Transport laws for pollutants in coastal area of Lianyungang City

To study the variation laws of transport and concentration increment of pollutants in the coastal area of Lianyungang City under tidal motion,the sewage discharge of two newly-built sewage treatment plants in Xuwei Development Area of Lianyungang City was taken as a study case.A coupled hydrodynamic and water quality numerical model was established based on the unsteady shallow water equations and the vertically averaged 2-D convection-diffusion equations.The finite volume method was employed to discretize and solve the model on unstructured triangular mesh.The tidal levels of neap tides and spring tides on the open boundaries were generated by means of the TPXO tide model.The results indicate that the proposed model can be employed to satisfactorily simulate the hydrodynamic flow fields and the transport loci of pollutants in the coastal area of Lianyungang City under different hydrologic conditions.The concentration increment is proportional to the sewage discharge and inversely proportional to both the flow velocity and the water quantity,and the concentration increment of pollutants at slack of neap tides is relatively the largest.