The Central Valley WEAP Model
Workshop 3: Analytical Tools for Evaluating Water Supply,
Hydrodynamic, and Hydropower Effects
Tuesday, November 13, 2012
David Purkey, Ph.D.
US Water Group Leader, Stockholm Environment Institute
Water Evaluation and Planning System
Generic, object-oriented,
programmable, integrated
water resources management
modeling platform
Why WEAP? • WEAP is modern modeling software.
• WEAP has a global user community.
• WEAP is continuously upgraded by software engineers.
• WEAP is free for California government.
• WEAP includes NO dependencies on historical time series.
• WEAP integrates issues of concern in a consistent analytical platform.
• WEAP has been constructed for scenario analysis.
• WEAP is used for major system level planning exercises: – DWR State Water Plan Update;
– USBR Sacramento-San Joaquin Basin Study.
Pertinent WEAP Functionality
• Snow accumulation/melt
• Rainfall/runoff processes
• Evapotranspiration from both natural and cropped landscapes
• Soil moisture storage
• Groundwater dynamics, including stream aquifer interactions
• Hydraulic system operations, including hydropower
• Urban water demand
• Water allocation priorities, including environmental flows
• Surface water quality
• Financial accounting of costs and benefits.
N.B.: from comment letter submitted by SEI
Central Valley WEAP
Central Valley WEAP Model
Evolution
• Sacramento Valley
• EPA funded: finished in 2005
• Westside San Joaquin Valley
• CEC funded: finished in 2006
• Entire San Joaquin Valley
• DWR funded: finished in 2009
• Tulare Lake Basin
• USBR funded: finished in 2011
Upper Watersheds
25 “Rim” watersheds
delineated by land use
and elevation
Central Valley
21 Central Valley PA’s
divided by water use:
• Irrigated Agriculture
• Urban Indoor
• Urban Outdoor
• Managed Wetlands
Also includes:
• 22 in-stream flow
requirements
• 21 groundwater basins
• Inter-Basin transfers to
San Francisco, Central
Coast, and South Coast
21 Central Valley PA’s
divided by water use:
• Irrigated Agriculture
• Urban Indoor
• Urban Outdoor
• Managed Wetlands
Also includes:
• 22 in-stream flow
requirements
• 21 groundwater basins
• Inter-Basin transfers to
San Francisco, Central
Coast, and South Coast
Model Calibration
Calibrated to:
• Monthly inflows to major reservoirs (1970 – 2005)
• Agricultural, urban (indoor and outdoor), and managed
wetland water use (1998-2005)
• Reservoir storage (1990-2005)
• Groundwater use and groundwater elevations (1970-2005)
• Delta inflows, outflows and exports (1990-2005)
Model Calibration: Water Use
OBS WEAP OBS WEAP OBS WEAP
501 5 5 5 7 6 7 502 0 1 0 1 0 1 503 15 15 16 19 19 20 504 23 25 35 38 34 37 505 3 3 4 4 5 4 506 4 4 5 5 5 5 507 31 33 32 42 34 42 508 48 45 46 61 49 62 509 27 27 33 34 31 32 510 19 20 19 24 21 24 511 160 167 207 206 215 200
Total Sacramento River
HR 336 345 403 440 417 434
OBS WEAP OBS WEAP OBS WEAP
601 12 12 14 15 15 15 602 23 23 25 29 30 28 603 44 44 49 56 53 55 604 20 19 20 26 21 25 605 - 0 - 1 - 1 606 10 10 10 14 10 13 607 60 59 64 70 68 70
608 30 31 33 38 34 35 609 38 38 41 46 41 44 610 7 6 8 6 8 6
Total San Joaquin River
HR 244 243 264 300 279 291
Planning Area
1998 (Wet) 2000 (Normal) 2001 (Dry)
Planning Area
1998 (Wet) 2000 (Normal) 2001 (Dry)
050
100150200250300350400450500
OBS WEAP OBS WEAP OBS WEAP
1998 (Wet) 2000 (Normal) 2001 (Dry)
Ap
pli
ed
Wa
ter
(TA
F/ye
ar)
501 502 503 504 505 506 507 508 509 510 511
0
50
100
150
200
250
300
350
OBS WEAP OBS WEAP OBS WEAP
1998 (Wet) 2000 (Normal) 2001 (Dry)
Ap
pli
ed
Wa
ter
(TA
F/ye
ar)
601 602 603 604 605 606 607 608 609 610
Outdoor Urban
Model Calibration: Reservoir Storage
Sacramento River HR
Model Calibration: Delta Outflow
0
10,000
20,000
30,000
40,000
50,000
60,000
1990 1992 1994 1996 1998 2000 2002 2004 A
nn
ua
l F
low
(T
AF
/ye
ar)
Net Delta Outflow
Simulated Observed
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Mo
nth
ly F
low
(T
AF
/mo
nth
)
Net Delta Outflow
Simulated Observed
Model Calibration: Groundwater Elevation
Scenarios Analysis Framework
Outcome Metrics: • Delivery reliability
• Unmet demands
• Groundwater & surface water storage
Uncertainties: • Demographic
• Land Use / Land Cover
• Climate Change
Response Strategies: • Add infrastructure
• Improvements in system efficiency
• Wastewater reuse
• Demand Management
Grouped Strategies into Response Packages
for Analysis
Strategies Baseline
(#1) #2 #3 #4 #5 #6 #7
Urban Water
Use
Efficiency o (current) + + ++ ++ ++ +++
Agricultural
Water Use
Efficiency o o o + + + +++
Groundwater
Recharge o o + o + +++ +++ Recycled
Water Use o + ++ + ++ +++ +++
Response Packages
15
Vulnerabilities Are Reduced With
Response Packages
Scope Analysis
Evaluate Strategies
Over Many Scenarios
Characterize
Vulnerabilities
Summarize Tradeoffs
Among Strategies
“Robust, Adaptive Strategies”
And Key Tradeoffs
Augment
Strategies
Base Case
Moderate
Increases
Some Other California WEAP
Applications
• Santa Clara Valley (utility planning)
• South Fork American River (utility planning)
• San Gregorio Creek (State Board hearings)
• East Bay Area (utility planning)
• Western Sierra Nevada (research)
• Cosumnes, American, Bear, and Yuba Basins (IRWMP)
• Inland Empire (urban water management plan)
• Butte Creek (research)
• Cache Creek (research)
Why WEAP? • WEAP is modern modeling software,
– not site specific code.
• WEAP has a global user community, – not a small number of proficient users.
• WEAP is continuously upgraded by software engineers, – not a static code managed by water engineers.
• WEAP is free for California government, – no need for expensive solvers.
• WEAP includes NO dependencies on historical time series, – Not restricted to period of record hydrology.
• WEAP integrates issues of concern in a consistent analytical platform. – Not an assemblage of otherwise disconnected models.
• WEAP has been constructed for scenario analysis. – Does not require extensive coding to represent new management arrangements.
• WEAP is used for major system level planning exercises: – DWR State Water Plan Update;
– USBR Sacramento-San Joaquin Basin Study.
Thank You
www.weap21.org
www.sei-international.org