Groundwater as a
Statewide Resource
Professor Richard E. Howitt
Agricultural & Resource Economics, UC Davis
Professor Jay R. Lund
Civil & Environmental Engineering, UC Davis
Real work done by
Dr. Marion W. Jenkins Andrew J. Draper
Matthew D. Davis
Kenneth W. Kirby
Kristen B. Ward
Brian J. Van Lienden
Brad D. Newlin
Pia M. Grimes
Jennifer L. Cordua
Siwa M. Msangi
A Study Funded by
 State
of California Resources Agency
 National
 US
Science Foundation
Environmental Protection Agency
Overview
1) Groundwater’s statewide importance
2) Some questions
3) Why Economics?
4) Economic values for water use
5) CALVIN statewide model
6) Some early groundwater results
7) Conclusions and ongoing work...
Is Groundwater Important?
of California’s off-stream
supplies in average years
 30-40%
 More
groundwater use in dry years
 Total
storage capacity = 850 MAF
Major Groundwater Areas
 Sacramento
 San
Valley
Joaquin Valley
 Tulare
Basin
 Salinas
 South
Valley
Coast
Major State Groundwater Issues
1. Managing Conjunctive Use
2. Groundwater Mining
3. Recharge and Surface Activities
Some Questions
Conjunctive Use?
1. Promising locations?
2. Local Control and Coordination?
3. Operating Coordination?
4. Statewide Coordination?
Groundwater Mining?
1. Balancing short and long-term benefits
and costs?
2. Economic use of mined water?
3. Effects of actions statewide on local
groundwater mining?
Recharge and Surface Activities?
1. Agricultural return flows?
2. Urban return flows?
3. Stream-aquifer interaction?
Why Economics?
“When the well’s dry,
we know the worth of water.”
Benjamin Franklin (1746),
Poor Richard’s Almanac.
Economic Values for Water
 Willingness
to pay
 Agricultural
 Urban
 Environmental
Agricultural Water Use Values
 Economic
 SWAP
 24
value of water to farmers
model
Regions
 Values
by month
Agricultural Production Model
- SWAP
 Based
on CVPM model
 Expanded
 Monthly
 More
to include entire state
water decisions
detailed production
decisions
Agricultural Inputs
 Available
acreage, water, technology
 Production
 Prices
function for each crop
and costs
 Observed
farm data
Agricultural Water Use Values
July
June
August
Benefits ($ 000)
70,000
60,000
50,000
March
40,000
May
3,000
30,000
April
October
February
January
2,000
20,000
1,000
10,000
September
October
0
0
50
100 150
0
200
5
250
300
Deliveries (taf)
10
350
15
400
Urban Demand Model
 Residential
demand curves to estimate
value of water use
 Lost
production survey to estimate value
of industrial water use
Urban Inputs
 2020
demands
• Industrial and residential
 Observed
residential demand curve
 Industrial
production lost
 1995
retail water prices
Urban Outputs
 Monthly
 20
values of water
Urban regions
Urban Cost of Shortage Curves
Shortage Penalty ($1,000,000)
50
Winter
40
Spring
30
Summer
20
10
0
20
30
40
Deliveries (taf)
50
CALVIN
An Economic-Engineering
Optimization Model for
California’s Water Supplies
What is CALVIN?
 Entire
inter-tied California water system
 Surface
and groundwater systems
 Prescribes
 Based
monthly system operation
on economic benefits
 Maximizes
economic objectives
Data Flow
Ag Inputs
Urban Inputs
SWAP Model
Input
Databases
CALVIN
Optimization
Results
Urban
Demand
Model
Optimization vs Simulation
 Optimization
- What’s best?
• What water operations and allocations give
the best performance?
 Simulation
- What if?
• What is performance given a set of water
operation and allocation rules?
Optimization Components
Objective
Decisions
Constraints
Maximize
economic
benefits
Reservoir
releases
Mass balance
Storages
Allocations
Physical
capacities
Environmental
flows
Policies
Optimization vs Simulation?
 Should
be used together
 Optimization
needs more simplification
 Provides
economic information not
available from simulation
 Promising
solutions for detailed study
CALVIN vs Other Models
 Other
models like DWRSIM,
PROSIM, and CVGSM are
simulation models
 CALVIN
model
is an optimization
CALVIN and Other Models
DWRSIM
Operation
rule-based
economic ben.
legal/contracts
Projects/regions
CVP & SWP
Tulare Basin
S. California
Outputs
deliveries
benefits
“best”operation
Data-driven

