Study And Application Of Three-Dimensional Hydrodynamic And Mass Transport Numerical Simulation In The Coastal Area And Lake

Recently, people paid more attention to the environmental problem in the shallow sea and lake. Coastal zone and estuary are the intersection of land and water. They have complex dynamic conditions. Lake is one of the most important resource. It is important to study the three dimensional dynamic and sediment transport in the coastal area and Lake.To study the Oujiang River Estuary (ORE) with multi-islands, complex topography and flow patterns, the model was applied to the simulation on tidal field and salinity field in the Oujiang Estuary. The parameters are calibrated and verified using observational data. The simulation results agree with measured data well. The model data-comparisons are water elevation, velocity, and salinity. According to the simulation results, the characteristics of tidal flow and salinity in Oujiang Estuary are analyzed. The results indicate the alternating currents are obvious in the region of nearshore, estuary and Yueqing Bay, the father offshore the more obvious rotary currents. The salinity is mixed on the vertical distribution in the estuary. The tidal current and salinity field in Oujiang Estuary is re-acted successfully, the model can be applied in estuary and coastal regions.Numerical simulations of the wind-driven current in Taihu Lake are performed by Environmental Fluid Dynamics Code (EFDC), the simulation results accord approximately with the observed water level. It is shown that the model is applicable to simulate the Taihu flow field. The influence of different wind field,topography and inflow/outflow on the flow characteristics of Taihu. According to the comparison of varied scenarios, wind plays a vital role in flow structure of Taihu, and it is the most sensitive factor; The topography of lake bottom significantly affects the flow field at different levels; Inflow/outflow affects flow field faintly. Under the windless condition, The flow is mainly drived by inflow and outflow which has a defined influence on the flow-patten in the vicinity of the inflow and outflow of the lake.The QuikSCAT/NCEP blended wind data is used as the input wind field of SWAN in the modeling of waves in the Bohai Sea. And the simulated data agree with the field observation in the Bohai Sea. The flow field and wave field are simulated and analyzed under the action of different prevailing winds (wind speed is 6.5 m/s,8 m/s, wind direction is SE, NW) in Taihu Lake, the reliability of the results is verified by comparing simulation results with previous researches. The variations of current, salt intrusion, and vertical stratification under different river flow and wind conditions in the Oujiang River Estuary were investigated in this paper using the EFDC. The model was verified against water level variation, velocity, and salinity variations in June 2005. The simulation results agree with measured data well. Six sensitivity tests were conducted with different river flow and wind conditions specified in the model. Model results show that salinity intruded further upstream under scenarios with low flow, downriver local wind conditions. In contrast, the responses of salinity stratification to different environmental forcing functions were different in different portions of the estuary. Salinity stratification was enhanced under high flow condition. Model results also show that wind is not crucial to the salt intrusion and salinity stratification in the ORE.The wind-wave and current forcings are critical for the sediment resuspension and deposition processes. The bottom shear stresses, generated by wind-wave and water current, are used to drive sediment resuspension/deposition in a water column. The model applies the newly developed WCM to calculate total bottom shear stresses. Then combining wind wave, current and the sediment model together, the sediment transport model for sediment transport under the combined action of wind, wave and current was developed. The model was applied to simulate the hydrodynamics and sediment transport at the Oujiang Estuary. The model reasonably predicted the dynamic variance of SSC.