An Improved Copula Method For Analysis Of Influencing Factors Of Runoff In Alpine Region

In the analysis of multivariate correlation,Copula method and pair-copula models gradually become important tools in the analysis of multivariate correlation.Using cop-ula to construct the joint distribution of hydrological variables has become a common method in the application of hydrological statistics.We introduce copula and pair-copula models,and apply these tools in the anal-ysis of the the runoff character and its affecters in plateau climatic conditions or in high alpine region,building pair-copula models.Based on the ATD index proposed by-Xiong et.al,the former researchers always calculate ATD series by linear correlation coefficient,and build generalized linear models.Based on the previous method,this paper adds the method of calculating the ATD sequence by copula method,and adds the pair-copula model of runoff,precipitation and ATD sequence,and then obtains a more comprehensive improvement model applying to the upper reaches of the Yangtze River Batang basin.The results show that the validity of the copula method and the superiority of the Pair-copula method in this region are illustrated by the feasibility of the cumulative temperature difference ATD sequence in this region,and then the comprehensive model Practicality.At the same time,through the results of each model fitting,the water flow characteristics and influencing factors of the annual runoff series in some alpine region are shown to some extent.