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. The stream flow and
sediment yield of soke watershed was quantified