Numerical Simulation Of Evolution Of Estuary Sand Bar

The estuary is the junction of the sea and the land, and is part of the coastal zone. The estuary zone is effected by dynamic factors such as river run-off and ocean current. The typical topography and its formation of mouth bar and delta which locate on the estuary play an important role on the port sitting and channel dredging, and inextricably contact with people’s production and life.The tide hydrodynamic model is first used in this paper and coupled with the sediment transport rate equation and bed deformation equation. Numerical simulation is carried out to describe the formation and evolution of the estuary sand bar under estuarine runoff and coastal tidal currents. ADI scheme is used in this paper to discrete and solve shallow water equations, and fifth-order accuracy of the Euler-WENO scheme is also used for solving the equation of the underwater terrain, and flow and sediment coupled numerical model were compared. Then the model is verified by one-dimensional analytical of sand ridge evolution of Hudson and two-dimensional experiments of oval-shape shoal of Shieh.The model is used to simulate the evolution of estuary sand bar when the coastal slope is1:200. Calculation is carried out to simulate evolution of shoal under three different tide amplitude and three different river currents. Discussion has been given for influence of evolution under three different tides and three different river flows.To discuss what effect the estuary shape had been had on the formation and evolution of estuary sand bar, contrast which is for the description of estuary sand bar had been carried out under1:1、1:2、1:3ratio of river width to estuary width. To discuss the effect of coastal slope, evolution of estuary sand bar under1:50、1:100、1:200slopes is carried out, and contrast of them is given.Evolution of estuary sand bar under suspended load is discussed. ADI scheme is also used for the two-dimensional diffusion equation’s discretion and solving, and the concentration of suspended load is gained. Then it is superposed with the bed load evolution underwater terrain linearly, and the model of effect of suspended load and bed load is gained. Then calculation is carried out to contrast with the original result. At last, analysis and discussion is given for the results.