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. 1 Integrated Scenario Analysis for the California Water Plan Update 2009 Rich Juricich, DWR Mohammad Rayej, DWR David Groves, RAND David Yates, NCAR David Purkey, SEI Brian Joyce, SEI Andy Draper, MWH

2. Presentation Overview Water Plan Highlights and climate change Scenario concepts used in California Water Plan Application of scenarios to statewide Hydrologic Regions Summary of climate information in Water Plan Update 2009 2

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

4. 4 Average Annual Snowmelt Projections

5. 5 Projected Decrease in CA Snowmelt

6. 6 Historical & Projected Sea Level at GG

7. 7 American River RunoffAnnual Maximum 3-Day Flow

8. 8 Scenario Concepts

9. Water Plan Scenarios Used ToConsider Future Uncertainty Three plausible yet very different conditions during 2050 planning horizon Explore key uncertainties facing water community Factors water community has little control over Not predictions ---- used to evaluate water management responses 9

10. Scenarios Organized Around Uncertainty Economic and Financial Institutional and Political Natural Systems Technology Social Practices 10

11. Evaluating Uncertainty Using Scenarios Indicators (e.g. Supply Reliability) Scenario 1 (with Management Response ) Scenario 3 (baseline) Scenario 2 (baseline) Scenario 1 (baseline) Water Portfolios Uncertainties: Future Climate Population Growth Land Use Patterns Economic Cycles 2050 Today 11

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 Trends Strategic Growth Expansive Growth 12

23. Technical Outreach for Scenarios December 2007 – Scenario proposal April 2008 – Shared Vision Planning June 2008 – Refinement of scenario proposal Climate change Environmental water Flood management Water quality February 2009 – Review of preliminary demands June 2009 – Review of revised results & graphics July 2009 – Climate TAG 13

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

26. Weather sequences drive hydrologic models to calculate:

27. irrigation demand (HR and PA)

29. Six GCMs

30. Two global emissions scenarios * Using the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset

31. Hydrologic Region Scale Analysis 16

32. Hydrologic Region Analysis Monthly, climate-driven demands to 2050 reflect global climate change projections Agriculture, Urban, and Environmental sectors Simple representation of supplies possible 17 All 10 Hydrologic Regions

33. Framework for Statewide Scenarios Response packages evaluated using Planning Area model for select Hydrologic Regions New! New! Supply and environmental flows addressed using Planning Area model 18

34. 19 Water Scenarios 2050: Range of Considerations

35. 20 3 Future Scenarios: Key Factors of Uncertainty

36. 21 Legend: Water Demand Changes& Climate Change Variability

37. 22 2050 Water Demand Changes by Sector & Scenario

38. Climate change increases variability and range of future statewide water demands 23

39. Regional Water Demand Changes by Scenario 24

40. Planning Area AnalysisSacramento and San Joaquin River Regions Hydrologically-based water system simulation by month to 2050 reflect global climate change projections Estimate environmental flows, system operations, deliveries, and reliability More direct representation of response packages 25 Sacramento River San Joaquin River Sacramento River & San Joaquin River Hydrologic Regions

41. Climate Information in Update 2009 Highlights Volume 1 Chapter 4 – California Water Today Chapter 5 – Managing an Uncertain Future Chapter 6 – Integrated Data and Analysis Volume 4 Reference guide Climate Adaptation Strategy Climate Science 26

42. Summary Water Plan uses scenarios to capture future uncertainties like population growth, land use changes, and climate change Water Plan shows water demands out to 2050 using 3 scenarios and 12 climate sequences As part of Update 2009 we have piloted finer detail analysis at Planning Area scale Pre-Final draft of Water Plan is available on-line and contains a wealth of information on California water management. 27

43. Reference Information Rich Juricich juricich@water.ca.gov (916) 651-9225 Water Plan Update 2009 http://www.waterplan.water.ca.gov/cwpu2009 SWAN http://www.waterplan.water.ca.gov/swan 28