1

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 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.

How like California water management!

3

Change

"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.

4

Overview

1. Climate Change in California Historical, Pre-historical, Future

2. Adaptation to Climate Warming Warming and water demand scenarios

Options for adaptation

Analysis for promising adaptations and performance

3. Conclusions

5

Historical climate variability

Roughly 100 years of record

Two 6-year droughts

One 2-year drought

Other odd dry years

Correlation of droughts with Pacific Decadal Oscillation (PDO) – Scripps, and others

6

Pre-historical variability1) Last 1,000 years

a) Scott Stine - Lake with long droughts

b) Meko – Streamflow fluctuations – tree rings

c) 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 sediments

b) Tahoe reaches sill 3,000 years ago

7

Past sea level rise

Steady long-term rise since Ice Age’s end

Delta is a drowned river valley, < 10,000 years old

California has always been a dynamic place?

8

Future Climate Changes

1) Sea level rise

2) Climate Variability

3) Climate Warming

4) Other forms of climate change?

9

Future sea level rise Certain occurrence Rate is significant, but somewhat

uncertain (about 1ft/century?)

Some coastal implications

Potential Delta water quality and flooding implications in 50-100 years (Anderson)

10

Future Climate Variability

Almost certain to continue.

El Nino Southern Oscillation – ENSO

Pacific Decadal Oscillation – PDO

Other forms of variability?

11

Climate Warming1) Seems very likely

2) Some effects already seen in California?

Earlier snowmelt in recent decades

Is it greenhouse warming or PDO change?

3) Wet or dry warming?

4) CO2 and other changes…

12

Climate Warming Effects?

1) Shift in snowmelt season

2) Changes in: Crop ETAW and yields

Watershed and reservoir ET

Urban water use

Ecosystems (T, nutrients, CO2, etc.)

3) Wet or dry warming?

Some changes are clear, others uncertain.

13

Other forms of climate change?

Who knows? Varying solar intensity, …

Still a new subject.

How will different forms of climate change combine?

14

Conclusions about climate change

California’s climate has always changed

Maybe last century was lucky

Additional climate changes seem likely

Changes will affect water system operations

Would changes affect system performance?

How can our water system adapt?

15

Climate Warming and Water Management

Preliminary study of climate warming for water management in California

2100 climate warming and population growth scenarios

CALVIN model identifies promising adaptations to climate and population changes

Preliminary results

Conclusions

Thanks to California Energy Commission for funding!

16

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

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 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

18

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

19

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

20

• 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

What is CALVIN?

21

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

22

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

23

Data Flow for the CALVIN Model

24

Integrated Adaptation Options

• 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

25

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

26

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

27

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

28

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

29

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

30

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

31

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

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

An

nu

al

Av

era

ge

Pe

na

lty

($

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

un

dw

ate

r S

tora

ge

(m

af/

mo

n)

Base2020 SWM2020 SWM2100

PCM2100 HCM2100

34

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

35

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

36

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

37

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

)

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

Av

era

ge

d F

loo

d F

low

(c

fs)

Historical Record

HCM 2090

PCM 2090

39

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

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 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

41

Conclusions from Results

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.

42

Conclusions from Results (con’t)

5) Central Valley agriculture sensitive to dry warming

6) Urban S. Calif. less sensitive to warming

7) 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.

43

Glimpse at Long-term Future1) 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/