Estimating sediment deposition volume in a reservoir using the physiographic soil erosion-deposition model

A traditional way to estimate the amount of sediment deposition in a reservoir is simply based on the variation in the elevation measurements made at different times. In the present study, a physiographic soil erosion-deposition （PSED） model is applied to Tseng-Wen reservoir watershed to compute the discharge and sediment concentration into the reservoir, and the deposition volume. The PSED model is verified using three storm events and then compared to the historic data recorded at the hydrological stations in the reservoir watershed, which shows close agreement between the simulated and recorded values of the flow discharge into the reservoir and the corresponding sediment yield. The numerical simulation was also conducted for all rainfall events from 1996 to 2001 to estimate the annual sediment deposition volume in the reservoir. Similarly, the simulated result was compared to that obtained from the cross-section elevation measurement. It is found that some measured data points had large uncertainty or were questionable. On the contrary, the model results and the measured data that renders the model credible. Therefore, regardless of the estimation for the flow discharge into the reservoir induced by a single rainfall event, the sediment yield, or the sediment deposition, the PSED model has successfully demonstrated its ability.