Managing
Uncertainty:
Evaluating Vulnerabilities
and Resource
Management
Strategies for Three
Hydrologic Regions
David G. Groves (RAND)
California Water Plan Update 2013
January 2015
Slide 1
Analysis Presented in Highlights
Document and Volume 1, Chapter 5
Slide 2
California Water Plan analysis looks
into the uncertain future…
• How vulnerable is California’s water
management system?
• How can the water management
community reduce these
vulnerabilities?
• Builds on the scenario analysis
begun for California Water Plan
2005 Update
• Focuses on Central Valley
• Evaluates plausible futures out to
2050
• Uses new data and tools
Slide 3
Analysis guided by approach called
Robust Decision Making
1. Decision
Structuring
4. Tradeoff
Analysis
New
options
2. Simulation
of Many Futures
3. Vulnerability
Analysis
Robust
strategies
Descriptions of key
vulnerabilities
Slide 4
Study Generated Hundreds of Different
Plausible Futures
What future conditions
might we face?
1. Decision
Structuring
4. Tradeoff
Analysis
New
options
2. Simulation
of Many Futures
3. Vulnerability
Analysis
Robust
strategies
How might the water
management system
perform in different
future scenarios?
Descriptions of key
vulnerabilities
Slide 5
Analysis of the simulations revealed the
drivers of vulnerability
1. Decision
Structuring
4. Tradeoff
Analysis
New
options
2. Simulation
of Many Futures
3. Vulnerability
Analysis
Robust
strategies
Descriptions of key
vulnerabilities
Which factors lead to
vulnerabilities?
How might we
respond to reduce
these vulnerabilities?
Slide 6
Analysis of response packages revealed key
tradeoffs and robust strategies
1. Decision
Structuring
4. Tradeoff
Analysis
How does diversification
increase resilience and
at what cost?
Robust
strategies
New
options
2. Simulation
of Many Futures
3. Vulnerability
Analysis
Descriptions of key
vulnerabilities
Slide 7
Nine land use scenarios reflect uncertain
population growth and land use patters
Three population projections
X
Three density assumptions
Low
Sacramento River, San Joaquin River,
Tulare Lake hydrologic regions
Current
Trends
High
More single
family homes
More multifamily homes
Larger urban
footprint
Smaller urban
footprint
Less irrigated
agricultural
land
More irrigated
agricultural
land
Slide 8
Twenty-two climate scenarios reflect
uncertainty about hydrologic conditions
Downscaled
GCM projections
Historical with
extended drought
and warming
Historical with
extended drought
Slide 9
Performance of water management
system evaluated using four key metrics
Urban reliability
Agricultural reliability
Groundwater levels
Environmental flows
Slide 10
Simulations show range
of plausible future outcomes
Section and region
Results for each
of 198 futures
Middle result
value
Percentage of years in which demand
is sufficiently met
Slide 11
High urban and agricultural reliability in
Sacramento River hydrologic region
Reliability is greater than 90% for
urban and agricultural sector for
all futures
Slide 12
Low agricultural reliability in San Joaquin
River hydrologic region for many plausible
futures
Simulations show agricultural reliability
below 95% for half the futures
Slide 13
Low urban reliability and extremely low
agricultural reliability for many futures in
Tulare Lake hydrologic region
Simulations show low agricultural
reliability for almost all futures
See Figure 5-11, Vol. 1
Slide 14
Wide Range of Groundwater Outcomes—
Declines in Tulare Lake
Average of 2045-2050
minus average of 2005-2010
Slide 15
Which factors lead to urban and
agricultural vulnerabilities?
Vulnerability threshold = 95% reliability
Slide 16
Future climate conditions drive
long-term vulnerabilities
Urban: not vulnerable
Agricultural: not vulnerable
Urban: not vulnerable
Agricultural: 5% precipitation decline and
1 degree F warmer
Urban: 5% precipitation decline and
1.5 degree F warmer – less vulnerable
for high density land use scenarios
Agricultural: All futures that do not have 5% or
more increases
Slide 17
Future climate conditions drive
long-term vulnerabilities
San Joaquin River HR Agricultural Sector
Slide 18
What management strategies can
reduce these vulnerabilities?
