超强台风“威马逊”作用下红河三角洲海域水动力环境变化的数值研究

Numerical modeling of hydrodynamic changes due to super Typhoon Rammasun in the Red River Delta coastal area

201409号超强台风"威马逊"于2014年7月从北部湾北部过境,对红河三角洲近岸海域的水动力环境产生重要影响。本文基于Delft3D建立三维潮、流、浪耦合数值模型,对红河三角洲水位、海流及波浪对台风的响应变化进行模拟。结果表明:威马逊台风期间,红河三角洲海域风速增大约6倍,风向由偏南风转为偏北风,表底层流速均受影响,其中表层变化较大,表现为北分量流速明显增大,流向变为偏南向,与风向主分量变化有关;波高增大为正常海况的9倍,时间变化与风速一致。本研究获得了从北部湾北部海域过境的台风影响下红河三角洲海域水动力环境的响应变化特征,对该海域的物质输运研究及海洋工程建设有重要意义。

The Red River Delta in the Gulf of Tonkin is located in a complex tidal estuary that has many channels and shoals and is frequently affected by typhoons.A coupled numerical model based on Delft3 d was established,and the model was validated using in situ survey data,which was used to simulate the hydrodynamic changes occurring in the coastal waters of the Red River Delta due to Typhoon Rammasun.The wind speed of the typhoon was 6-fold faster than the average wind speed,and during the typhoon’s movements,the wind direction changed from southerly to northerly.The currents at the surface and bottom layers are affected by strong winds in which the north component velocity was strengthened and direction changed from northwardly to southwardly,especially at the surface layer.The simulated significant wave height in the Red River Delta coastal area increased 9-fold during a typhoon period,and the time phase of the simulated significant wave height was consistent with the changes in the wind velocity of the typhoon.This work describes the hydrodynamic changes induced by a typhoon moving through the northern Tonkin Gulf,which will support studies on sediment transportation and marine engineering construction.