Sediment Yield Estimation and Effect of Management Options on Sediment Yield of Kesem Dam Watershed, Awash Basin, Ethiopia

Assessing sediment yield and identifying hotspot areas play a significant role for watershed management. Watershed models can be used for such processes. Therefore, this study aims to develop watershed model and estimate sediment yield, including mapping the spatial distribution of sediment yield for the Kesem Dam watershed (Ethiopia), which had experienced intensive agricultural activities and high sediment loadings problems. The study also aims to evaluate the effect of implementing management options on sediment reduction especially in high sediment yielding areas. The most widely used Soil and Water Assessment Tool (SWAT) model was used for sediment yield modeling and management options implementation. We developed the SWAT model of the Kesem Dam watershed for the period 1994-2010 based on available geo-spatial and hydro-meteorological data of the watershed. Using observed streamflow and sediment yield data of the watershed, the model was calibrated for the period 2000-2006 and validated for the period 2007-2010. Parameters used for the model calibration were identified based on sensitivity analysis. The performance of the model was evaluated by coefficient of determinations (R-2), Nash-Sutcliffe efficiency (NSE), and percent bias (PBIAS). SWAT adequately reproduced the observed daily flows and sediment loads temporal evolution with R-2 and NSE >= 0.7 and PBIAS < 15% both for the calibration and validation periods. The mean annual sediment yield of the watershed was 11.43 t/ha/yr. The model also identified areas with the highest sediment yields of 24 to 29 ton/ha/yr, indicating the suitability of the model to implement and assess the impacts of management options. However, treating those areas with different sediment management options reduced the annual average sediment yield by 80% under vegetative filter strips. These findings can be used as inputs for reducing sediment loadings to the Kesem dam watershed and implementing sustainable watershed management of the watershed and other similar areas. (C) 2020 African Institute of Mathematical Sciences / Next Einstein Initiative. Published by Elsevier B.V.