超强台风作用下钱塘江河口的台风浪计算

Calculation of typhoon-generated wave due to a super typhoon in Qiantang Estuary

基于SWAN波浪传播模型建立包含风暴潮与天文潮耦合传播的台风浪数值模型,将1949年以来登陆我国大陆沿海最强的5612#台风作为典型的超强台风,计算了超强台风沿中线和北线路径登陆遭遇天文潮高潮位时产生的沿海波高过程。结果显示:河口波高总体分布下游大于上游,北岸大于南岸,两岸代表断面堤前最大有效波高可达5.5m;中线路径生成的近岸台风浪波高为单峰过程,北线路径时北岸的波高出现双峰过程,波高峰值与风暴高潮位并非总是同步出现,两者时间差最大为4h;根据频率曲线分析,中线、北线路径超强台风作用下乍浦站台风浪的重现期分别为135a和350a;中潮时的近岸台风浪波高比大潮降低0.1～0.2m,小潮时再比中潮降低同样幅度。这些结论对海堤工程设计和防灾减灾具有重要意义。

A numerical model of typhoon-generated wave based on SWAN model, including the coupled propagation of astronomical tide and storm surge, is built. Typhoon No. 5612, the most intense to land in China since 1949, is taken as the typical super typhoon for the middle and north typhoon routes. The typhoon-generated wave process along the coast is calculated by the model under the conditions of typical typhoons coinciding with the high tidal level when they lands. The results show that the wave height is greater downstream than upperstream, and along north shore than along south shore. The maximal significant wave height is 5. 5 m along both shores in front of sea wall at the representative section. The typhoon-generated wave height is a process with single peak in the middle route, and with double peaks along the north shore in the north route. The high storm surge and wave peak do not always occur simultaneously, with a maximal interval about 4 hours. According to the analysis of the frequency curve, the return periods of the super-typhoon-generated wave at Zhapu Station are 135 years and 350 years in the middle route and north route, respectively. The typhoon-generated wave heights of the middle tide and neap tide are 0. 1-0.2 m lower than those of the spring tide and middle tide, respectively. The results have practi- cal significance for design of coastal engineering and minimization of damage during super typhoons.