Analysis of Risk Probability for Design Rainstorm Combinations of Different Durations

Based on the Copula theory and method,the joint probability distribution models between annual maximum daily rainstorm and three-day or seven-day rainstorm amounts were build with the maximum daily rainstorm as a reference using the daily rainfall data in Guangzhou City from 1951 to 2010 as a case study.Firstly,the Gumbel-Hougaard Copula function selected by the goodness-of-fit test was used to build the joint distributions which are the marginal distributions of generalized extreme value and Pearson type III;Then,the co-occurrence return periods and the design rainstorm values were calculated;Finally,the risk probabilities of exceed successive three-day or seven-day rainstorm amounts were calculated based on conditional distribution.