Numerical Simulation Of Suspended Sediment Transport In Estuarine Areas Under Wave-current Interactions

Sedimentation has become one of the major factors that restrict the development of economy in estuaries because it blocks navigation and lowers the flow capacity. Estuaries are dynamic zones of mixing between freshwater and oceanic water. Because of these competing forces, estuaries are seasonal erosion/deposition for suspended sediment, depending on the strength of the tidal and wave forcing. The response of estuarine geomorphology to future scenarios of climate change and sediment supply is difficult to evaluate, and must be performed with a robust, calibrated numerical model for sediment transport.In this paper, the fundamental principles for simulation of flow field and cohesive sediment transport in estuaries, using MIKE 21 software, is introduced. The HD model is based on the continuity equation of water flow and the incompressible Reynolds averaged Navier-Stokes equation; and the MT model is based on the advection-dispersion equation. The radiation stress acts as one of the driving forces for flow and sediment transport, flocculation and hindered settling are taken into consideration in the multi-layer and multi-fraction erosion and deposition simulation.A two-dimensional numerical model for sedimentation is set up to simulate the flow field and suspended sediment concentration distribution changes, based on the hydrographic and sediment data of the Majia River in several years, and it's calibrated with the observed current and suspended sediment data. To meet the flood control and water supply requirement, dredging, sluice and levee construction and are considered as river regulation schemes, and the flow capacity and sedimentation of the river are simulated in each case.With scarce previous researches on the sedimentation in the Majia estuary, there is little data about historical sedimentation and geomorphology. For the complexity of the sand transport and time limited, there are many aspects of the problem have not yet been taken into account, such as sudden silt, bed consolidation, and the long-tern erosion and sedimentation. There're more researches need to be done in the future.