153 / 2024-02-22 09:49:55

Numerical study on the influence of river discharge and wind direction on the flow split ratio of the Yangtze Estuary

the Yangtze Estuary,hydrodynamic characteristics,river discharge,wind-stress,ebb and flow,average velocity

The nearshore and estuarine areas are located in the connecting zone between ocean and land, which is the area of key urban construction, population gathering and rapid industrial and economic development. The Yangtze Estuary is a typical three-level branch estuary. The runoff movement in the mouth of the Yangtze River is coupled with the tidal movement of the east China Sea from the East China Sea to the sea, becoming the "sink" of the material flux in the basin and the "source" of the material flux into the ocean.

A high-resolution numerical model for the Yangtze Estuary based on the Danish MIKE21 hydrodynamic software is established in this study.. This model is well validated by vast of observed tidal levels and currents. We then design numerical experiments with 5 different discharge levels (average, minimal, maximal, 20% and 70% of the historical records), and 3 different wind directions with wind speed of 10 m/s (Climatic state summer wind direction, winter wind direction and positive north wind to) to investigate their influence on the water flux of the Yangtze Estuary. Results show that the ebb and flood water flux tend to increase with discharge in each branch of the Yangtze Estuary. the North Branch, the North Channel, the North Passage. Although the control effect of the North Branch during the spring tide is obvious, the influence of river discharge cannot be completely ignored, the net flux is negative, the ratio of the high tide of the North Branch, the greater the upstream runoff through the South Branch, and at the height of the high tide, the greater the river discharge, the increase from the North Branch; The change range of the high tide diversion ratio in the South Channel tide period is significantly greater than that of the diversion ratio in the low tide period; The variation rate of the diversion ratio of the South Channel section is smaller than that of the North Channel section.