A three-dimensional pollutant transport model in orthogonal curvilinear and sigma coordinate system for Pearl river estuary

In this paper, the development of a three-dimensional numerical pollutant transport model, which is coupled with a previously developed hydrodynamic model, is delineated in details. Special features of the model include orthogonal curvilinear coordinate in the horizontal direction and sigma coordinate in the vertical direction. Besides, a simple but efficient open boundary condition of pollutant transport is adopted. It is then applied to simulate the transport of a representative water quality parameter chemical oxygen demand in Manganese (CODMn) in the Pearl river estuary, which is the largest estuary in South China. It can be shown, from the simulated results, that there exists a transboundary action between Guangdong province and Hong Kong special administrative region for the pollutants in the wastewater discharged from Pearl river delta region.