台风“米娜”影响下的杭州湾风暴潮特征及对咸潮的影响

The characteristics of storm surge under the influence of Typhoon"Mitag"and its effect on salt-tide intrusion in Hangzhou Bay

基于2019年台风“米娜”风暴潮期间的实测资料,应用ADCIRC海洋模型,开展杭州湾周边海域台风风暴潮数值模拟,刻画台风期间杭州湾海域风暴增减水过程及其时空分布,并分析杭州湾风暴增减水特征以及对钱塘江咸潮入侵的影响。结果显示:芦潮港、滩浒、岱山和沈家门这4个验潮站模拟天文潮位的平均绝对误差分别为22 cm、19 cm、10 cm和14 cm,最大风暴增水的绝对误差分别为6 cm、1 cm、6 cm和7 cm,模型模拟结果良好。台风影响期间,杭州湾(湾底)的风暴增水明显大于(湾口)岛屿,滩浒站最大增水为111 cm,沈家门站最大增水为74 cm;舟山外海—杭州湾的天文潮-风暴潮的非线性作用逐渐增大,在风暴增水达到最大的过程中,各站天文潮-风暴潮的非线性作用分别为24 cm、26 cm、14 cm和4 cm;钱塘江咸潮入侵程度主要取决于径流和潮汐强度,风暴增水会在一定程度上加剧咸潮入侵灾害,在台风“米娜”风暴增水期间,钱塘江发生咸潮入侵,造成南星水厂氯度值超标41 h,因此在台风影响期间需要提前预判风暴潮对咸潮入侵的影响,做好科学应对。

Based on the observations during Typhoon"Mitag"in 2019,numerical simulation of typhoon storm surge around Hangzhou Bay has been carried out by using the ADCIRC model,to analyze the storm surge process and its characteristics in Hangzhou Bay,as well as its influence on the salt-tide intrusion of the Qiantang River.The results show that:The mean absolute errors of the simulated astronomical tide at Luchao Port,Tanxu,Daishan and Shenjiamen tide stations are 22 cm,19 cm,10 cm and 14 cm,respectively.The absolute errors of maximum storm surge are 6 cm,1 cm,6 cm and 7 cm,respectively.The storm surge in Hangzhou Bay is stronger than that of the outside islands during the typhoon.The maximum storm surge at Tanxu station is 111 cm,and that at Shenjiamen station is 74 cm.The non-linear interaction between astronomical tide and storm surge increases gradually from Zhoushan offshore to Hangzhou Bay.When the storm surge reaches its maximum,the non-linear interaction at each station are 24 cm,26 cm,14 cm and 4 cm,respectively.The salt-tide intrusion of Qiantang River mainly depends on runoff and tidal intensity,storm surge aggravates the salt-tide intrusion,and the salt-tide intrude the Qiantang River during Typhoon"Mitag",causing the chlorinity exceeding the limit of 41 hours at the Nanxing Water Plant.It is necessary to predict the influence of storm surge on salt-tide intrusion during typhoon and to make scientific countermeasures.