A 2D Numerical Simulation Of Suspended Sediment In The Taizhou Bay

"Waves lift sediments and currents transport them" is the sediment transport mechanism in the coast and estuary where both waves and currents play great roles. The Taizhou Bay is not just a macro-tidal coast, but a strong-waves area. Study on suspended sediment transport and the transport rules in the Taizhou Bay can not only provide the basis for coastal engineering and let us know the evolution of estuarine and coast, but play an important part in the protection of the marine environment.Based on the existing hydrodynamics, sand transport theory and numerical calculation method, a 2D depth-integrated mathematical model which combined wave with current on suspended sediment in the Taizhou Bay is developed. There are three parts in this model, a 2D compound hydrodynamics model combined waves and currents, a wave-model and a 2D suspended sediment transport model. The wave radiation stress is considered in the compound hydrodynamic model. The value of bottom friction is offered by the wave-current bottom boundary layer model. In the sediment transport model, the. method of shear stress is adopted to determine the source function in the suspended sediment diffusion equation. The simulated results which include the coupling current model and the sediment transport model tally well with the measured data. It shows that the models that were built are in agreement with the fact of the Taizhou Bay basically.Then, temporal changes of suspended sediment concentration in the Taizhou Bay is analyzed. At the same time the distribution of suspended sediment during the spring-tide is compared and discussed under two conditions including pure current and wave-current condition. It indicates that the suspended sediment concentration in the Taizhou Bay show a neap-spring tidal cycle and flood-ebb fluctuations. During the spring-tide the concentrations of sediment increase from the Taizhou Bay to the Jiaojiang mouth, the condition of neap-tide is on the contrary, and the spring-tide concentration of suspended sediment is greater than the neap-tide concentration. In the mouth of Jiaojiang river the contributions of sediment concentration have little difference in two conditions which are pure current and wave-current motion. So it shows that in those areas suspension and resuspension of sediment are controlled by currents, and waves contribution is tiny; at the deep zone waves also have little effects. But in the shallow areas of Taizhou Bay waves play a very important part in sediment suspension and resuspension, suspended sediment concentration is 75% at least in wave-current greater than pure current condition. Then it shows that for Taizhou Bay which is a macro-tidal area waves play an important part in suspension of sediment.