Climate Change &California’s Water Future

Jay R. Lund, Tingju Zhu, Stacy K. Tanaka, Marion W. Jenkins, Richard E. Howitt, Manuel Pulido,

Melanie Taubert, Randall Ritzema, Inês Ferreira, Sarah Null

Civil & Environmental EngineeringAgricultural & Resource Economics

University of California, Davis

1http://cee.engr.ucdavis.edu/faculty/lund/CALVIN/

Tantalus

2

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.

How like California water management!

Change

3

"Change has considerable psychological impact …. To the fearful it is threatening because …things may get worse. To the hopeful it is encouraging because things may get better. To the confident it is inspiring because the challenge exists to make things better. … One’s character and frame of mind determine how readily he brings about change and how he reacts to change that is imposed on him." - King Whitney Jr.

Overview

4

1. Climate Change in CaliforniaHistorical, Pre-historical, Future

2. Adaptation to Climate WarmingWarming and water demand scenarios Options for adaptationAnalysis for promising adaptations and performance

3. Conclusions

Historical climate variability

5

Roughly 100 years of recordTwo 6-year droughtsOne 2-year droughtOther odd dry yearsCorrelation of droughts with Pacific Decadal Oscillation (PDO) – Scripps, and others

Pre-historical variability

6

1) Last 1,000 yearsa) Scott Stine - Lake with long droughts b) Meko – Streamflow fluctuations – tree ringsc) Others – Long term lake fluctuations – PDO

connection for some droughts

2) Earlier Holocene (10,000 years)a) Multi-decade and Multi-century droughts –

lake and estuary sedimentsb) Tahoe reaches sill 3,000 years ago

Past sea level rise

7

Steady long-term rise since Ice Age’s endDelta is a drowned river valley, < 10,000 years old

California has always been a dynamic place?

Future Climate Changes

8

1) Sea level rise

2) Climate Variability

3) Climate Warming

4) Other forms of climate change?

Future sea level rise

9

Certain occurrenceRate is significant, but somewhat uncertain (about 1ft/century?)

Some coastal implicationsPotential Delta water quality and flooding implications in 50-100 years (Anderson)

Future Climate Variability

10

Almost certain to continue.

El Nino Southern Oscillation – ENSOPacific Decadal Oscillation – PDOOther forms of variability?

Climate Warming

11

1) Seems very likely

2) Some effects already seen in California?

Earlier snowmelt in recent decadesIs it greenhouse warming or PDO change?

3) Wet or dry warming?

4) CO2 and other changes…

Climate Warming Effects?

12

1) Shift in snowmelt season

2) Changes in:Crop ETAW and yieldsWatershed and reservoir ETUrban water useEcosystems (T, nutrients, CO2, etc.)

3) Wet or dry warming?Some changes are clear, others uncertain.

Other forms of climate change?

13

Who knows?Varying solar intensity, …

Still a new subject.

How will different forms of climate change combine?

Conclusions about climate change

14

California’s climate has always changedMaybe last century was luckyAdditional climate changes seem likelyChanges will affect water system operations

Would changes affect system performance?How can our water system adapt?

Climate Warming and Water Management

Preliminary study of climate warming for water management in California2100 climate warming and population growth scenarios CALVIN model identifies promising adaptations to climate and population changesPreliminary resultsConclusions

Thanks to California Energy Commission for funding!15

2100 Climate Changes

16

1. Water availability changes estimated for 12 climate warming scenarios (based on LBNL).

2. Water supply impacts estimated for:a. Major mountain inflowsb. Groundwater inflowsc. Local streamsd. Reservoir evaporation

3. Effects estimated for 113 inflows distributed throughout California

17

2100 Climate Changes

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1 2 3 4 5 6 7 8 9 10 11 12

Calendar Month

Tota

l Mon

thly

Mea

n R

im In

flow

(TA

F)

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

2100 Raw Water Availability

18

Climate Scenario

Average Annual Water Availability Climate

Scenario

Average Annual Water Availability

Vol. maf

Changemaf

Volume maf

Changemaf

1) 1.5T 0%P 35.7 -2.1 7) HCM 2025 41.9 4.1

2) 1.5T 9%P 37.7 -0.1 8) HCM 2065 40.5 2.7

3) 3.0T 0%P 33.7 -4.1 9) HCM 2100 42.4 4.6

4) 3.0T 18%P 37.1 -0.8 10) PCM 2025 35.7 -2.1

5) 5.0T 0%P 31.6 -6.2 11) PCM 2065 32.9 -4.9

6) 5.0T 30%P 36.2 -1.6 12) PCM 2100 28.5 -9.4

Historical 37.8 0.0

2100 Population & Land Use

19

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

What is CALVIN?

