Module: WEAP

Submitted by Michael Rastall 28th January 2013 16:56
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The short video above provides a brief introduction to WEAP's Scenario Explorer which can be thought of as a dashboard with controls and gauges, where you can change key model inputs and instantly see how those changes affect the results.

Background to the method

The Water Evaluation and Planning system (WEAP) is a computer software tool used for analyzing water resources systems. It has a graphically based user interface which facilitates the entry of data and analysis of results. At its core WEAP calculates a water balance between supplies and demands. This allows users to determine when and where shortages in a water resources system may occur.

What are the ideal situations in which it is applied?

While WEAP can be applied to a wide rage of problems across a range of spatial and temporal scales, it typically requires that users characterize the supply of water, the characteristics of the conveyance and storage of water, and the demands for water. Users can choose from several methods for characterizing supplies and demands depending on the level of detail required and the availability of data.

Ideally, it can be used in the context of water conveyance restrictions such as pipeline and reservoir capacities. It also has a robust scenario capability that allows users to quickly and easily design and test future responses to water supply shortages.

Strengths and Weaknesses

The strengths of WEAP are its well designed interface, ease of scenario creation, documentation and training modules. This makes it possible for novice users to quickly become adept at using the software. As with all models of this type, an accurate representation of a water resources system often requires extensive data. These data are increasingly available through on-line sources, however, their use does require familiarity with water resources planning and data manipulation.

5 things you should know about WEAP once you have gone through these learning resources:

You should be aware of how:

  1. Water supplies can be represented in WEAP.
  2. Demands can be represented in WEAP.
  3. To create scenarios in WEAP.
  4. To characterize water conveyance and storage infrastructure in WEAP.
  5. To analyze results from the model.  

Click to animate

Applying the method - step-by-step

This module requires that a student learns how to use the WEAP tool to a basic level, and this includes installing the WEAP software and carring out a hands-on exercise, with example datasets and with guidance provided. Our starting point is the "WEAP in One Hour" tutorial on the Tutorial page. The step-by-step outline from the "WEAP in One Hour" tutorial is as follows:

  1. Creating a Study Area
  2. Setting General Parameters
  3. Entering Elements into the Schematic
  4. Getting First Results

The reference documentation for WEAP is the web-based User Guide or pdf which can be downloaded from the WEAP website

Examples of applying the method

This tool has been applied worldwide by practitioners in water resources engineering, hydrology, agricultural hydrology, planning, etc. It has been featured in peer reviewed publications. For a more complete explanation and listing of applications please visit and see applications.

Some WEAP examples used in adaptation research/adaptation planning on weADAPT are:

Added value of the method for the field of climate adaptation

This tool can be used to study future scenarios of climate through the use of the built-in hydrology modules. This allows users to enter climate data derived from global climate models which in turn are used to calculate the timing and magnitude of supply and climate affected demand. The tool can then be used to compare future projections of demand with the projected supplies. Scenarios can be created in which different adaptation strategies are implemented and their impact on the balance of supply and demand can be estimated.

Contact details

Email Chris Young:

Further Resources