Sediment Yield and Reservoir Sedimentation in Highly Dynamic Watersheds: The Case of Koga Reservoir, Ethiopia

Soil erosion is exacerbated by unsustainable land-use activities and poor management practices, undermining reservoir storage capacity. To this effect, appropriate estimation of sediment would help to adopt sustainable best practices that lead efficient operations. This paper aims investigate the spatial variability yield, amount delivery into reservoir, sedimentation in Koga Reservoir using Water Assessment Tool (SWAT). Sediment yield entered were also estimated a rating curve, providing an alternative approach spatially referenced SWAT generated suspended load. was calibrated from 1991 2000 validated 2002 2007 monthly observations. Model performance indicators showed acceptable values Nash-Sutcliffe efficiency (NSE) correlation coefficient (R2), percent bias (PBIAS) for flow (NSE = 0.75, R2 0.78, PBIAS 11.83%). There good agreement between measured simulated yields, with NSE, R2, validation 0.80, 0.79, 6.4%, respectively. The curve predictions comparable mean annual 62,610.08 ton/yr 58,012.87 ton/yr, study provides implication extent interventions required meet load targets receiving better understanding catchment processes responses anthropogenic natural stressors mixed land use temperate climate catchments. Findings benefit policymakers towards water decisions serve as prototype other catchments where may be implemented. Specifically, validating first step support policymakers, who are faced implementing decisions.