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• Model of 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

21

Over 1,200 spatial elements51 Surface reservoirs 28 Ground water reservoirs600+ Conveyance Links 88% of irrigated acreage92% of population

CALVIN’s Spatial Coverage

Economic Values for Water

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• 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

Data Flow for the CALVIN Model

Databases of Input & Meta- Data

HECPRM Solution Model

Surface and ground water hydrology

Environmental flow constraints

Urban values of water (elasticities)

Agricultural values of water (SWAP)

Physical facilities & capacities

Values of increased facility capacities

Conjunctive use & cooperative operations

Water operations & delivery reliabilities

Willingness-to-pay for additional water & reliability

Value of more flexible operations

Economic benefits of alternatives

Operating costs

CALVIN Economic Optimization Model:

23

Integrated Adaptation Options

24

• Water allocation (markets & exchanges)• System operations

• Conjunctive use• Coordinated operations

• Urban conservation/use efficiencies• Cropping changes and fallowing• Agricultural water use efficiencies• New technologies

• Wastewater reuse• Seawater desalination

Model Limitations1) Data:

Base hydrology, Tulare Basin, monthly agricultural demands, etc.

2) Network flow formulation, simplifiedcosts, water quality, environmental requirements, hydraulics, hydrologic foresight and coordination

3) Limited range of benefitsNo flood control or recreation

25

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

26

Climate Scenarios by Region

27

11.3

15.6

8.49.9

4.5

8.8

11.8

6.4

8.5

4.2

17.6

26.6

15.216.5

4.9

0

5

10

15

20

25

30

Upper Sac. L.Sac&BayDelta S.Joaq&S.Bay Tulare So.CalAcc

retio

ns -

Dep

letio

ns +

Rim

Inflo

ws

+ G

roun

dwat

er In

flow

s - R

eser

voir

Evap

(maf

/yr)

Historical PCM2100 HCM2100

Some Early Results

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• 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

Scarcity, Operating, & Total Costs($ million/yr)

CostBase 2020

SWM2020

SWM2100

PCM2100

HCM2100

Urban Scarcity 1,564 170 785 872 782

Agric. Scarcity 32 29 198 1,774 180Operating 2,581 2,580 5,918 6,065 5,681Total Costs 4,176 2,780 6,902 8,711 6,643

29

30

Total Deliveries and Scarcities

0

5

10

15

20

25

30

35

40

45

50Ba

se20

20SW

M20

20SW

M21

00PC

M21

00H

CM

2100

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Ann

ual A

vera

ge D

eliv

ery

and

Scar

city

(maf

/yr) Scarcity

Deliveries

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

31

Agricultural Deliveries & Scarcities

0

5

10

15

20

25

30Ba

se20

20SW

M20

20SW

M21

00PC

M21

00H

CM

2100

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Base

2020

SWM

2020

SWM

2100

PCM

2100

HC

M21

00

Ann

ual A

vera

ge A

gric

ultu

ral D

eliv

ery

and

Scar

city

(maf

/yr)

Scarcity

Deliveries

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

32

Scarcity Costs by Sector

1564

32

170

29

785

198

872

1774

782.1

179.7

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Total Urban Total Agriculture

Ann

ual A

vera

ge P

enal

ty ($

M/y

r)

Base2020 SWM2020 SWM2100 PCM2100 HCM2100

33

Groundwater Operations

480

490

500

510

520

530

540

550O

ct-2

1

Oct

-24

Oct

-27

Oct

-30

Oct

-33

Oct

-36

Oct

-39

Oct

-42

Oct

-45

Oct

-48

Oct

-51

Oct

-54

Oct

-57

Oct

-60

Oct

-63

Oct

-66

Oct

-69

Oct

-72

Oct

-75

Oct

-78

Oct

-81

Oct

-84

Oct

-87

Oct

-90

Gro

undw

ater

Sto

rage

(maf

/mon

)

