The article analyses and predicts the hydrodynamic feature of study area on the basis of numerical model. By means of two-dimensional numerical simulation, computation on contribution concentration is used on the pollutant, which was discharged into Yangtze River by the factory of Baosteel Group Corporation in 2001, 2005 and 2009, and then paper assesses the influence of the discharged sewage on marine water quality nearby. This paper which takes CODcr of the wastewater as the research object does a comparative analysis on the influence caused by pollutants in wastewater on the Yangtze River's water quality from the point of time.
The factory of Baosteel Group Corporation locates near the offshore reaches of Baoshan District, Shanghai. Liu River in Jiangsu Province is at its north and Waigaoqiao Port in Pudong New Area is at its south. There are numerous factories and ports nearby. The sewage of outfalls of the company's (1#, 2#, 3#, 4# and the Baosteel Luojing Outfall) flows into the Yangtze River after being processed. Position of research area and location of the sewage of outfalls can be seen below in Fig 1.
In order to study the distribution of CODcr when sewage is discharging, using Mike21(FM) two-dimensional hydrodynamic module to simulate the tide currents of the Yangtze River. The model takes advantage of the modeling system. Mike21 system is a flexible, modular modeling system composed of a number of modules, Using it can investigate hydrodynamics, sediment transport, wave and water quality for fluvial, estuarine and coastal environments l (Chen et al., 2002).
For the topography of research sea is comparatively complex and coast is tortuous, a scalene-triangled computational grid is used in the model. The method of grid refinement is applied in crucial computational area.
