ESTIMATION OF SEDIMENT YIELD USING SWAT MODEL FOR KATAR WATERSHED

The main objective of this study is to estimate the sediment yield to Lake Ziway from Katar catchment. In this study A physial, semi-distributed and continuous time, Soil and Water Assessment Tool (SWAT 2012) model having an interface with ArcView GIS software was used to estimate sediment yield and identify spatial distribution of sediment yield in the water shade. Sensitivity analysis, model calibration and validation were also performed to assess the model performance using (SWAT-CUP) on Katar River at Abura gauging station.. Fifteen sensitive parameters to stream flow were identified, of which runoff curve number (CN2) and Threshold depth of water in the shallow aquifer (REVAPMN) factor and similarly for sediment analysis six sensitive parameters were selected out of these channel re-entrainment linear parameter (SPCON), channel cover factor (CH_COV2), and channel erodibility factor (CH_COV1) was the most sensitive parameters affecting the hydrology of the catchment. The model was calibrated from 1992-2002 and validated from 2004-2008 G.C. Flow calibration gives coefficient of determination (R2), Nash-Sutcliffe (ENS) and Percent bias (PBIAS), 0.8, 0.77 and -6.63 respectively and Validation gives R2, ENS and PBIAS,0.78,0.75 and 5.3 respectively. Sediment calibration gives R2, ENS and (PBIAS), 0.75, 0.73 and-10 respectively and validation test gives R2, ENS and PBIAS, 0.65, 0.64, and 3.3 respectively. The stream flow and sediment yield of Katar Watershed was quantified and also the most sediment yielding part of the basin was identified. The model prediction result showed that the annual sediment yield leaving the watershed was found to be 2.1ton/ha/Yr