Application of Water Evaluation and Planning (WEAP) tool for Water Resource Management
Francis 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 all life depends.
Even though water constitutes three quarters of the earth surface, not all this is available for human consumption.
There is a great difference in availability of water from region to region, with extreme cases in deserts
Scarcity in the amount of water calls for efficient water resource management.
Water resource management Aims at optimizing the available
natural water flows to satisfy competing needs while ensuring that quality is not compromised.
Key principles of Water Resource Management Water and sanitation sector is affected by
water use in other sectors There are potential positive and negative
impacts of all water uses There is need for a holistic view to ensure
equitable and efficient water use
Water Evaluation and Planning (WEAP)
Is a microcomputer tool for water resource planning
Implements an integrated approach, placing supply
projects in the context of demand-side issues,
quality and ecosystem preservation.
WEAP allows users to implement “what if”
analysis
WEAP tool is developed by Stockholm
Environmental Institute (USA)
Objectives
Create a simple water management system with
supply and demand nodes
Analyse optimal water use within the water
management system as a result of changing
demand and supply scenarios
Analyse the impact of population growth and
climate change on demand and supply
equilibrium
Area of Study/Demonstration Site
Weap River Basin
This is a hypothetical data set associated
with WEAP system.
Designed to aide the user in exploring
various components of WEAP
Modeling Process in WEAP
Defining the study area and time steps for analysis
Evaluation of results
Creation of future scenarios
Creation of the current Accounts
Schematic view: • consists of GIS tools that can be used to configure the
system• Icons for drainage components are used to drag and
drop components at the appropriate position
Notes:Documentation of data specifications and assumptions
Scenario Explorer:Allows the user to design and display unique outputs from various model aspects, gives a “bird’s eye” view of the model
Results view:• Allows for presentation of model outputs both in graphical and tabular format
Data view:• This is where the system data is modeled•Allows for assumptions to be made and can be dynamically linked to Excel
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
Ground water nodes: represent ground water sources and aquifers
Waste Water treatment plants
Creating system elements
• GIS layers (shapefiles and topographic maps) than can be used as geographic references for the various elements
Defining time steps
Creating Current Accounts
Key aspects to be defined include: Key assumptions in the system Demand sites in the system and the current
status of water demand Hydrology, defining the current inflows into
the system and the expected variations Supply and resources, supply nodes and
transmission links and the associated costs in running and maintaining
Water treatment plants and associated cost of treatment
Creating Current Accounts
Creating Scenarios in WEAP• The scenario explorer can be used to create new (rename) scenarios and to define the variables associated with them•Previously defined scenarios can also be deleted
Impact of population growth on water demand
In the study an assumption is made that
the population will grow uniformly at a
rate of 3.3% per annum, for the period
2010-2020
Expression builder within WEAP can be
used to calculate the interpolated
population of each year if the population
of the start year is known.
Impact of climate change on water resources
Two methods can be used to account for impact of climate change on the hydrology of the system ReadFromFile method: Used when detailed
forecasts are available and can simply be read into the system
Water Year Method: Each year is defined either as “normal”, “wet”, “very wet”, “dry”, “very dry”. The inflows of wet, very wet, dry and very dry years relative to a normal year can be defined. E.g if a wet year averagely has 25% more inflow than a normal year then a value of 1.25 will be set to the wet year relative to the normal year.
Impact of climate change on water resources
2010 2011
2012 2013
2014 2015 2016
2017 2018 2019 2020
Normal
wet very wet
wet normal
dry dry very dry
very dry
dry normal
Results
Unmet demands
Unmet demands
Ground Water Storage
Exporting the system to Google Earth
Conclusion
WEAP is a valuable tool for water resource planning and evaluation, easy to learn and use. Very useful for policy decision in water resource management.
It is possible to use GIS layers for referencing and visualization, the integration needs to be enhanced to allow for analysis and map creation
The tool has additional inbuilt modules like MODFLOW and MODPATH which should be explored