1 Climate Warming & California’s Water Future Jay R. Lund Civil and Environmental Engineering University of California, Davis

2 Overview A.Forms of Climate Change B.Climate Warming and Water System Performance C.Concluding thoughts

3 Forms of Climate Change 1.Sea level rise 2.Climate warming 3.Climate oscillations 4.Multi-decade droughts 5.Others?

4 Climate Warming & Water System Performance water availability (LBNL) 2.Water management model for climate warming extremes

5 Inflows with Climate Warming

6 Over 1,200 spatial elements 51 Surface reservoirs 28 Ground water reservoirs 600+ Conveyance links 88% of irrigated acreage 92% of population CALVIN’s Spatial Coverage

7 Integrated Adaptation Options Water allocation and markets Joint surface & groundwater operations Coordinated facility operations Urban conservation/use efficiencies Cropping changes and fallowing Agricultural water use efficiencies New technologies Wastewater reuse Seawater desalination

8 Water Management Objectives Environmental flows - first priority Economic Water Uses: –Agricultural economic values –Urban economic demands (residential, industrial, and commercial) –Hydropower benefits –Operating Costs

Water Availability Extremes (maf/yr)

10 Climate Scenarios by Region

11 Some Early Results

12 Total Deliveries and Scarcities

13 Statewide Economic Costs ($ million/yr)

14 Scarcity Costs by Sector

15 Adaptive Responses Water transfers Agricultural to urban Colorado River Central Valley Water quality exchanges Flexibility trading New technologies Wastewater reuse Sea water desalination Urban water conservation/use efficiencies Groundwater reservoir use The mix of responses is important.

16 Economic Value of Facility Changes ($/unit-yr)

17 Environmental Flow Costs

18 Conclusions from Results 1)Climate warming can be wetter or drier overall, with seasonal flow shifts. 2)Central Valley agriculture is most sensitive to dry climate warming. 3)Flooding could be very challenging and costly. 4)California’s system can adapt, at some cost, if it has institutional flexibility.

19 What to do now? 1)Long-term importance of flexibility 2)Integrated mix of management options: Water use efficiency, conjunctive use, water transfers, reuse, desalination, storage … 3)Importance of local and regional actions in a statewide context 4)Enhance ability to cooperate at local, regional, and statewide levels to gain from the richness and strengths of our water system.