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/
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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?
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Future Climate Changes
1) Sea level rise
2) Climate Variability
3) Climate Warming
4) Other forms of climate change?
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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)
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Future Climate Variability
Almost certain to continue.
El Nino Southern Oscillation – ENSO
Pacific Decadal Oscillation – PDO
Other forms of variability?
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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…
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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?
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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?
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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!
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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
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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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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
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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
What is CALVIN?
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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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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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Data Flow for the CALVIN Model
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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
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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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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
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
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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 (
$/af
)
38
Annual Flood Frequency(Lower American River)
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
0% 20% 40% 60% 80% 100%
Annual Exceedence Probability
3-D
ay
Av
era
ge
d F
loo
d F
low
(c
fs)
Historical Record
HCM 2090
PCM 2090
39
Hydropower Generation
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
200001
92
2
19
26
19
30
19
34
19
38
19
42
19
46
19
50
19
54
19
58
19
62
19
66
19
70
19
74
19
78
19
82
19
86
19
90
An
nu
al
En
erg
y G
en
era
tio
n (
GW
hr/
yr)
Base2020 SWM2100 PCM2100 HCM2100
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Economic Value of Facility Changes
($/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 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.
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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.
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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/