PROSIM/ CVGSM
SANJASM

CALVIN

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

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CALVIN’s Innovations
1) Groundwater and Surface Water
2) Statewide model
3) Optimization model
4) Economic perspective and values
5) Data - model management
6) New management options
Model Schematic
• Over 1,200 spatial elements
• 56 Surface reservoirs
• 38 Ground water reservoirs
• 47 Agricultural regions
• 20 Urban demand regions
• 600+ Conveyance Links
Schematic Transparencies Here
Model Inputs
• Agricultural water values
• Urban water values
• Hydrology: Surface & ground water
• Facility capacities
• Operating costs
• Environmental Flow Constraints
• Policy Constraints
Hydrology Inputs
• 1921 - 1993 historical period
• Monthly inflows
• Surface inflows from DWR and
USBR data
• Groundwater from CVGSM and
local studies
CALVIN Represents Groundwater
• 1921 - 1993 historical period
• 38 Groundwater reservoirs
• Pumping and recharge decisions
• Fixed interbasin flows, inflows, and
losses
• Calibrated to CVGSM and
local studies
CALVIN’s Engine
 Army
Corps of Engineers Hydrologic
Engineering Center Prescriptive
Reservoir Model (HEC-PRM)
A
data-driven network flow
programming model
CALVIN and Groundwater
 Some
very preliminary results
 Semi-calibrated
 Some
 Don’t
model run
ideas
trust these numbers.
Mojave Groundwater
6000
4000
3000
2000
1000
Oct. 1921 -Sep. 1993
Oct-91
Oct-81
Oct-71
Oct-61
Oct-51
Oct-41
Oct-31
0
Oct-21
Storage (KAF)
5000
Mojave Flows
60
Outflow
Urban Return Flow
50
Natural Recharge
Mojave Basin Inflow
40
30
20
10
Oct. 1925 -Sep. 1941
Oct-40
Oct-38
Oct-36
Oct-34
Oct-32
Oct-30
Oct-28
Oct-26
0
400
40
200
30
0
20
-200
Outflow
10
-400
Mojave Basin Pipeline
Capacity Value
Oct-39
Oct-37
Oct-35
Oct-33
Oct-31
Oct-29
-600
Oct-27
0
Value ($/AF)
50
Oct-25
Flow (KAF)
Mojave Flows
What does this show?
 Groundwater
can serve both seasonal
and drought demands.
 “Optimized”
groundwater doesn’t
necessarily drain basins.
 External
inflows and outflows have
economic value statewide.
MWD Area Groundwater
Storage
700
Storage Shadow
Value
500
1200
900
600
100
Oct-40
Oct-38
Oct-36
Oct-34
-300
Oct-32
0
Oct-30
-100
Oct-28
300
Oct-26
Storage (KAF)
300
Shadow Value ($/AF)
1500
120
Outflow
700
100
Inflow
600
Marginal Value of
Inflow
500
80
60
300
40
200
20
100
Oct-40
Oct-38
Oct-36
Oct-34
Oct-32
Oct-30
0
Oct-28
0
Oct-26
Flow (KAF)
400
Value ($/AF)
MWD Area Groundwater
1500
Storage
300
1200
Storage Shadow
Value
200
100
0
600
-100
300
-200
Oct-91
Oct-81
Oct-71
Oct-61
Oct-51
Oct-41
-300
Oct-31
0
Oct-21
Storage (KAF)
900
Shadow Value ($/AF)
Long-Term Storage
So what?
 Values
of storage capacity and reach.
 Aquifer
suited for drought storage.
 Groundwater
mining has some
economic value.
 Groundwater
coordinated with other
supplies and demands.
Conclusions
 Groundwater
is a statewide resource.
 Coordination
is important.
 Economics
and Markets can help us
better employ groundwater.
 Optimization
models can suggest
promising solutions.
Ongoing Efforts
 Running
 Policy
model to working model
and capacity alternatives
 Database
 Much
& tool development
left to do...
More Information ...
 Web
site:
cee.engr.ucdavis.edu/faculty/lund/CALVIN
 Workshop:
Friday, Sept. 24, 10am-3pm
UC Davis Campus, 1120 Bainer Hall