Study of back silting characteristics and mechanism of the channel-mouth bar under the influence of regulating project: a case study of the Sheyang Estuary

Based on the measured terrain in different stages, the distribution characteristics of back silting in the Sheyang Port channel was analyzed. Velocity and sediment characteristics in Sheyang Port channel were calculated and analyzed by mathematical model. The reasons accounting for back silting in the waterway were discussed. The study showed that there is a widespread deposition in the channel after the channel engineering excavation, especially in the area near the mouth. The main reason of siltation in the channel is that the flood current speed is greater than that of ebb, so sediment is difficult to be taken out of the channel, which attributes to deposition of the channel. There are two reasons contributing to the back silting in estuary. Firstly, large amounts of sediment cross over the southern dike and go into the entrance of channel. In addition, there is an evident recirculation zone in the entrance channel during flood tide, which is easy to lead to gate sediment deposition. The reason for silting near the root of dike is the decrease of estuarine water carrying capacity during ebb tide, which is attributed to the river relaxation resulting from confluence of Sheyang River and Huangsha River.