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/
1
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!
2
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.
3
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
4
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
5
Pre-historical variability
1) 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
6
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?
7
Future Climate Changes
1) Sea level rise
2) Climate Variability
3) Climate Warming
4) Other forms of climate change?
8
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)
9
Future Climate Variability
Almost certain to continue.
 El Nino Southern Oscillation – ENSO
 Pacific Decadal Oscillation – PDO
 Other forms of variability?
10
Climate Warming
1) 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…
11
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.
12
Other forms of climate change?
 Who knows?
 Varying solar intensity, …
 Still a new subject.
 How will different forms of climate
change combine?
13
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?
14
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!
15
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
16
2100 Climate Changes
9000
1.5T 0%P
3.0T 0%P
5.0T 0%P
HCM 2010-2039
HCM 2080-2099
PCM 2050-2079
Historical
Total Monthly Mean Rim Inflow (TAF)
8000
7000
1.5T 9%P
3.0T 18%P
5.0T 30P
HCM 2050-2079
PCM 2010-2039
PCM 2080-2099
6000
5000
4000
3000
2000
1000
0
1
2
3
4
5
6
7
Calendar Month
8
9
10
11
12
17
2100 Raw Water Availability
Climate
Scenario
Average Annual
Water Availability
Vol.
Change
maf
maf
Climate
Scenario
Average Annual
Water Availability
Volume
Change
maf
maf
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
37.8
0.0
Historical
18
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
19
What is CALVIN?
• 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
20
CALVIN’s Spatial Coverage
Over 1,200 spatial elements
51 Surface reservoirs
28 Ground water reservoirs
600+ Conveyance Links
88% of irrigated acreage
92% of population
21
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
22
Data Flow for the CALVIN Model
Surface and
ground water
hydrology
Physical facilities
& capacities
Environmental
flow constraints
Urban values of
water (elasticities)
Agricultural
values of water
(SWAP)
Operating costs
Economic benefits
of alternatives
CALVIN Economic
Optimization Model:
Databases HECPRM
of Input &
Solution
Meta- Data Model
Conjunctive use &
cooperative
operations
Willingness-to-pay
for additional
water & reliability
Water operations
& delivery
reliabilities
Value of more
flexible operations
Values of
increased facility
capacities
23
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
24
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
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
Accretions - Depletions + Rim Inflows + Groundwater Inflows
- Reservoir Evap (maf/yr)
Climate Scenarios by Region
30
26.6
Historical
PCM2100
HCM2100
25
20
17.6
16.5
15.6
15.2
15
11.8
11.3
9.9
10
8.8
8.5
8.4
6.4
4.5 4.2 4.9
5
0
Upper Sac.
L.Sac&BayDelta
S.Joaq&S.Bay
Tulare
27
So.Cal
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
28
Scarcity, Operating, & Total Costs
($ million/yr)
Cost
Base
2020
SWM
2020
SWM
2100
PCM
2100
HCM
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
29
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Scarcity
40
Deliveries
Upper Sac
L.Sac&BayDelta
S.Joaq&So.Bay
Tulare
So.Cal
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
45
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Annual Average Delivery and Scarcity (maf/yr)
