ESTIMATION OF SEDIMENT YIELD USING SWAT MODEL: A CASE OF SOKE RIVER WATERSHED, ETHIOPIA

Soil erosion is a process of detachment/dispatch/ of soil particles due to rain drop and runoff. This results deposition of sediment causing reduced flood carrying capacity affects water qualify instability of structure and natural streambeds and banks. For accurate and easy estimation of runoff and sediment yield, it can be done by using physical based continuous hydrological model. Among the many hydrological model Soil and Water Assessment Tool (SWAT) is the more promising model for simulations in predominant agricultural watershed. Moreover, the model is better in assessing both spatial and temporal variability of the hydrological process under both small and very large watershed. This study is about the estimation of sediment yield and reduction of sediment yield with appropriate mitigation measures. The input data for the model were obtained from different organizations; After the input data are organized and assembled it was used for model simulation. Later simulation result was calibrated and validated using Calibration Uncertainty Procedure (SWAT-CUP). The efficiency evaluation criteria’s Coefficient of determination (R2), and the Nash-Sutcliffe simulation efficiency (ENS) were used for performance evaluation of the model. The result from the calibration and validation of both flow and sediment were greater than 0.7; this indicated that there was very good agreement between observed and simulated outputs