Prediction of sediment yield of the Inxu River catchment (South Africa)using the MUSLE

The proposed site for the construction of a new dam(Laleni Dam)on the Tsitsa River in the Eastern Cape,South Africa falls within a high soil erosion zone,which is expected to affect the lifespan of the dam.Estimating the sediment yield of the catchment is important from a management perspective,and thus we designed this study to assess the applicability of the Modified Universal Soil Loss Equation(MUSLE).The original MUSLE was applied to the Inxu River sub catchment,upstream of a proposed dam,over a summer rainfall period extending from October 2016 to April 2017.A modified version of the MUSLE,incorporating a storage module,was later applied over the same period.Model calibration of the MUSLE with and without a storage model was tested against 7 months of recorded daily suspended sediment discharge data.With a storage model,we achieved a percentage bias,coefficient of efficiency and R2 of 2%,0.83 and 0.83,respectively,while without storage the performance statistics were markedly lower.These results suggest that a calibrated MUSLE can provide estimates of sediment yield that are valuable for regional planning,and that the inclusion of a storage component further improves the MUSLE application.Given the complexity of sediment generation and transport processes,a relatively simple empirical MUSLE model is a useful tool for initial sediment yield estimation for planning purposes.