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Climate Warming & California’s Water Future

Jay R. Lund

Civil and Environmental Engineering

University of California, Davis

http://cee.engr.ucdavis.edu/faculty/lund/CALVIN/

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Overview

A. Forms of Climate Change

B. Climate Warming and Water System Performance

C. Concluding thoughts

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Forms of Climate Change

1. Sea level rise

2. Climate warming

3. Climate oscillations

4. Multi-decade droughts

5. Others?

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Climate Warming & Water System Performance

1. 2100 water availability (LBNL)

2. Water management model for climate warming extremes

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Inflows with Climate Warming

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

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1.5T 0%P 1.5T 9%P3.0T 0%P 3.0T 18%P5.0T 0%P 5.0T 30PHCM 2010-2039 HCM 2050-2079HCM 2080-2099 PCM 2010-2039PCM 2050-2079 PCM 2080-2099Historical

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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

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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

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Water Management Objectives

Environmental flows - first priority

Economic Water Uses:– Agricultural economic values

– Urban economic demands (residential, industrial, and commercial)

– Hydropower benefits

– Operating Costs

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2100 Water Availability Extremes (maf/yr)

Average Scenario Availability Change Historical 37.8 0 Dry Warming (PCM) 28.5 -9.4 Wet Warming (HCM) 42.4 4.6

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Climate Scenarios by Region

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Historical

Dry (PCM2100)

Wet (HCM2100)

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Some Early Results

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Total Deliveries and Scarcities

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Upper Sac L.Sac&BayDelta S.Joaq&So.Bay Tulare So.Cal Statewide

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Statewide Economic Costs($ million/yr)

Cost Base 2020

SWM 2020

SWM 2100

Dry 2100

Wet 2100

Urban Scarcity 1,564 170 785 872 782

Agric. Scarcity 32 29 198 1,774 180

Operating 2,581 2,580 5,918 6,065 5,681

Total Costs 4,176 2,780 6,902 8,711 6,643

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Scarcity Costs by Sector

1564

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Base2020 SWM2020 SWM2100 Dry 2100 Wet 2100

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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.

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Economic Value of Facility Changes

($/unit-yr)Reservoir (taf) SWM2100 Dry Wet Turlock 69 202 56 Pardee 68 202 56 Pine Flat 66 198 56 New Bullards Bar 65 196 56 Los Vaqueros 64 186 53

Canal (taf/mo) Putah S. Canal 7378 7611 6528 Mokelumne Aqued. 7180 7609 6301 Coachella Canal 3804 3487 3618 Friant Kern Canal 1733 1960 3585 Colorado Aqueduct 1063 970 759 California Aqueduct 669 1823 452

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Environmental Flow Costs Average Cost ($/af)

Minimum Flows SWM2100 Dry 2100 Wet 2100 Trinity River 45 1011 29

Sac. R. at Keswick 4 665 3 Mokelumne River 21 332 0

Yuba River 0 2 1 Merced River 17 70 1

Mono Lake Inflows 1254 1301 64 Owens Dust Mitigation 1019 1046 3

Refuges Sac West Refuge 11 23 0

Volta Refuges 38 311 21 SJ/Mendota Refuges 33 250 11

Kern 57 377 36 Delta Outflow 10 229 0

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Conclusions from Results1) 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.

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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.