1. 1 Climate Warming & California’s Water Future Jay R. Lund, Richard E. Howitt, Marion W. Jenkins, Tingju Zhu, Stacy K. Tanaka, Manuel Pulido, Melanie Taubert, Randall Ritzema, Inês Ferreira, Sarah Null Civil & Environmental Engineering Agricultural & Resource Economics University of California, Davis http://cee.engr.ucdavis.edu/faculty/lund/CALVIN/

2. 2 Tantalus In Hades, thirsty Tantalus was burdened to have water rise to his neck threatening to drown him, but receded when he stooped to drink. Above him was a boulder, threatening to crush him at some uncertain future time. California’s water managers are similarly tantalized by prospects for quenching California’s thirsts, but contend with floods and droughts, living in a world with grave prospects of earthquakes, budgets, population growth, and climate change.

3. 3 Overview 1)Major Issues 2)2100 Population Changes 3)2100 Climate Changes 4)CALVIN Model 5)Adaptations to the Future 6)Results 7)Conclusions

4. 4 Major Issues Climate warming effects on California’s water supplies. Combined population growth and climate change stress. Could California adapt? How well could California adapt? What would life be like?

5. 5 2100 Population & Land Use 1.Future population and land use will greatly affect water demands. 2.With growth to 92 million (UCB), urban demands grow by ~ 7.2 maf/yr 3.Urbanization of irrigated land reduces agricultural demands by ~ 2.7 maf/yr 4.Net effect is big (+4.5 maf/yr) and economically important

6. 6 2100 Climate Changes 1.Water availability changes estimated for 12 climate warming scenarios (based on LBNL). 2.Water supply impacts estimated for: a.Major mountain inflows b.Groundwater inflows c.Local streams d.Reservoir evaporation 3.Effects estimated for 113 inflows distributed throughout California

7. 7 2100 Climate Changes

8. 8 2100 Raw Water Availability Climate Scenario Average Annual Water Availability Climate Scenario Average Annual Water Availability Vol. maf Change maf Volume maf Change maf 1) 1.5T 0%P35.7 -2.1 7) HCM 202541.94.1 2) 1.5T 9%P37.7 -0.1 8) HCM 206540.52.7 3) 3.0T 0%P33.7 -4.1 9) HCM 210042.44.6 4) 3.0T 18%P37.1 -0.810) PCM 202535.7-2.1 5) 5.0T 0%P31.6 -6.211) PCM 206532.9-4.9 6) 5.0T 30%P36.2 -1.612) PCM 210028.5-9.4 Historical37.8 0.0

9. 9 What is CALVIN Model? Entire inter-tied California water system Surface and groundwater systems; supply and demands Economics-driven optimization model Economic Values for Agricultural, Urban, & Hydropower Uses Flow Constraints for Environmental Uses Prescribes monthly system operation over a 72-year representative hydrology Maximizes economic performance within constraints

10. 10 Over 1,200 spatial elements 51 Surface reservoirs 28 Ground water reservoirs 24 Agricultural regions 19 Urban demand regions 600+ Conveyance Links CALVIN’s Spatial Coverage

11. 11 Economic Values for Water Agricultural : Production model SWAP Urban : Demand model based on price elasticities Hydropower Operating Costs: Pumping, treatment, water quality, etc. Environmental flows and deliveries as constraints – with first priority

12. 12 Data Flow for the CALVIN Model

13. 13 Model Limitations 1) Data: Base hydrology, Tulare Basin, monthly agricultural demands, etc. 2) Network flow formulation, simplified costs, water quality, environmental requirements, hydraulics, hydrologic foresight and coordination 3) Limited range of benefits No flood control or recreation

14. 14 Integrated Adaptation Options Water allocation (markets?) System operations Conjunctive use Coordinated operations Urban conservation/use efficiencies Cropping changes and fallowing Agricultural water use efficiencies New technologies Wastewater reuse Seawater desalination

15. 15 Alternative Conditions 1) Base 2020 – Current policies for 2020 2) SWM 2020 – Statewide water market 2020 3) SWM 2100 – SWM2020 with 2100 demands 4) PCM 2100 – SWM2100 with dry warming 5) HCM 2100 – SWM2100 with wet warming

16. 16 Climate Scenarios by Region

17. 17 Some Early Results Delivery, Scarcity, and Economic Performance Conjunctive Use and other Operations New Technologies Costs of Environmental Flows Flood Frequency Hydropower Performance Economic Value of Facility Changes

18. 18 Scarcity, Operating, & Total Costs ($ million/yr) Cost Base 2020 SWM 2020 SWM 2100 PCM 2100 HCM 2100 Urban Scarcity1,564170785872782 Agric. Scarcity32291981,774180 Operating2,5812,5805,9186,0655,681 Total Costs4,1762,7806,9028,7116,643

19. 19 Total Deliveries and Scarcities

20. 20 Agricultural Deliveries & Scarcities

21. 21 Scarcity Costs by Sector

22. 22 Groundwater Operations

23. 23 Conjunctive Use

24. 24 New Source Technologies

25. 25 Environmental Flow Costs

26. 26 Trinity River Shadow Costs

27. 27 Annual Flood Frequency (Lower American River)

28. 28 Hydropower Generation

29. 29 Economic Value of Facility Changes ($/unit-yr)

30. 30 Conclusions from Results 1)Important to look at climate change impacts and adaptation in context of future water demands, and the entire range of water sources, facilities, and adaptation options. Must also allow adaptations – Optimization. 2)Climate warming’s hydrologic effects are substantiated and generalized. Magnitude comparable to water demand growth. 3)California’s system can adapt, at some cost.

31. 31 Conclusions from Results (con’t) 4)Central Valley agriculture is most sensitive to dry climate warming. 5)Southern California urban users are not very sensitive to climate warming. 6)Adaptation would be challenging. Institutional change and flexibility needed to respond to both population and climate changes. 7)Study limitations are considerable, but it behooves us to consider management and policy changes.

32. 32 Glimpse at Long-term Future Results provides a hazy glimpse at the future of California water management: 1)Integrated mix of many management options: Water use efficiency, conjunctive use, water transfers, reuse, desalination, … 2)Importance of local and regional actions in a statewide context 3)Long-term importance of flexibility 4)Some scarcity is optimal

33. 33 Work left to do… 1)CALVIN improvements 2)Flood penalties 3)Sea level rise 4)Agronomic and land use effects in agricultural demands 5)Better hydrology 6)Hydropower and energy cost improvements http://cee.engr.ucdavis.edu/faculty/lund/CALVIN/