Sediment Delivery Ratio on Sediment Event Scale: Quantification for the Three Gorges Reservoir

The Three Gorges Reservoir (TGR) is an important project in Yangtze River, China. The sediment deposition can cause reservoir capacity loss, which goes against the maximization of TGR’s interests. Therefore, the research on sediment delivery problem of the TGR is vital for its sustainable and efficient use. However, the observation data of the TGR covers only 15 years, which is not enough for the analysis of sediment delivery ratio (SDR). This paper was based on the analysis of observation data, employed the 1D Flow-Sediment numerical model to simulate plenty of cases of sediment delivery in TGR. Based on these simulation results on sediment event scale, a regression relationship of SDR was established and the influencing factors of SDR were discussed. Two types of factors which were the flood detention time (FDT) and the inflow sediment coefficient (S_in/Q_in), were ascribed to the main factors. In addition, the regressive formula of SDR was verified by the observation data of the TGR. This study would highlight the sediment transport characteristics on the scale of sediment event in the TGR and contribute to the TGR’s capacity maintenance.