Application of Water Evaluationand Planning (WEAP) tool forWater Resource ManagementFrancis Oloo & Jigme Thinley
Outline Introduction Objectives Modeling process in WEAP Creating Scenarios in WEAP Impact of population growth Impact of climate change Results Conclusion
Introduction Water is an essential resource upon which alllife depends. Even though water constitutes three quartersof the earth surface, not all this is available forhuman consumption. There is a great difference in availability ofwater from region to region, with extremecases in deserts Scarcity in the amount of water calls forefficient water resource management.
Water resource management Aims at optimizing the available naturalwater flows to satisfy competing needswhile ensuring that quality is notcompromised. Key principles of Water ResourceManagement Water and sanitation sector is affected by wateruse in other sectors There are potential positive and negative impactsof all water uses There is need for a holistic view to ensure
Water Evaluation and Planning(WEAP) Is a microcomputer tool for water resourceplanning Implements an integrated approach, placingsupply projects in the context of demand-sideissues, quality and ecosystem preservation. WEAP allows users to implement “what if”analysis WEAP tool is developed by Stockholm
Objectives Create a simple water management system withsupply and demand nodes Analyse optimal water use within the watermanagement system as a result of changingdemand and supply scenarios Analyse the impact of population growth andclimate change on demand and supply equilibrium
Area of Study/DemonstrationSite Weap River Basin This is a hypothetical data set associated withWEAP system. Designed to aide the user in exploring variouscomponents of WEAP
Modeling Process in WEAPDefining the study area andtime steps for analysisEvaluation of resultsCreation of future scenariosCreation of the currentAccounts
Schematic view:• consists of GIS tools that can be used to configure thesystem• Icons for drainage components are used to drag and dropcomponents at the appropriate positionNotes:Documentation of data specifications and assumptionsScenario Explorer:Allows the user to design and display unique outputs from variousmodel aspects, gives a “bird’s eye” view of the modelResults view:• Allows for presentation of model outputs both in graphical andtabular formatData view:• This is where the system data is modeled•Allows for assumptions to be made and can be dynamically linkedto Excel
WEAP System Elements Demand sites: A set of users sharing physicaldistribution system (geographical) Catchments: Points created to account forprecipitation, ET, runoff, irrigation and yield fromagricultural and non-agricultural fields Reservoirs: Reservoir sites on the river Stream flow gauges: points where actual flowmeasurements are acquired, can be comparedwith simulated values Ground water nodes: represent ground watersources and aquifers Waste Water treatment plants
Creating system elements• GIS layers (shapefiles and topographic maps) than can be used asgeographic references for the various elements
Key aspects to be defined include: Key assumptions in the system Demand sites in the system and the currentstatus of water demand Hydrology, defining the current inflows into thesystem and the expected variations Supply and resources, supply nodes andtransmission links and the associated costs inrunning and maintaining Water treatment plants and associated cost oftreatmentCreating Current Accounts
Creating Scenarios in WEAP• The scenario explorer can be used to createnew (rename) scenarios and to define thevariables associated with them•Previously defined scenarios can also bedeleted
Impact of population growth onwater demand In the study an assumption is made that thepopulation will grow uniformly at a rate of 3.3%per annum, for the period 2010-2020 Expression builder within WEAP can be usedto calculate the interpolated population of eachyear if the population of the start year isknown.
Impact of climate change on waterresources Two methods can be used to account forimpact of climate change on the hydrology ofthe system ReadFromFile method: Used when detailedforecasts are available and can simply be readinto the system Water Year Method: Each year is defined eitheras “normal”, “wet”, “very wet”, “dry”, “very dry”.The inflows of wet, very wet, dry and very dryyears relative to a normal year can be defined.E.g if a wet year averagely has 25% more inflowthan a normal year then a value of 1.25 will be setto the wet year relative to the normal year.
Impact of climate change on waterresources2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020Normalwet verywetwet normal dry dry verydryverydrydry normal
Conclusion WEAP is a valuable tool for water resourceplanning and evaluation, easy to learn anduse. Very useful for policy decision in waterresource management. It is possible to use GIS layers for referencingand visualization, the integration needs to beenhanced to allow for analysis and mapcreation The tool has additional inbuilt modules likeMODFLOW and MODPATH which should beexplored