不同路径台风作用下长江下游沿线风暴增水分布研究

Study of storm surge distribution along the Yangtze River and Estuary under different typhoon tracks

长江口受台风影响严重,台风风暴潮、上游洪峰及天文大潮相遇将致使长江下游至长江口水位暴涨,对沿岸至河口的防汛安全构成严重威胁。基于ADCIRC模型构建东中国海至长江口风暴潮数学模型,模拟9711号台风和0012号台风两场典型台风水位过程。以典型台风为基础构成多种台风路径,分析不同登陆位置和走向对长江沿线风暴增水影响。研究大洪水、不同路径台风、天文大潮共同影响下长江下游沿线风暴增水分布规律。结果表明:登陆位置处于长江口南侧情况下长江河道沿线增水大于正面登陆长江口和北侧登陆型台风;平行于长江河道方向移动的台风造成沿线增水大于斜向穿越长江口的台风,不同台风走向对于风暴增水影响程度小于登陆位置;台风风暴潮、上游洪峰及天文大潮“三碰头”情形下长江沿线增水分布呈单峰型,从大通至江阴不断增大,江阴至中浚维持高位,中浚至口外迅速减小。

The Yangtze Estuary is among the areas most vulnerable to typhoon,the encounter of typhoon-induced storm surge,upstream runoff and astronomical high tide combine to cause extremely high water level along the Yangtze River,posing a big threat to the lower reaches of Yangtze River and Estuary in terms of flood prevention.Based on the advanced circulation(ADCIRC)model,a storm surge model from Datong station to the East China Sea is established.Typical hypothetical typhoons with different landing locations and moving directions are constructed,based on Typhoon 9711 and typhoon 0012,the influences of typhoon tracks on storm surge are studied.Distribution of storm surge under different typhoon tracks along the Yangtze River are analyzed,under the combinations of extreme typhoon storm surges,maximum runoff and high astronomical tides.The results show that typhoons landing on the southern end of Yangtze Estuary generate the larger surge than typhoons landing on the Yangtze estuary directly or on its northern side;typhoons moving westward after landing tend to generate larger surge than typhoons moving northward;the influence of moving direction is smaller than land location.The storm surge induced by the combined impact of runoff,offshore astronomical tides and storm surges are distributed in a hump-like way from Datong to the estuary area,increase from Datong to Jiangyin section,change a little between Jiangyin and Zhongjun,then decrease in below Zhongjun downwards.