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