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Create expert water models more easily with new version of WEAP

A major update to SEI’s flagship water modelling tool enables policy-makers and researchers to more easily determine watershed boundaries and river pathways, marking a big step forward for science-based water management.

Emily Yehle / Published on 8 May 2018

The Water Evaluation and Planning System – known as WEAP – now includes advanced GIS functionality to offer users a simple way to build catchment models, or models of where and how the natural landscape collects water. WEAP now automatically downloads global datasets for elevation, land cover and climate; users need only to point and click to access land area calculations and see catchment boundaries and river networks.

“Building catchment models has always been the most challenging part of watershed modelling, requiring GIS expertise and access to and processing of databases,” said SEI-US Deputy Director and WEAP developer Jack Sieber. “This new version of WEAP should really jump start that process, allowing users with less expertise to build models once reserved for experts.”

Such access and ease supports SEI’s goal to further sustainable water management by providing tools that promote holistic, transparent and robust decision-making.

WEAP is used around the world for policy-making, with more than 28,000 users in 180 countries. It is user-friendly and free to developing countries, making it the de facto standard for integrated water resource planning. It can be used at the watershed, state, national or regional scale.

Recent work includes helping Bolivia address a growing water crisis with the first-ever comprehensive model of the country’s rivers, lakes and streams. California state and local governments also use WEAP extensively to address ecosystem requirements.

In addition to improved catchment delineation, the new version of WEAP offers policy-makers and researchers a slew of improved features. They include the ability to:

  • Create tags to organize data and objects. Users can assign one or more tags to every object in their model, enabling them to group, organize and filter their results. Such tags, for example, could identify data by location, river basin, economic sector, or land ownership.
  • Create and add plugins, or download them from the WEAP website or from colleagues. Plugins can add to a model’s capabilities, such as enabling users to calculate reservoir evaporation or energy requirements.
  • Utilize commercial Linear Programming (LP) solvers (such as Gurobi and XA) to greatly accelerate calculations on very large models. This can make calculations up to ten times faster.
  • Filter a model’s schematic and tree. Users can thus selectively show or hide objects on the schematic and data view tree, based on scenario, type or tags.
  • Link to two popular open-source groundwater flow models from the U.S. Geological Survey, called MODFLOW 2005 and MODFLOW NWT.

The new version of WEAP also includes numerous other improvements, optimizations and bug fixes.

Together, these improvements will make WEAP even more accessible and informative to policy-makers and stakeholders, who use the platform to see current conditions, explore future scenarios, and identify policy options for balancing environmental and development goals amid climate uncertainty.

“WEAP is unique in the power, flexibility and ease of use it offers,” Sieber said. “These improvements make it even more comprehensive in combining physical hydrology with management and policy options.”

Profile picture of Jack Sieber
Jack Sieber

Senior Scientist


Design and development by Soapbox.