WEAP (the Water Evaluation and Adaptation Planning system) is a model-building tool for water resource planning and policy analysis[1] that is distributed at no charge to non-profit, academic, and governmental organizations in developing countries.
WEAP is used to create simulations of water demand, supply, runoff, evapotranspiration, water allocation, infiltration, crop irrigation requirements, instream flow requirements, ecosystem services, groundwater and surface storage, reservoir operations, pollution generation, treatment, discharge, and instream water quality. The simulations can be created under scenarios of varying policy, hydrology, climate, land use, technology, and socio-economic factors.[2] WEAP links to the USGS MODFLOW groundwater flow model and the US EPA QUAL2K surface water quality model.
Establishing the ‘current accounts’ and building scenarios and evaluating the scenarios about criteria are the main WEAP applications in Simulation problems.[3]