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

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

Overview1) Major Issues

2) 2100 Population Changes

3) 2100 Climate Changes

4) CALVIN Model

5) Adaptations to the Future

6) Results

7) Conclusions

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

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

2100 Climate Changes1. 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

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 Mo

nth

ly M

ean

Rim

Infl

ow

(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

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2100 Raw Water Availability

 

 

 

 

 

 

 

 

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

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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

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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

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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

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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

CALVI N Economic Optimization Model:

Data Flow for the CALVIN Model

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Model Limitations

1) 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

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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

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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

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Climate Scenarios by Region

11.3

15.6

8.4

9.9

4.5

8.8

11.8

6.4

8.5

4.2

17.6

26.6

15.2

16.5

4.9

0

5

10

15

20

25

30

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

reti

on

s -

Dep

leti

on

s +

Rim

In

flo

ws

+ G

rou

nd

wat

er I

nfl

ow

s -

Res

ervo

ir E

vap

(m

af/y

r)

Historical PCM2100 HCM2100

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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

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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 1,774 180

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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Total Deliveries and Scarcities

0

5

10

15

20

25

30

35

40

45

50B

ase

20

20

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

An

nu

al A

vera

ge

Del

iver

y an

d S

carc

ity

(maf

/yr) Scarcity

Deliveries

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

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Agricultural Deliveries & Scarcities

0

5

10

15

20

25

30B

ase

20

20

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

Ba

se2

02

0

SW

M2

020

SW

M2

100

PC

M2

10

0

HC

M2

100

An

nu

al A

vera

ge

Ag

ricu

ltu

ral

Del

iver

y an

d S

carc

ity

(maf

/yr)

Scarcity

Deliveries

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

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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

An

nu

al

Av

era

ge

Pe

na

lty

($

M/y

r)

Base2020 SWM2020 SWM2100 PCM2100 HCM2100

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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

un

dw

ate

r S

tora

ge

(m

af/

mo

n)

Base2020 SWM2020 SWM2100

PCM2100 HCM2100

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Conjunctive Use

0%

10%

20%

30%

40%

50%

60%

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

To

tal A

nn

ual

Su

pp

ly -

%G

ou

nd

wat

er

Base2020 SWM2020 SWM2100 PCM2100 HCM2100

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New Source Technologies

0

200

400

600

800

1,000

1,200

1,400

1,600

1,8001

92

2

19

25

19

28

19

31

19

34

19

37

19

40

19

43

19

46

19

49

19

52

19

55

19

58

19

61

19

64

19

67

19

70

19

73

19

76

19

79

19

82

19

85

19

88

19

91

To

tal V

olu

me

of

De

sa

lin

atio

n o

r R

eu

se

(ta

f/y

r)

SWM2100-Reuse SWM2100-Desal

PCM2100-Reuse PCM2100-Desal

HCM2100-Reuse HCM2100-Desal

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Environmental Flow Costs 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

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Trinity River Shadow Costs

0

20

40

60

80

100

120

140

160

180

200

1921 1931 1941 1951 1961 1971 1981 1991Time

No

n-P

CM

2100

Sh

ado

w C

ost

s o

f In

stre

am F

low

($

/af)

0

400

800

1,200

1,600

2,000SWM2020 SWM2100 HCM2100 PCM2100

PC

M21

00 S

had

ow

Co

sts

of

Inst

ream

Flo

w (

$/af

)

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Annual Flood Frequency(Lower American River)

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Exceedence Probability

Flo

w (

taf/

mo

)

HCM 2100

Historical 2100

PCM 2100

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Hydropower Generation

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

200001

92

2

19

26

19

30

19

34

19

38

19

42

19

46

19

50

19

54

19

58

19

62

19

66

19

70

19

74

19

78

19

82

19

86

19

90

An

nu

al

En

erg

y G

en

era

tio

n (

GW

hr/

yr)

Base2020 SWM2100 PCM2100 HCM2100

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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 7025 All American Canal 7379 7613 6528 Putah S. Canal 7378 7611 6528 Mokelumne Aqueduct 7180 7609 6301 Coachella Canal 3804 3487 3618 Colorado Aqueduct 1063 970 759 California Aqueduct 669 1823 452

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Conclusions from Results1) 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.

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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.

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Glimpse at Long-term FutureResults 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 flexibility4) Some scarcity is optimal

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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/