The Influence of Wind and Waves on Saltwater Intrusion in the Yangtze Estuary: A Numerical Modeling Study

Saltwater intrusion occurs frequently in the Yangtze Estuary during winter, when the river discharges are low along with strong wind and waves. However, the influence of wind and waves on saltwater intrusion in the Yangtze Estuary remains unclear. This study uses a coupled wind-wave-current numerical model based on Delft3D to investigate the impacts of wind and waves on saltwater intrusion in the Yangtze Estuary. The results show that the strong northerly wind alone enhances saltwater intrusion in the estuary by inducing a counterclockwise circulation and reducing the stratification. However, with the combined effect from wind and waves, it is found that stratification is reduced in the outer North Channel, but enhanced in the inner North Channel, which results in an increase of salt transport in the estuary by approximately 40%. The results highlight the fact that saltwater intrusion in the Yangtze Estuary could be significantly underestimated without considering waves.