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-LeaderStockholm Environment Institute

Partners

The California Water Plan• Legislatively mandated in 1963.• 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

Sacramento River

Tulare Lake

San Joaquin River

Upper Trinity River

Delta

Pit R.

Cow Ck.Battle Ck.

Cottonwood Ck

Shasta

Trinity R. Clear

Ck

Oroville South Fk.

Feather R.

AlmanorBig Chico

Ck. Butte Ck.

Elder/Thomes CkEast

Park/Stony Gorge/Blac

k Butte

Cache Ck.

New Bullards Bar North Fk.

Yuba R.Bear R.

Folsom

Cross Canal

North and Middle Fk. American R.

North and Middle Fk. Feather R.

Upper Pit R.

McCloud R.

1

Net Delta Outflow

Stanislaus R.

San Luis

San Joaquin R.

Delta-

Mendota

Canal

Camp Far West

Mokelumne R.Calaveras R.

Tuolumne R.

Merced R.

San

Joaquin

River

Chowchilla/Fresno R.

Made

ra Canal

Eastside

Bypass

Millerton

McClure

New Don Pedro

New Melones

New Hogan

Pardee

Putah Ck. Yo

lo

Byp

ass

South Fk. American

Berryessa

Clear Lake

Stony Ck.

Sacr

amen

to R

.

Trinity

Sacramento R.

Teha

ma-

Colu

sa

Cana

l

Middle and South Fk. Yuba R.

Sutt

er B

ypas

sGle

n-Co

lusa

Ca

nal

Whiskeytown

Camanche

Cosumnes R.

Californi

a Aquedu

ct Tulloch

Eastman/Hensley

DELTA

San Luis

Friant-K

ern C

anal

San Luis

Canal

Kings R.

Pine Flats

Kern R.Isabella

Tule R.Success

Kaweah R.

Kaweah

James Bypass/Fresno

Slough

TulareLake

Coastal

Aqueduct

Rivers and TributariesIrrigated Agriculture

M&I/ Environ. Demand

Inter-Basin Transfer

Reservoir

Canals and Diversions

InstreamFlow Requirement

Interactive Groundwater

Rivers and TributariesIrrigated Agriculture

M&I/ Environ. Demand

Inter-Basin Transfer

Reservoir

Canals and Diversions

InstreamFlow Requirement

Interactive Groundwater

Irrigated Agriculture

M&I/ Environ. Demand

Inter-Basin Transfer

Reservoir

Canals and Diversions

InstreamFlow Requirement

Interactive Groundwater

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 AnalysisUncertain Factors (X) and Scenarios Management Strategies (L) and

Response Packages

Population Land use /Household factors demographicEmployment factors scenarios (3)

Temperature / Climatic conditions precipitation scenarios (12)Strategy cost factors

Agricultural water use efficiencyUrban water use efficiencyConjunctive management & groundwater storageRecycled municipal water

Model (R) Performance Metrics (M)

WEAP PA model for Central Valley Supply Reliability (Urban & Agriculture)Exports to Southern CaliforniaEnvironmental flow requirementsCosts

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

10

% MonthlyIFRs Not Met

Urban water supply reliability(%)

Agricultural water supply reliability (%)

Performance of “Current Approach”Under a Single Scenario

CurrentApproach

Singlescenario

Urban Reliability ~ 80%(through 2050)

Agricultural Reliability ~ 47%(through 2050)

IFRs not met~ 6% of months(through 2050)

11

% MonthlyIFRs Not Met

Urban water supply reliability(%)

Agricultural water supply reliability (%)

Performance of “Current Approach”Under 36 Scenarios

LowerPerformance

36 ScenarioResults

CurrentApproach

Note: Under Robust Decision Making, no attempt is made to assign probabilities to any particular scenario.

12

Urban water supply reliability(%)

Agricultural water supply reliability (%)

Analysis Identified andCharacterized Poor Outcomes

CurrentApproach

% MonthlyIFRs Not Met

“X” = Pooroutcomes(bad for 2 of 3metrics)

13

Considered Water Management Strategies to Reduce This Vulnerability

• Urban water use efficiency• Agricultural water use efficiency• Groundwater recharge• Recycled water use

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

o o o + + + +++Groundwater Recharge o o + o + +++ +++Recycled Water Use o + ++ + ++ +++ +++

Response Packages

14

15

Implementing Additional Strategies Reduces Vulnerability to Climate Uncertainty

Increasing cost / effort

Reduced numberof vulnerabilities

Better performance(decreasingnumber of scenarios inwhichperformance isunsatisfactory)

Baseline (#1)

#2

#3

#4

#5

#6

16

Implementing Additional Strategies Reduces Vulnerability to Climate Uncertainty

Reduced numberof vulnerabilities

Baseline (#1)

#2

#3

#4

#5

#6

Better performance(decreasingnumber of scenarios inwhichperformance isunsatisfactory)

Increasing cost / effort

Vulnerabilities Are Reduced WithResponse Packages

Scope Analysis

Evaluate Strategies Over Many Scenarios

Characterize Vulnerabilities

Summarize TradeoffsAmong Strategies

“Robust, Adaptive Strategies”And Key Tradeoffs

Augment Strategies

Base Case

ModerateIncreases

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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