Estimation of Runoff and Sediment Yield Using Soil and Water Assessment Tool Model in Dedeba Watershed, Rift Valley Lake Basin of Ethiopia

Abstract

Runoff and sediment yield estimation is important in the watershed to alleviate soil erosion and identify hotspot area for intervention strategies. The  objectives of this study is to estimate runoff and sediment yield in sub watershed and prioritize and map the watershed in terms of sediment yield rate and runoff potential using SWAT model. From the result of the Global sensitivity analysis, fourteen highly sensitive parameters identified and used for calibration and validation. The model was calibrated manually by adjusting sensitive parameters using observed data from 1990 to 2001, and validation was done using observed data from 2002 to 2007. The model performance was checked by statistical model performance evaluators such as the coefficient of determination (R²) and Nash–Sutclife model efficiency (ENS) and it shows that the model has a high potential in the estimation of runoff and sediment yield. Statistical model performance evaluator of calibration result shows a satisfactory agreement between the observed and simulated stream flow and sediment yield parameters. Whereas, statistical model performance evaluator of validation result shows a good agreement between the observed and simulated stream flow and sediment yield parameters. Among 29 sub-watersheds, nine sub watersheds were more vulnerable/hotspot area to soil loss and potentially prone to erosion risk. Based on the hydrological simulation integrated watershed management plan should be implemented for effective land and water resource development. Hence, the outputs of this study will be used by decision maker to plan and implement appropriate soil and water conservation strategies in the hot spots area.

Keyword: Calibration, Runoff, Sediment Yield, SWAT model, Watershed and Validation

DOI: 10.7176/CER/18-1-02

Publication date: February 28^th 2026