WATER DEMAND ASSESSMENT AND ALLOCATION: CASE STUDY BARO WATERSHED

Abstract

Watershed is considered to be the ideal unit for management of the natural resources. Extraction of watershed parameters using (GIS) and use of mathematical models is the current trend for hydrologic evaluation of watersheds. The aim of this thesis is to estimate water demands of future water resource development projects on the Baro watershed using SWAT models to assess water availability and WEAP models to assess the water demand of the study area. The SWAT model was calibrated and validated for measured stream flow at Baro near Gambela gauging stations. The calibration and validation result showed that model performance evaluation statistics (coefficient of determination (R 2 ) and Nash-Sutcliffe model efficiency (ENS)) were in the acceptable range (R 2 =0.76 ,E NS =0.72 for calibration and R 2 =0.7,E NS=0.63 for validation). This indicates that the observed values show good agreement with simulated flow value. In this study the watershed yields average annual surface runoff of 477.07 mm. Using WEAP, this study investigated the trend of supply and demand in Baro catchment . The assessment model is computed based on two scenarios, Scenario1: Irrigation project development and Scenario 2: changing crop patterns, in order to see how Baro watershed responds to the supply of water resources. Based on the result, there will be unmet demand in both scenarios The study area tends to experience more water scarce problem in the second scenario; ―changing crop patterns since the crops are consuming much water.