Encounter Risk Analysis of Rainfall and Tide in Shenzhen Based on Copula Function

The disasters of encounter of extreme rainstorm and high tide level will aggravate the flood in coastal cities.In order to explore the impact of the encounter of rainstorm and tide on flood control and drainage in coastal cities,based on the annual maximum 1 day rainfall and its corresponding tide level data of Chiwan Station in Shenzhen from 1967 to 2018,the Copula function is used to construct a joint distribution model of annual maximum 1 day rainfall and its corresponding tide level,and the co-occurrence risk,the flood control risk,the condition risk and the combination risk of rain and tide in Shenzhen are calculated and analyzed.The results show that the risk of the encounter of rain and tide in Shenzhen is small,and the co-occurrence and combination risk probability of rainfall whose return period greater than 100 years and tidal level whose return period greater than 200 years are only 0.12% and 0.09%.The probability of the occurrence of rainfall or tide exceeding the standard magnitude is 1.09%,and its return period is less than 100 years.When the rainfall exceeds the standard magnitude,the probability of encountering an over-standard tide level is greater,with a probability of 12.33%.At the same time,with the increase of rainfall,the risk will also increase.Therefore,in the planning and design of flood and tide prevention and drainage in cities,the focus should be on attention and prevention.