Mathematical Model Research of the Siltation Downstream Estuary Floodgate Under the Effect of Float Mud

The Jiao (Ling) River is a typical mountainous macrotidal river. The tidal current and runoff jointly guide sediment gathering in a specific section to form the turbidity maximum zone and develop fluid mud. This plays an important role in riverbed evolution. The construction of sluice in the mainstream of the Jiang (Ling) River will greatly change the original flow and sediment movement characteristics of the river channel, forming siltation downstream sluice and producing a big influence on flood control and drainage and navigation. The flow and sediment movement characteristics of Jiang (Ling) River are analyzed and the influence of fine-grained cohesive sediment movement characteristics and salinity considered. A flow and sediment mathematical model for sluice construction in the Jiang (Ling) River is established to simulate the hydrodynamic change and the temporal and spatial distribution characteristics of sedimentation after the sluice construction. The research results show that the sluice construction has an influence on the entire channel downstream sluice. The closer to the sluice site, the bigger the influence will be. At the initial stage of sluice construction, sediment is mainly deposited in a deep trench of 10 km downstream sluice. The siltation downstream sluice will elevate the flood level and low water level, thus affecting flood control and drainage. It will also decrease the water depth of the channel, thus reducing the navigation capacity of the Jiao (Ling) River. The research results have improved the simulation accuracy of sediment transport mathematical model in the estuary with sluice constructed and provided reference for similar sluice construction in estuaries.