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Regional Knowledge Exchange on Decision-support Tools and Models to Project Improved

Strategies for Integrated Management of Land, Water and Livelihoods

WEAPWater Evaluation and Planning System

Vinay Nangia, Ph.D.

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2

How much river water can a user use?

River flow ≠ Water available to a user

Also reach gains/losses, reservoir storage, consumptive use, return flows, groundwater, soil moisture

Delivery targets and water allocation prioritiesAppropriation doctrine (first in time, first in right)By purpose (e.g.: urban demands before

environmental)By location (e.g.: upstream, then downstream, or

reverse)

Prior withdrawals and deliveries

Changes from month to month and year to year

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How much river water can a user use?

It’s complicated to track

We’d like a model to do this

WEAP HistoryFirst developed in 1992WEAP21 version in 2005Already 119 published applications (30 in 2012)

Key model development steps

1. Draw the system schematic

2. Identify data for system components

3. Enter data and run the model

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WEAP HighlightsIntegrated water resources planning systemGIS-based, graphical drag & drop interfaceBasic methodology: physical simulation of water demands and suppliesAdditional simulation modeling: user-created variables and modeling equationsScenario management capabilitiesLinks to spreadsheets & other models

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Modeling process in WEAPDefining the study area

and time steps for analysis

Creating of the current account

Creating of future scenarios

Evaluation of results

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WEAP system elementsDemand sites: A set of users sharing physical distribution system (geographical)

Catchments: Points created to account for precipitation, ET, runoff, irrigation and yield from agricultural and non-agricultural fields

Reservoirs: Reservoir sites on the river

Stream flow gauges: Points where actual flow measurements are acquired, can be compared with simulated values

Groundwater nodes: Represents groundwater sources and aquifers

Waste water treatment plants

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WEAP Capabilities

Can do Cannot doHigh level planning and strategic analysis at local, national and regional scales

Demand management

Water allocation

Daily operations

Least-cost optimization of supply and demand

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Examples of analysesSectoral demand analysesWater conservationWater rights and allocation prioritiesGroundwater and streamflow simulationsReservoir operationsHydropower generationPollution trackingEcosystem requirements

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WEAP for vulnerability…Alternative baseline scenarios can examine vulnerability of water supplies to different demographic, technological, and climatalogical/hydrological futures

and adaptability…Alternative policy scenarios can explore demand and supply management options for adapting to future vulnerabilityImplications for the multiple and competing demands on water systemsImplications of policies can be evaluated (ability to meet water needs, hydropower availability, pollution loadings, costs, etc.)

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Sectoral water demands

Irrigation

Livestock

Mining

Industrial

Commercial

Ecosystems

Domestic

Major Cities

Total Water Demand

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Illustrative Demand Structure

Agriculture

Industry

Municipal

CottonRiceWheat...

Electric PowerPetroleumPaper...

South CityWest City...

Irrigation...

CoolingProcessingOthers

Single FamilyMulti-family...

FurrowSprinklerDrip

StandardEfficient...

KitchenBathingWasherToilet...

SECTOR SUB-SECTOR END-USE DEVICE

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Demand methods in WEAPRainfall-runoff catchment method

Mass balance “2 bucket” method

Root zone soil moisture and below

Physically-based (soil, plant, climate, irrigation)

Computes crop ET, surface runoff, subsurface lateral seepage, deep percolation to GW, applied irrigation water

Suitable for climate change scenarios

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Demand methods in WEAPPer capita “unit” water use method

Unit rate: Unit water use rate (e.g.: L/person, L/ha, L/home)

Total activity level: Total level of activity for the demand category (people, area, homes)

Demand volume = Unit rate X Total activity level

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Ag demand (Physical parameters)

SoilSoil moisture holding capacityHydraulic conductivityInitial soil moisture

PlantCrop coefficient (Kc)

LAI (crop canopy to control surface runoff)

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Ag demand (Physical parameters)

ClimatePrecipitationTemperatureRHWind speedLatitudeMelting point temp (snowmelt runoff)Freezing point temp (snowpack accumulation)

IrrigationLower soil moisture threshold (to start irrigation)Upper soil moisture threshold (to stop irrigation)

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Urban demandUrban indoor (per capita)Single familyMulti familyCommercialIndustrial

Urban outdoor (catchment)Single familyMulti familyCommercialLarge landscape

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SuppliesRiversGroundwater storage capacitymaximum monthly withdrawalnatural recharge

Diversions (e.g. canals, pipelines)Reservoirs Other (e.g. desalination)

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Schematic View

Click and drag to create a

new demand site

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Network

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Data ViewData is displayed numerically and

graphically

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Results ViewResults can be

displayed in wide range of formats

and scales

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AvailabilityEvaluation version available at no charge (CDs available here) or download from http://www.weap21.org

Full version requires license, available from SEI

Training is needed for majority of usersSystem requirements

Windows 95 or later

32 MB of RAM (64 MB suggested)

Imports from/exports to Excel and Word (not required)

Uses standard ArcView GIS shape files. ArcView is not required.

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Thank you