Base2020 SWM2020 SWM2100PCM2100 HCM2100

34

Conjunctive Use

0%

10%

20%

30%

40%

50%

60%

0% 20% 40% 60% 80% 100%Annual Exceedence Probability

Tota

l Ann

ual S

uppl

y - %

Gou

ndw

ater

Base2020 SWM2020 SWM2100 PCM2100 HCM2100

35

New Source Technologies

0

200

400

600

800

1,000

1,200

1,400

1,600

1,80019

22

1925

1928

1931

1934

1937

1940

1943

1946

1949

1952

1955

1958

1961

1964

1967

1970

1973

1976

1979

1982

1985

1988

1991

Tota

l Vol

ume

of D

esal

inat

ion

or R

euse

(taf

/yr)

SWM2100-Reuse SWM2100-Desal

PCM2100-Reuse PCM2100-Desal

HCM2100-Reuse HCM2100-Desal

Environmental Flow Costs

36

Average WTP ($/af) Minimum Instream Flows SWM2020 SWM2100 PCM2100 HCM2100

Trinity River 0.6 45.4 1010.9 28.9 Sac. R. at Keswick 0.1 3.9 665.2 3.2 Mokelumne River 0.1 20.7 332.0 0.0

Yuba River 0.0 0.0 1.6 1.0 Merced River 0.7 16.9 70.0 1.2

Mono Lake Inflows 819.0 1254.5 1301.0 63.9 Owens Lk. Dust Mitigation 610.4 1019.1 1046.1 2.5

Refuges Sac West Refuge 0.3 11.1 231.0 0.1

SJ/Mendota Refuges 14.7 32.6 249.7 10.6 Pixley Refuge 24.8 50.6 339.5 12.3 Kern refuge 33.4 57.0 376.9 35.9

Delta Outflow 0.1 9.7 228.9 0.0

37

Trinity River Shadow Costs

0

20

40

60

80

100

120

140

160

180

200

1921 1931 1941 1951 1961 1971 1981 1991Time

Non

-PC

M21

00 S

hado

w C

osts

of I

nstr

eam

Flo

w ($

/af)

0

400

800

1,200

1,600

2,000SWM2020 SWM2100 HCM2100 PCM2100

PCM

2100

Sha

dow

Cos

ts o

f Ins

trea

m F

low

($/a

f)

38

Annual Flood Frequency(Lower American River)

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

0% 20% 40% 60% 80% 100%Annual Exceedence Probability

3-D

ay A

vera

ged

Floo

d Fl

ow (c

fs)

Historical Record

HCM 2090

PCM 2090

39

Hydropower Generation

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18000

2000019

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1926

1930

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1942

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1950

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1966

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1974

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1982

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1990

Ann

ual E

nerg

y G

ener

atio

n (G

Whr

/yr)

Base2020 SWM2100 PCM2100 HCM2100

40

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

Surface Reservoir (taf) SWM2100 PCM HCM Turlock Reservoir 69 202 56 Santa Clara Aggregate 69 202 56 Pardee Reservoir 68 202 56 Pine Flat Reservoir 66 198 56 New Bullards Bar Reservoir 65 196 56 Conveyance (taf/mo) Lower Cherry Creek Aqueduct 7886 8144 7025All American Canal 7379 7613 6528Putah S. Canal 7378 7611 6528Mokelumne Aqueduct 7180 7609 6301Coachella Canal 3804 3487 3618Colorado Aqueduct 1063 970 759 California Aqueduct 669 1823 452

Conclusions from Results

41

1) Climate warming’s hydrologic effects are substantiated and generalized.

2) Future water demands matter too! Similar magnitude to climate warming effects.

3) Must also allow future adaptations –Optimization.

4) California’s system can adapt, at some cost.

Conclusions from Results (con’t)

42

5) Central Valley agriculture sensitive to dry warming

6) Urban S. Calif. less sensitive to warming7) Flooding problems8) Adaptation would be challenging

Institutional flexibility needed to respond to both population and climate changes.

9) Study has limitations. But it is worthwhile considering management and policy changes.

Glimpse at Long-term Future

43

1) Integrated mix of 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.

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