Urban water use efficiency
Agricultural water use efficiency
Recycled municipal water
Conjunctive management
New environmental flow targets
Groundwater recovery targets
Slide 19
Response Packages Represent different levels of
strategy diversification over time
Currently Planned Management
Urban
water use
efficiency
+20% efficiency
Agricultural
water use
efficiency
Current
Recycled
municipal
water
Current
Conjunctive
management
Current
Environmental
flow targets
Current
Groundwater
recovery
targets
Cannot drop below historical levels
2010
2020
2030
2040
2050
Slide 20
Response Packages Represent different levels of
strategy diversification over time
Diversification Level 1
Urban
water use
efficiency
+20% efficiency
Agricultural
water use
efficiency
+10% efficiency
Recycled
municipal
water
Current
Conjunctive
management
Current
Environmental
flow targets
Current
Groundwater
recovery
targets
Cannot drop below historical levels
2010
2020
+30% efficiency
2030
2040
2050
Slide 21
Response Packages Represent different levels of
strategy diversification over time
Diversification Level 2
Urban
water use
efficiency
+20% efficiency
Agricultural
water use
efficiency
+10% efficiency
Recycled
municipal
water
+30% efficiency
+50% reuse
Conjunctive
management
Up to 20 TAF/month/planning area banked
Environmental
flow targets
Current
Groundwater
recovery
targets
Cannot drop below historical levels
2010
2020
2030
2040
2050
Slide 22
Response Packages Represent different levels of
strategy diversification over time
Diversification Level 3
Urban
water use
efficiency
+20% efficiency
Agricultural
water use
efficiency
+10% efficiency
Recycled
municipal
water
+30% efficiency
+50% reuse
Conjunctive
management
Up to 20 TAF/month/planning area banked
Environmental
flow targets
Sacramento @ Freeport, Stanislaus AFRP 2; ERP Targets 1 and 2; American River 2
Groundwater
recovery
targets
Higher groundwater minimum targeting no long-term decrease
2010
2020
2030
2040
2050
Slide 23
Response Packages Represent different levels of
strategy diversification over time
Diversification Level 4
Urban
water use
efficiency
+20% efficiency
+30% efficiency
Agricultural
water use
efficiency
+10% efficiency
+15% efficiency
Recycled
municipal
water
+35%
+50% reuse
Conjunctive
management
Up to 40 TAF/month/planning area banked
Environmental
flow targets
Sacramento @ Freeport, Stanislaus AFRP 2; ERP Targets 1 and 2; American River 2
Groundwater
recovery
targets
Higher groundwater minimum targeting no long-term decrease
2010
2020
2030
2040
2050
Slide 24
Response Packages Represent different levels of
strategy diversification over time
Diversification Level 5
Urban
water use
efficiency
+20% efficiency
+30% efficiency
Agricultural
water use
efficiency
+10% efficiency
+20% efficiency
Recycled
municipal
water
+40%
+50% reuse
Conjunctive
management
Up to 40 TAF/month/planning area banked
Environmental
flow targets
Sacramento @ Freeport, Stanislaus AFRP 2; ERP Targets 1 and 2; American River 2
Groundwater
recovery
targets
Higher groundwater minimum targeting no long-term decrease
2010
2020
2030
2040
See Table 5-5, Vol. 1
2050
Slide 25
Response packages affect outcomes
differently across futures
Agricultural Supply and
Urban Supply Reliability
Average Environmental Water
and Change in Groundwater
Increase in
environmental
Water
Agriculture reliability
improvement
Increase in
Groundwater
Urban reliability
improvement
Slide 26
Efficiency, Reuse, and Conjunctive Use
Improves Urban and Agricultural
Reliability
Current
Management
Each dot represents the results for Current Management for one future
Slide 27
Efficiency, Reuse, and Conjunctive
Use Improves Urban and Agricultural
Reliability
Response
Package 2
Current
Management
Each comet shows change from Current Management
to Response Package 2 for one future
Slide 28
New Flow and Groundwater Targets
Decrease Urban and Agricultural
Reliability…
Response
Package 2
Response
Package 3
Each comet shows change from Response Package 2
to Response Package 3 for one future
Slide 29
…But improves environmental flows in
San Joaquin River and groundwater
levels in Tulare Lake
Increased
groundwater
Response
Package 3
Increased
environmental
flows
Response
Package 2
Each comet shows change from Response Package 2
to Response Package 3 for one future
Slide 30
More efficiency compensates for effects
of increasing flows and groundwater
levels
Response
Package 5
Response
Package 3
Each comet shows change from Response Package 3
to Response Package 5 for one future
See Figure 5-17, Vol. 1
Slide 31
In summary: response packages reduce
vulnerabilities in San Joaquin and Tulare Lake
hydrologic regions
San Joaquin River Results
Tulare Lake Results
See Figures 5-19 & 5-21, Vol. 1
Slide 32
Key limitations of analysis
Uncertainties
o Land use scenarios may not be expansive enough
o Other uncertainties may be important
Performance metrics
o Other decision criteria not yet represented
Management strategies
o Small number of response packages
o No Delta strategies
o No surface storage strategies
High level planning model
o Does not capture some detailed operations and contracts
o Does not include sea level rise
o Coarse cost estimates
Slide 33
www.rand.org/jie/centers/water-climate-resilience.html