台风对近岸复合洪水的影响评估

Assessing the Effects of Typhoon on Compound Flooding in Coastal River Areas

不同特性的台风在多大程度上导致与强降水和风暴潮相关的近岸复合洪水尚不清楚,为厘清近岸台风事件与复合洪灾的相互关系,以中国东南沿海为研究典型,基于降水和风暴潮数据,分析1980—2019年复合洪水驱动因子依赖性,利用copula统计模型描绘复合洪水回归期,通过定量评估表明台风对复合洪水潜势升级发挥重要作用。研究表明:(1)中国南方沿海地区复合洪水潜力高于北方,降水与风暴潮之间的依赖性是影响复合洪水发生的关键;(2)台风一方面增强极端降水和极端风暴潮之间的依赖性,使广西、广东阳江、浙江沿海复合洪水潜势增加10%~30%,另一方面提高了极端降水和风暴潮的发生边际概率,使闽苏、海南、澳门地区复合洪水概率增加了50%~180%。(3)相对而言,台风诱发的风暴潮比台风诱发的降水更能放大复合洪水潜势;(4)根据灾害损失分析,台风期间复合事件所造成的损失远大于单驱洪水事件。研究成果可为台风对近岸复合洪水的风险决策及防灾规划提供科学依据。

It is not clear to what extent typhoons with different characteristics contribute to nearshore compound flooding associated with heavy rainfall and storm surges.To clarify the relationship between nearshore typhoon events and compound flood disasters,a study is conducted on the southeast coast of China from 1980 to 2019.Based on precipitation and storm surge data,the dependence of drivers of compound flooding is analyzed.The copula statistical model is used to describe the return period of compound flooding,construct scenarios,and quantitatively evaluate the results,indicating that typhoons play an important role in increasing the potential for compound flooding.The results show that:(1)The compound flood potential in the southern coastal areas of China was higher than that in the northern,and the dependence between precipitation and storm surge is the key to the occurrence of compound flood;(2)On one hand typhoons increased the dependence of extreme precipitation and storm surges,increasing the potential for compound flooding by 10%-30%in Guangxi,Guangdong Yang Jiang,and Zhejiang coastal areas;On the other hand,typhoons increased the probability of compound flooding by 50%-180%in Fujian-Suzhou,Hainan,and Macao region;(3)Relatively,typhoon-induced storm surge can amplify compound flood potential more than typhoon-induced precipitation;(4)According to the typhoon loss records,it is found that the losses and casualties during typhoons with compound events are the vast majority compared to single flood events.The research results can provide scientific basis for the risk decision-making and disaster prevention planning of the compound flood caused by typhoon.