A three-dimensional contaminant transport model of heavy metal (copper) was coupled with the hydrodynamics and suspended sediment transport module to simulate the transport and distribution of heavy metal (copper) of the Danshui River estuarine system in northern Taiwan. The coupled model was validated with observational data including the water level, tidal current, salinity, suspended sediment concentration, and copper concentration. The model simulation results quantitatively reproduce the measurements. Furthermore, the validated model was employed to explore the influences of the freshwater discharge and suspended sediment on the distribution of copper concentrations in the tidal estuarine system. The results demonstrate that a high freshwater discharge results in a decreasing copper concentration, while a low freshwater discharge raises the copper concentration along the estuarine system. If the suspended sediment transport module was excluded in the model simulations, the predicted copper concentration underestimated the measured data. The distribution of copper concentrations without the suspended sediment transport module was lower than that with the suspended sediment transport module. The simulated results indicate that the freshwater discharge and suspended sediment play crucial roles in affecting the distribution of copper concentrations in the tidal estuarine system.
Keywords: Copper; Hydrodynamics; Salinity; Suspended sediment; Three-dimensional model; Tidal estuarine system.