manner in which the large volume of information generated under scenario based planning is presented is very important. Once the uncertainly cognate takes hold, however, actors generally recognize that it is better representation of the real world.

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