international center for agricultural research in the dry areas regional knowledge exchange on...
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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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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 1992
WEAP21 version in 2005
Already 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 Highlights
Integrated 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 WEAP
Defining 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 elements
Demand 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 do
High 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 analyses
Sectoral 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 vulnerability
Implications for the multiple and competing demands on water systems
Implications 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 WEAP
Rainfall-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 WEAP
Per capita “unit” water use methodUnit 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 capacity
Hydraulic conductivity
Initial soil moisture
Plant
Crop coefficient (Kc)
LAI (crop canopy to control surface runoff)
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Ag demand (Physical parameters)
ClimatePrecipitation
Temperature
RH
Wind speed
Latitude
Melting 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 demand
Urban indoor (per capita)Single family
Multi family
Commercial
Industrial
Urban outdoor (catchment)Single family
Multi family
Commercial
Large landscape
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Supplies
RiversGroundwater 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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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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Availability
Evaluation 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.