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

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 practical significance for design of coastal engineering and minimization of damage during super typhoons.