Temporal And Spatial Distribution Of Rainstorm And Probability Analysis Of Recurrence Period In Liaoning Province

As a severe disastrous weather,rainstorm brings serious harm to the national economy and People's life and property safety.In the face of the current situation of complex disaster,weak prevention and mitigation measures,the monitoring and early warning of natural disasters,post-disaster reconstruction work has been more and more attention by the State and society.The rainstorm disaster often has the bad influence to our country people's productive life,according to the national each policy guideline,the rainstorm event related research becomes one of the geographical circles attention important.Therefore,it is beneficial to control and slow down the urban waterlogging,and to provide scientific and rational guidance for the prevention of rainstorm in the area,and to help the relevant government departments to formulate disaster prevention and mitigation policies.In recent years,Liaoning Province has been greatly affected by rainstorm,resulting in increasing social and economic losses.The basic data of the study include 1957-2015 daily precipitation data,DEM elevation data,climatic and dry zone data and agricultural disaster data,The temporal and spatial characteristics of various rainstorm elements(rainstorm volume,rainstorm days,rainstorm intensity and rainstorm contribution rate)in Liaoning Province are analyzed,Based on different topography and dry wet zoning,this paper analyzes the combination probability and recurrence period of multiple rainstorm elements,and analyzes the data of agricultural disaster damage.The research shows that:(1)Rainstorm volume,rainstorm intensity and rainstorm contribution rate decreased slowly in 1957-2015,and the rainstorm days showed a significant downward trend during the 1960-1980 years,while other periods were roughly the same as those in the same period;All the elements of the rainstorm have abrupt points during the study period,The main oscillation period of the four elements of the rainstorm was about 40 years.The peak value of the wavelet variance appeared in about 40 years and passed the reliability test of 0.05.(2)In 1957-2015,the high value area of the four rainstorm elements was distributed in the southwest of Chaoyang,the west of Huludao and most parts of Benxi,Dandong and Anshan.The highest annual rainstorm occurred in Dandong Station(368.4mm),and the rainstorm and rainstorm days were located in the middle area of Liaoning Province,The low value area of rainstorm intensity is north of Chaoyang and western area of Fuxin,the area of low value area of rainstorm contribution rate is relatively wide,and the contribution rate of rainstorm is low in most areas of northern Liaoning province.(3)The marginal distribution of rainstorm in Chaoyang and Fuxin is EV distribution,the number of rainstorm days is suitable for Poisson distribution,and the marginal distribution of rainstorm contribution rate in Chaoyang and Fuxin are respectively exp distribution and EV distribution;Zhangwu and Yingkou's rainstorm elements(rainstorm volume,rainstorm intensity,rainstorm contribution rate),the marginal distribution and the GEV distribution were fitted well.The edge distribution of the selected rainstorm elements(rainstorm volume and rainstorm intensity)in the party,Dandong and Dalian also accords with the GEV distribution,and the edge distribution of the rainstorm days in the party and Dalian accords with the Poisson distribution,and the edge distribution of the rainstorm days in Dandong accords with the GAM distribution.(4)The optimal joint function of Chaoyang,Yingkou and Dandong is Frank Copula function,and the joint function of Fuxin,Zhangwu,Zhangdang and Dalian is more excellent Clayton Copula function.With the increase of the Copula value,the combined characteristics of rainstorm are more significant,and the main influence of different representative sites on the comprehensive characteristics of rainstorm is different.(5)The combination of multiple factors of rainstorm is less than the recurrence period of single factor,the degree of accuracy of the joint recurrence period is higher,which is consistent with the actual situation.During the period of 5,10,20,and 50 years,the occurrence probability takes on a variation of "The central region is higher,while the eastern and western regions are lower ".So we need to pay special attention to the low value of the region in the future rainstorm disaster prevention and mitigation work,such as southern Chaoyang City,southern Huludao City,Anshan City,Dandong City and other places;The combined analysis of damage data shows that the severity of agricultural production in the province under the influence of rainstorm events can be divided into 5 levels,Fuxin City,Shenyang City,Tieling City are the lowest grade I,Dalian City,Jinzhou City,Panjin City,Liaoyang City are II,Huludao City,Fushun City are III,Chaoyang City,Yingkou City,Anshan City,Benxi City are IV,Dandong City is the most senior level V.