SWAT-WEAP Model-based Water Supply-Demand Analyses and Identification of Critical Areas under Different Scenarios in Bilate River Watershed, Ethiopia

Water Resources Engineering and Management

Abstract

Water scarcity has increased the interest in improving water use efficiency and productivity in various parts of the world. As a solution to the problems associated to water scarcity, it is very useful to conduct water demand-supply and water allocation analyses (under current and future condition), even after water shortage has manifested itself, as it would lead to seeking a win-win situation among different water users (demand sites) in the watershed. Accordingly, this study focused on water allocation for existing and future demands in Bilate River Watershed using the WEAP model as by generating stream flow data using the SWAT model. For this purpose, observed meteorological and hydrological data for the period of 2010–2019 were employed. The model outputs were further analyzed to determine long-term mean flow values. Under the Current Scenario, the irrigation, domestic and livestock water demands were found to be 49.05 MMC, 21.41MMC and 8.58 MMC, respectively, with a total of 79.04 MMC. Under this scenario, the available water was not found to meet the demands in the months from October to February, particularly at Badessa and Chorake sub-watersheds. Under the reference scenario, the annual unmet water demand in the watershed as a whole changes from 1.21 MMC in 2021 (current scenario) to 1.78 MMC in 2030, which is expected to increase to 5.78 MMC in 2030 under the Increased water demand scenario with irrigation expansion, population growth, and environmental flow consideration. Thus, to address the current and eve future supply-demand gap, a storage structure needs to be constructed at appropriate place.