Analysis of pollutant transport in the Han River with tidal current using a 2D finite element model

Pollutant transport in the Han River, which is one of the most important rivers in Korea, was studied using the 2D advection-dispersion model developed in this research. The numerical model was developed based on the streamline-upwind Petrov-Galerkin (SUPG) where a finite element grid was used in order to treat the complex geometry of the natural water bodies. Velocity fields for the input data of pollutant transport simulation were obtained using a 2D hydrodynamic model, RMA2. The pollutant transport simulations in both the steady state flow and in the tidal currents were carried out to analyze the effects of tidal currents on the 2D concentration distribution in the region of application. The simulation results show that, with increasing water level period under tidal conditions, very large recirculation zones occurs and water flows in the upstream direction. Therefore, within the tidal currents, the polluted water goes back and forth with variations in the flow direction. As a result of this movement of pollutant, an oscillation in the concentration appears over time, which reflects both the significantly complex periodic variation in the flow pattern and large circulations.