Temporal And Spatial Distribution Of Rainstorm And Risk Assessment Of Rainstorm And Flood Disaster In Kaifeng City

In recent years,under the background of increasing global climate change,extreme precipitation events occur frequently,which leads more serious floods.At the same time,with the acceleration of urbanization,the losses caused by rainstorms and floods are also increasing year by year.The disaster has become one of the main meteorological catastrophes affecting the sustainable and healthy development of urban society and economy in our country.As a key area of flood control and disaster reduction in Henan Province,it would make great actual sense to study and assess the temporal and spatial distribution of rainstorms and the risk of rainstorm and flood disasters in Kaifeng City,which is of great practical significance for the development of flood control and disaster reduction work in Kaifeng and the protection of the safety of local people’s lives and properties.Based on the daily precipitation data from 1957 to 2020 at five conventional meteorological stations in Kaifeng,the article analyzed the spatial and temporal analysis of rainstorm in Kaifeng from trend analysis,mutation test,cycle variation and other temporal and spatial scales using Python,MATLAB and Arc GIS,and obtained the temporal variation trend,Mann-Kendall mutation test results,Morlet wavelet analysis results and spatial distribution of rainstorm in Kaifeng.Fourteen evaluation indicators are selected from four levels: the risk of disaster-causing factors,the sensitivity of the disaster-pregnant environment,the vulnerability of the disaster-bearing body,and the ability of disaster prevention and mitigation.The matrixes for fuzzy and weight were determined by the analysis method and degree of membership function,respectively,and formed a multi-level fuzzy comprehensive evaluation model eventually.With the help of Arc GIS for desktop,the results of the fuzzy comprehensive evaluation of the risk of rainstorm and flood disaster in Kaifeng were depicted in spatial scale.Finally,in view of the rainstorm and flood disaster in Kaifeng,this paper puts forward corresponding risk management measures from four levels the above mentioned to provide reference for rainstorm and flood disasters’ risk prevention and control.The main research results are as follows:(1)Spatial and temporal distribution characteristics of precipitation in Kaifeng.On the time scale,the multi-year average precipitation in Kaifeng is 653 mm,and the annual precipitation is fluctuating and decreasing,with the maximum annual precipitation of 1030 mm in 1964;most of the annual precipitation distance percentages are at the climatic average,and the overall trend is stable with decreasing;the sudden change of annual precipitation occurs several times before 1990,and the sudden change occurs from 2001 to2003.The main period of the annual precipitation series is 6 years.The maximum daily maximum precipitation in Kaifeng is 217.8 mm in 64 years,which occurred in 1992;the abrupt changes in daily maximum precipitation mainly occurred between 1980 and 1994;the longest quasi-period of daily maximum precipitation series is 25 years,and the main period is 7 years.From the spatial scale,the distribution of annual average precipitation across Kaifeng mainly shows more in the east and southwest and less in the northwest;the daily maximum precipitation shows more in the northwest and southeast and less in the northeast and southwest.(2)Spatial and temporal distribution characteristics of rainstorms in Kaifeng.The first main cycle of the average rainstorm volume series is 7 years;the first main cycle of the rainstorm day series is 5 years,and the second main cycle is 8 years,and the current period is in the period of heavy rainstorms of 8 years.Heavy rainfall in Kaifeng only occurs from March to October and is mainly concentrated in summer.From the spatial scale,the average rainstorm amount in Kaifeng city shows the characteristics of more in the east and less in the middle and west;the annual average number of rainstorm days shows the pattern of decreasing from southeast to northwest in order.(3)Analysis of risk assessment factors of rainstorm and flood disaster in Kaifeng City.In terms of the risk of disaster-causing factors,the high-risk areas are mainly concentrated in the northwestern and eastern areas of Kaifeng City,that is,downtown Kaifeng and Qixian County.In terms of sensitivity of disaster-inducing environment,there is no obvious geographical difference in sensitivity level,and the overall sensitivity is high.In terms of disaster-bearing body susceptibility,Gulou District and Shunhe Huizi District are highly susceptible areas.In terms of disaster prevention and mitigation capacity,only Gulou District is a high disaster prevention and mitigation capacity zone.(4)Comprehensive assessment of the risk of rainstorm and flood disaster in Kaifeng City.The areas with higher comprehensive risk levels of rainstorm and flood disasters in Kaifeng are mainly concentrated in the northwest and east of Kaifeng,namely Longting District,Gulou District,Yuwangtai District,Shunhe Hui District and Qixian County.The maximum daily precipitation and the average torrential rainfall are both high and dangerous,and because they are basically in the medium-high vulnerable area,the degree of vulnerability is high.Therefore,in the season of frequent rainstorms,it is necessary to pay attention to the disaster warning and prevention work in these areas.