WEAP is a software tool for integrated water resources planning that attempts to assist rather than substitute for the skilled planner. It provides a comprehensive, flexible and user-friendly framework for planning and policy analysis. A growing number of water professionals are finding WEAP to be a useful addition to their toolbox of models, databases, spreadsheets and other software.
WEAP operates on the basic principle of a water balance and can be applied to municipal and agricultural systems, a single watershed or complex transboundary river basin systems. Moreover, WEAP can simulate a broad range of natural and engineered components of these systems, including rainfall runoff, baseflow, and groundwater recharge from precipitation; sectoral demand analyses; water conservation; water rights and allocation priorities, reservoir operations; hydropower generation; pollution tracking and water quality; vulnerability assessments; and ecosystem requirements. A financial analysis module also allows the user to investigate cost-benefit comparisons for projects.
The analyst represents the system in terms of its various supply sources (e.g., rivers, creeks, groundwater, reservoirs, and desalination plants); withdrawal, transmission and wastewater treatment facilities; water demands; pollution generation; and ecosystem requirements. The data structure and level of detail can be easily customized to meet the requirements and data availability for a particular system and analysis.
WEAP applications generally include several steps.
- Study definition: The time frame, spatial boundaries, system components, and configuration of the problem are established.
- Current accounts: A snapshot of actual water demand, pollution loads, resources and supplies for the system are developed. This can be viewed as a calibration step in the development of an application.
- Scenarios: A set of alternative assumptions about future impacts of policies, costs, and climate, for example, on water demand, supply, hydrology, and pollution can be explored. (Possible scenario opportunities are presented in the next section.)
- Evaluation: The scenarios are evaluated with regard to water sufficiency, costs and benefits, compatibility with environmental targets, and sensitivity to uncertainty in key variables.
WEAP is developed by the Stockholm Environment Institute's U.S. Center.
New Features in Version 2018.0
- Automatic Catchment Delineation: WEAP can delineate catchments and rivers (using digital elevation data), calculate land area (disaggregated by elevation band and land cover), and download historical climate data for each catchment (by elevation band). This will greatly simply the process of setting up and modeling catchment hydrology. WEAP will automatically download global datasets for elevation, land cover and climate as needed. WebHelp/index.html#Catchment_Delineation.htm
- Tags: Tags allow you to create entirely new structures for organizing the data and objects in your model, and can be used for grouping, organizing, filtering, highlighting and subtotaling results. Every object on the schematic can be assigned one or more user-defined tags, and tags can be grouped into user-defined tag categories. Think of tag categories as different dimensions for your data, such as location (north, south, east, west), river basin, economic sector (industry, agriculture) or ownership (state, federal). WebHelp/index.html#ManageTags.htm
- Plugins: Plugins can be added to your models to extend their capabilities, such as calculating reservoir evaporation, agricultural residues or energy requirements. Create your own plugins or download them from the WEAP website or from colleagues. WebHelp/index.html#Plugins.htm
- Access to commercial LP solvers (Gurobi and XA) to greatly accelerate calculations on very large models -- up to ten times faster. WebHelp/index.html#LPFormulation.htm
- Filtering the Schematic and Tree: You can selectively show or hide objects on the Schematic and Data View Tree based on their scenario, type and tags. For example, to show only objects that are not active in Current Accounts, set the filter to: Scenario <> Current Accounts. WebHelp/index.html#FilteringSchematic.htm
- Link to MODFLOW 2005 and MODFLOW NWT groundwater models WebHelp/index.html#Linking_to_MODFLOW_Full.htm
- Numerous other improvements, optimizations and bug fixes.