Analyzing the relationship among the return periods of rainfall tide surge and flooding

Abstract

For coastal areas storm surge and rainfall are important factors that cause flooding but these two factors are not completely related When a typhoon event occurs heavy rainfall and storm surges usually accompany it However when rains are caused by rainy season or southwest air they do not necessarily cause storm surge at the same time In other words in estimating the frequency of flooding in coastal areas the relationship between storm surge and rainfall must be considered otherwise bias will easily occur In this study the events were selected in three scenarios and the flooding depth and the number of people affected by each event were calculated with the hydraulic model Scenario –R selects the 24-hour maximum rainfall of each year and the corresponding tide level during its occurrence period as the input data; Scenario-T selects the maximum tide level of each year and corresponding rainfall during its occurrence period as the input data; Scenario-Max Select the largest of the flooding depth and the number of people affected by Scenario-R and Scenario-T The results show that compared with Scenario-Max the frequency analysis of Scenario-R or Scenario-T will overestimate the depth of flooding and the probability of people affected Therefore when evaluating the flooding impact of a specific return period in coastal areas if only consider the probability of rainfall or tide level and the combined effect of the two factors is not considered it will cause a serious underestimation

Date of Award	2020
Original language	English
Supervisor	Jiun-Huei Jang (Supervisor)