Modeling sediment concentration and transport induced by storm surge in Hengmen Eastern Access Channel

Abstract

Sediment is an important factor for excavation, dredging and maintenance of Hengmen Eastern Access Channel in Pearl River Estuary. As storm surge is considered as an important role in determining sediment re-suspension and transport, as well as creating landforms in the areas of estuary and coast, along with the storm surge disaster damage in Pearl River Estuary is one of the most serious events in China, reasonable simulation of storm-induced sediment concentration, transport and channel siltation in Hengmen Eastern Access Channel is of much significance. Based on the feasibility condition of less research on numerical simulation of storm-induced sediment concentration and transport, especially channel siltation in the Pearl River Estuary, using a curvilinear grid, a nested and coupled model which combines typhoon model, hydrodynamic model (Delft3D-FLOW), wave model (Delft3D-WAVE) and sediment transport model (Delft3D-SED) was set up for the region of Pearl River Estuary. After a series of model verifications, which showed that this coupled model performed well to reflect the characteristics of the typhoon field, tidal currents, wave height, storm surge, distribution of suspended sediment in the studied region, the model was applied to study the storm-induced sediment concentration and transport in Hengmen Eastern Access Channel. Through simulation of one extra tropical storm surge process with this coupled numerical model, the storm-induced sediment concentration and transport in Hengmen Eastern Access Channel were studied, and the storm-induced erosion and deposition were further discussed. Results showed that the effect of storm surge on sediment concentration, transport and siltation was significant. Under the influence of storm surge, the velocity and bed stress around Hengmen Eastern Access Channel increased significantly, which led the re-suspension and transport of sediment, and thus, the higher sediment concentration and more channel siltation occurred. By running this coupled model, the simulated results can be employed in the optimum decision making of Hengmen Eastern Access Channel Regulation Project.