The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

Yangshan Deepwater Harbor is characterized by numerous islands and complex terrain, and holds substantial economic importance for the Yangtze River Delta and China. This study investigates the residual currents and water flux in the harbor, adopting a high-resolution FVCOM model. The influence of the coastline and bathymetry changes due to the construction project and effect of Typhoon “Muifa” are discussed.
The results show that the inner and outer sides of East Entrance exhibit residual currents in opposite directions, resulting in a "residual current separation" phenomenon; In the northwestern sea area, a directional deviation is observed between the bottom and surface residual currents. The net water flux presents flow into the harbor from the East Entrance and flow outside through the other four passages. More detailed, the water flux in the Kezhushan Passage exhibit a distinct spatial structure, water flow into the harbor through the western side, but flow outward through the eastern side. The residual water flux in the five passages exhibit a remarkable spring-neap cycle, with limited residual water flux during neap tide but prominent residual water flux during spring tide.

The strong winds during tropical cyclones can strongly modulate the patterns of residual current and net water flux in the Yangshan Deepwater Harbor. The net water flux in the Kezhushan Passage was converted from a quasi-balanced state to significant outflow.

There are three key passages are closed by the construction of Yangshan Deepwater, which strongly modified the local coastlines and altered the pattern of residual current in local area. The constructions bring about stronger current in the remaining five passages and result in more water flux through them. Moreover, the constructions turned the Kezhushan Passage from outflow to inflow, and change the East Entrance from a quasi-balance state to outflow.

These findings reveal the characteristics of residual current and water flux in the Yangshan Deepwater Harbor. The insights provided by this study offer valuable guidance for future harbor management and possible constructions.
 

water flux, Yangshan Deepwater Harbor, FVCOM, tropical cyclone, human activities