Total Deliveries and Scarcities
50
35
30
25
20
15
10
5
0
30
Statewide
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Upper Sac
L.Sac&BayDelta
S.Joaq&So.Bay
Tulare
So.Cal
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
Annual Average Agricultural Delivery and Scarcity (maf/yr)
Agricultural Deliveries & Scarcities
30
25
Scarcity
Deliveries
20
15
10
5
0
31
Statewide
Scarcity Costs by Sector
2000
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
1800
Annual Average Penalty ($M/yr)
1600
1774
1564
1400
1200
1000
872
785
800
782.1
600
400
200
198
170
32
29
0
Total Urban
179.7
Total Agriculture
32
Oct-87
Oct-84
Oct-81
Oct-78
Oct-75
33
Oct-90
SWM2020
HCM2100
Oct-72
Oct-69
Oct-66
Oct-63
Oct-60
Oct-57
Base2020
PCM2100
Oct-54
Oct-51
Oct-48
Oct-45
Oct-42
Oct-39
Oct-36
Oct-33
Oct-30
Oct-27
Oct-24
Oct-21
Groundwater Storage (maf/mon)
Groundwater Operations
550
540
530
520
510
500
490
SWM2100
480
Conjunctive Use
Total Annual Supply - %Goundwater
60%
50%
40%
30%
20%
10%
Base2020
SWM2020
SWM2100
PCM2100
HCM2100
0%
0%
20%
40%
60%
Annual Exceedence Probability
80%
100%
34
HCM2100-Reuse
HCM2100-Desal
35
1991
PCM2100-Desal
1988
PCM2100-Reuse
1985
SWM2100-Desal
1982
SWM2100-Reuse
1979
1976
1973
1970
1967
1964
1961
1958
1955
1952
600
1949
800
1946
1943
1940
1937
1934
1931
1928
1925
1922
Total Volume of Desalination or Reuse (taf/yr)
New Source Technologies
1,800
1,600
1,400
1,200
1,000
400
200
0
Environmental Flow Costs
Minimum Instream Flows
Trinity River
Sac. R. at Keswick
Mokelumne River
Yuba River
Merced River
Mono Lake Inflows
Owens Lk. Dust Mitigation
Refuges
Sac West Refuge
SJ/Mendota Refuges
Pixley Refuge
Kern refuge
Delta Outflow
SWM2020
0.6
0.1
0.1
0.0
0.7
819.0
610.4
0.3
14.7
24.8
33.4
0.1
Average WTP ($/af)
SWM2100 PCM2100 HCM2100
45.4
1010.9
28.9
3.9
665.2
3.2
20.7
332.0
0.0
0.0
1.6
1.0
16.9
70.0
1.2
1254.5
1301.0
63.9
1019.1
1046.1
2.5
11.1
32.6
50.6
57.0
9.7
231.0
249.7
339.5
376.9
228.9
0.1
10.6
12.3
35.9
0.0
36
Trinity River Shadow Costs
200
2,000
SWM2100
HCM2100
PCM2100
180
160
1,600
140
120
1,200
100
80
800
60
40
400
20
0
1921
0
1931
1941
1951
1961
Time
1971
1981
1991
37
PCM2100 Shadow Costs of Instream Flow ($/af)
Non-PCM2100 Shadow Costs of Instream Flow ($/af)
SWM2020
Annual Flood Frequency
(Lower American River)
3-Day Averaged Flood Flow (cfs)
350,000
300,000
Historical Record
250,000
HCM 2090
200,000
PCM 2090
150,000
100,000
50,000
0
0%
20%
40%
60%
80%
Annual Exceedence Probability
100%
38
1986
1982
1978
39
1990
PCM2100
1974
1970
1966
SWM2100
1962
1958
1954
1950
Base2020
1946
1942
1938
1934
1930
1926
1922
Annual Energy Generation (GWhr/yr)
Hydropower Generation
20000
18000
HCM2100
16000
14000
12000
10000
8000
6000
4000
2000
0
Economic Value of Facility Changes
($/unit-yr)
Surface Reservoir (taf)
SWM2100
Turlock Reservoir
69
Santa Clara Aggregate
69
Pardee Reservoir
68
Pine Flat Reservoir
66
New Bullards Bar Reservoir
65
Conveyance (taf/mo)
Lower Cherry Creek Aqueduct
7886
All American Canal
7379
Putah S. Canal
7378
Mokelumne Aqueduct
7180
Coachella Canal
3804
Colorado Aqueduct
1063
California Aqueduct
669
PCM HCM
202 56
202 56
202 56
198 56
196 56
8144
7613
7611
7609
3487
970
1823
7025
6528
6528
6301
3618
759
452
40
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.
41
Conclusions from Results (con’t)
5) Central Valley agriculture sensitive to dry
warming
6) Urban S. Calif. less sensitive to warming
7) Flooding problems
8) 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.
42
Glimpse at Long-term Future
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/
43