Numerical Experiment on Salt Transport Mechanism of Salt Intrusion in Estuarine Area

The process of exchange and transport between salt and fresh water is affected by not only convection due to the density gradient but also turbulence. In this study, a high resolution mathematical model of the intrusion movement of saltwater in an estuary area was established and compared with a physical flume experiment. The model, whose minimum horizontal grid cell of the model is 0.05 m, and minimum vertical grid cell is 0.0005 m, simulated well the salt transport mechanism at the interface between salt and fresh water. The salt transport processes of estuarine saltwater intrusion were obtained under the conditions of no runoff and no tide, no runoff and tide, and runoff and tide. The results suggest that under the joint action of runoff and tide, the mixing process in the interface of salt and fresh water is relatively gentle, the change in the velocity gradient is small, and the advance distance of saltwater intrusion will reach a dynamic equilibrium state after a period of time.

Automated summary

A high resolution mathematical model was established to simulate the intrusion movement of saltwater in an estuary area, and its accuracy was confirmed by comparing it with a physical flume experiment. The results indicate that under the combined action of runoff and tide, the advance distance of saltwater intrusion will reach a dynamic equilibrium state.