A Study on the Applicability of a Swat Model in Predicting the Water Yield and Water Balance of the Upper Ouémé Catchment in the Republic of Benin

This study investigates the applicability of a Soil and Water Assessment Tool (SWAT) model in predictions of the water yields and water balance of the Upper Oueme catchment in the northern part of the Republic of Benin. Meteorological and hydrological data for a period of 20 years were collected from the Meteorological Agency of Benin and the National Directorate of Water respectively. Spatial data such as a Digital Elevation Model and land use and soil maps were also extracted from suitable databases. Geographic information system (GIS) software was applied in combination with SWAT to process the spatial data and simulate the streamflow record. A good correlation between the simulated and observed data during the calibration and validation was found, using statistical measures such as the Nash-Sutcliffe Efficiency (NSE>0.65%), the standard deviation ratio (RSR<0.6), percent bias (±10%≤PBIAS<±15%), and the coefficient of determination (R²=0.78). An estimated potential water yield of 18,671.61mm in the catchment over the period of the simulation suggests that subsistence agriculture is sustainable in the area. The model is suitable for estimating the water yield and water balance in the catchment.