The document summarizes the use of integrated scenario analysis in California's Water Plan Update 2009. Three scenarios were developed to capture uncertainties around factors like population growth, climate change, and land use to the year 2050. Water demands were projected for each scenario using 12 climate sequences to represent variability. Finer scale analysis was also piloted at the planning area level. The results presented indicate a range of potential water demand changes across sectors and regions under different scenarios and climate change impacts.

1. 1Integrated Scenario Analysis for the California Water Plan Update 2009Rich Juricich, DWRMohammad Rayej, DWRDavid Groves, RANDDavid Yates, NCARDavid Purkey, SEIBrian Joyce, SEIAndy Draper, MWH

2. Presentation OverviewWater Plan Highlights and climate change Scenario concepts used in California Water PlanApplication of scenarios to statewide Hydrologic RegionsSummary of climate information in Water Plan Update 20092

3. 3Climate Change: Stressing Our Water System (1)

4. 4Average Annual Snowmelt Projections

5. 5Projected Decrease in CA Snowmelt

6. 6Historical & Projected Sea Level at GG

7. 7American River RunoffAnnual Maximum 3-Day Flow

8. 8Scenario Concepts

9. Water Plan Scenarios Used ToConsider Future UncertaintyThree plausible yet very different conditions during 2050 planning horizonExplore key uncertainties facing water communityFactors water community has little control overNot predictions ---- used to evaluate water management responses9

10. Scenarios Organized Around UncertaintyEconomic and FinancialInstitutional and PoliticalNatural SystemsTechnologySocialPractices10

11. Evaluating Uncertainty Using ScenariosIndicators(e.g. Supply Reliability)Scenario 1 (with ManagementResponse )Scenario 3 (baseline)Scenario 2 (baseline)Scenario 1 (baseline)Water PortfoliosUncertainties:Future Climate Population GrowthLand Use PatternsEconomic Cycles2050Today11

12. 3 Baseline Scenarios for 2050Plausible Yet Different FuturesRecent trends continue into the future for population, agricultural production, environmental water, and background water conservation

13. More coordinated planning & infill

14. Lower population growth

15. Lower reduction in agricultural production

16. New environment water -- High

17. More background water conservation

18. Less coordinated planning, sprawl

19. Higher population growth

20. Higher reduction in agricultural production

21. New environment water -- Low

22. Less background water conservationCurrent TrendsStrategic GrowthExpansive Growth12

23. Technical Outreach for ScenariosDecember 2007 – Scenario proposalApril 2008 – Shared Vision PlanningJune 2008 – Refinement of scenario proposalClimate changeEnvironmental waterFlood managementWater qualityFebruary 2009 – Review of preliminary demandsJune 2009 – Review of revised results & graphicsJuly 2009 – Climate TAG13

24. Quantifying Future Scenariosfor Update 2009Using WEAP analytical tool to quantify water demand and supplies for future scenarios and water management responsesWEAP Hydrologic Region analysis being done for all regions --- high level, coarse representationWEAP Planning Area analysis for Sacramento and San Joaquin regions --- more physically basedEach scenario evaluated with 12 climate sequences (climate change, multiple year droughts, wet years)14

25. 15Future Precipitation ProjectionsFuture Temperature Projections Local time series of monthly weatherStatistical downscaling methods produce local weather sequences*

26. Weather sequences drive hydrologic models to calculate:

27. irrigation demand (HR and PA)

28. hydrologic flows (PA analysis, only) Hydrologic ModelAnalysis Considers Possible Climate Change ImpactsGlobal circulation models produce numerous projections of future temperature and precipitation patterns