The Tidal Flow and Dilute Diffusion of COD at Quanzhou Bay

The tidal circle and the dilute diffusion of the Chemical Oxygen Demand (COD) for neap tide were proposed with a two-dimensional mathematical model at Quanzhou Bay, which used an orthogonal curvilinear coordinate system. The computed results were in satisfactory agreement with the field data. It shows that the sewage effect for normal discharge to the water was not too severe. The range of the COD that exceeded Class square sea water quality standard was in a limited scope nearby the outlet, and the effect´s area are about 0.17 km², 0.31 km² and 0.05 km² at discharge outlet of Stone Lake, A and B, respectively. It would provide some advice to improve the sea water quality of the Quanzhou Bay and scientific management of the sewage discharge.