Research On Design Flood Combination Of Sluices Based On Copula Function

The sluice constructed at the inflow-mouth of the branches is suffered from the flood of the main stream and the tributary simultaneously.At present,there is no mature method to determine the quantitative relationship between the design flood combination and the frequency of occurrence of the flood of the main stream and the tributary of this kind of sluices.The design flood combination of sluices is adopted according to the experience frequently.This paper attends to apply Copula function into the design flood combination in the view of the existing problems and uses the Guiping shipping hub as the example to discuss.On the basis of the theory of the structure of Copula function,parameter estimation and selection,this paper constructs four kinds of commonly used Archimedean Copula joint distribution function using the flood data of Guiping shipping hub and estimates the goodness of fit to choose the Copula function type which is the most suitable for the flood combination problems of sluices of Guiping shipping hub.Then it discusses the method to determine the design flood combination of sluices of Guiping shipping hub based on Copula function.The main achievements are as follows.(1)The design recurrence interval of sluices should be the co-occurrence recurrence interval.Making the flood calculation for all the flood combinations of which the co-occurrence recurrence interval equals to the recurrence interval and designing according to the flood combination with highest flood discharge water level,thus can ensure the flood discharge meet the design requirement.(2)The flood discharge water level of Guiping shipping hub is mainly affected by the main stream flood of Xijiang River,and the effect of the flood of Yujiang River is smaller.Among all the flood combinations that the co-occurrence recurrence interval is 100 years,the greater the flood of the main stream,the higher the flood discharge water level.(3)To make the flood calculation for all the flood combinations that the co-occurrence recurrence interval is 100 years and it turns out that the design flood level of Guiping shipping hub is 43.26m and the original design flood level of the based on the empirical method is 0.22m higher than it.The original design flood level can meet the demand of the flood control but is of partial safety.The research results of this paper show that the Copula function theoretical system which contains establishment,evaluation and optimization of the function model can effectively solve the problems about how to determine the design flood combination of sluices.These achievements provide the feasible method of theory for the determination of the design flood combination of sluices,and can effectively promote the perfection of sluice desigh theory,security construction and management in our country.