1. Application of Water Evaluation
and Planning (WEAP) tool for
Water Resource Management
Francis Oloo & Jigme Thinley

2. Outline
 Introduction
 Objectives
 Modeling process in WEAP
 Creating Scenarios in WEAP
 Impact of population growth
 Impact of climate change
 Results
 Conclusion

3. 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.

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. Creating system elements
• GIS layers (shapefiles and topographic maps) than can be used as
geographic references for the various elements

12. Defining time steps

13. Creating Current Accounts

14.  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

15. 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

16. 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.

18. 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.

19. Impact of climate change on water
resources
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Norma
l
wet very
wet
wet normal dry dry very
dry
very
dry
dry normal

20. Results

21. Unmet demands

22. Unmet demands

23. Ground Water Storage

24. Exporting the system to Google
Earth

25. 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