The Research Of Longshore Currents Effects On Estuary And Bay Evolution

The longshore current has an important influence on the evolution of tidal channel,and it is of great significance to study the influence of longshire currrent on the topographic evolution of this region,such as shoreline protection and waterway dredging.In this paper,the effects of longshore current on tidal channel geomorphologic evolution are studied by numerical simulation.First of all,this paper introduces the calculation of numerical model,including hydrodynamic model,sediment transportation model and terrain evolution model.The hydrodynamic model is a coupled computing model considering hydrodynamic force of wave and tide,as well this paper introduces calculation method and calculation process.In order to ensure the accuracy of the numerical results,the numerical model is verified in this paper,and hydrodynamic model is compared with Mike simulation results and experiment data,the sediment transport model simulation results is compared with analytical solution,the terrain evolution model is validated by comparing with the result verified by others.Then,this paper analyzes the effects of longshore currents on estuary and lagoon flow field and topographical evolution.The results show that there are obvious interactions between longshore currents with runoff,and longshore currents with tide.The topographical evolution caused by longshore currents and runoff is approximately equal to the sum of each one.The effects of longshore currents on the lagoon landform evolution include nearshore area of concave and convex caused by longshore sediment transportation and deep groove caused by suspended load sediment transportation which is driven by longshore currents and tide.Finally,applying the numerical model established in this paper to simulate Shuidong Bay.By comparing the evolution of terrain features caused by tide and tide with longshore current,to analysis effects of longshore currents on evolution of Shuidong Bay.