Simulation Of Flow And Solute Transport In Estuary Region Based On Remote Sensing And Numerical Simulation

It has been a long history since human began the development and utilization of the estuary regions, which is still of the most intensive economic activities, the densest population and the profoundest impact of environmental change on the world until now. However, with the rapid development of economy, environment of estuary regions are interrupted by intensive human activities, impeding the sustainable development of the estuary regions. A systematic and scientific simulation and analysis on estuarial water environment is of great importance for the planning and management of the quality of water environment in the future.In this thesis, it is mainly studied the hydrodynamic behavior and water quality condition of Sheyang Estuary area based on in situ observation there on July 2007. According to the calculation and analysis of tidal current and water quality on Sheyang Estuary region, the characteristic of tidal field and thereby the diffusion of water quality elements are studied. The research of this thesis has both theoretical and practical significance to water environment protection of Sheyang Estuary and the adjacent sea areas. Main contents and achievements of the thesis are as follows:1. Based on observation data and lots of references, after many times of experiments and adjustments, relative hydrodynamic and water quality parameters of EFDC model for the study area are determined, which sets up basis for the simulation of hydrodynamic and water quality condition in the next step. The retrieval of sea surface temperature by remote sending image is adopted to obtain the sea surface temperature of Sheyang Estuary. By atmospheric and geometric modification of the remote sensing image, and based on wave band calculation on thermal infrared wave band, sea surface temperature of Sheyang Estuary is obtained. This method reasonably depicts the variation of sea surface temperature, and provides sufficient data for the determination of temperature field in the model.2. On the comparison of flow rate and flow direction between calculation and observation at tide gauging station and observation plot, it is concluded that the model can both depict tidal fluctuation process and capture fairly well the distribution and variation of tidal current at Sheyang Estuary where the coastal line and topography are very complex. Results of simulation reveal that there are some differences in vertical flow field, that is, flow rate of lower layer is obviously smaller than that of the upper layer, which is a result of the compound function of friction at the bottom and vertical mixture of turbulence. Therefore a 3D simulation model should be applied to simulate flow field in Sheyang Estuary, to fully take into consideration the effect of runoff.3. Distribution of water quality in Sheyang Estuary area is simulated by the established water quality model, which reveals fairly high precision by residual analysis. It is indicated that pollutant mainly comes from runoff input, the density of degradable organic nitrogen particle and dissolvable organic nitrogen show a decline trend from the river mouth outwards.4. Research results reveal that the incidence to pollutant source to water body is mainly close to the pollutant source, while expand gradually with time. The hydrodynamic condition of the study advantages the dilution and diffusion of pollutant. As a typical estuary in Jiangsu Province, the total pollutant discharge at Sheyang Estuary ranks the second after north branch of Yangtze River among all the 23 rivers that flow to the sea in Jiangsu Province, therefore the research on hydrodynamic process and water quality condition of this region is of great importance to understand the human impact on eco-environment of coastal sea areas.