Stream flow modeling of upper Awash River basin using Soil and Water Assessment Tool.

Abstract

Stream flow is the main hydrological factor which influences the hydrological characteristics in many ways and shows their importance in balanced agricultural watersheds. Stream flow reflects the amount of water moving off the watershed and into the channel and the amount being removed from the stream. Geographic Information System version based Soil and Water Assessment Tool has been used to evaluate sensitivities and simulate patterns of stream flow in the Upper Awash River basin located in Oromia, Ethiopia.  The data used in the study were Digital Elevation Model, LULC map, soil characteristics map, and hydro-meteorological variables that were collected from different sources. The model was run for 24 years (1991-2014) of metrological and spatial data to simulate stream flow. Sensitivity analysis was done to assess parameters governing the model output. Model calibration and uncertainty analysis were performed with sequential uncertainty fitting that is linked with SWAT-CUP program. The coefficient of determination (R²) and Nash-Sutcliffe efficiency (NSE) were used to evaluate model efficiency. The model was calibrated for eight years (2001 to 2008) and validated for six years (2009 to 2014). The results found for flow R² =0.69, NSE = 0.69 during calibration and R² = 0.88, NSE =0.74 during validation.