| Rainstorm disaster is one of the major natural disasters in China,which brings serious damage to our economic and social development.In recent decades,under the background of global climate change,the frequency of extreme weather events in our country has greatly increased,in addition,the process of urbanization has accelerated,the population and economy are highly concentrated.Once a meteorological disaster occurs,the consequences are extremely serious and will inevitably bring serious obstacles to the sustainable development of the regional social economy.The climate in Chongqing belongs to a humid subtropical monsoon humid climate,In the summer,affected by the southeast monsoon and the southwest monsoon,rainfall is abundant and rainstorms frequently occur;The geological structure in Chongqing are very complex and the landform types are various,under the special geographical conditions and natural conditions,regional storms often cause flood disasters,geological disasters,and environmental pollution,which cause serious damage to the healthy development of the economy.Therefore,it is of great practical significance to carry out quantitative evaluation research on regional rainstorm and rainstorm disaster in Chongqing,which is of great practical significance to scientifically carrying out disaster prevention and reduction work.The study was based on precipitation data of 34 national meteorological stations in Chongqing from 1962 to 2016 and regional rainstorm disasters from 1997 to 2016 recorded in documents such as "Meteorological Disasters",the following work were carried out: Firstly,based on the daily precipitation data of 34 national meteorological stations in Chongqing,the Perniciousness of regional rainstorm from 1962~2016 were studied by probability statistics,Morlet wavelet analysis and ArcGIS spatial analysis;Then the disaster mechanism of regional rainstorm in Chongqing were analyzed and investigated the natural disasters caused by regional rainstorms and their disaster chains;Finally,a comprehensive assessment model of regional rainstorm disasters inChongqing was constructed based on the entropy weight model,The 31 regional rainstorm disasters selected from 1997 to 2016 were comprehensively assessed and graded.The main conclusions are as follows:(1)The regional rainstorm Perniciousness in Chongqing are severe.Indexes including average rainfall volume of regional rainstorm,24h-rainfall extreme values,the coverage and the duration of regional rainstorm were selected to establish a regional storm risk assessment model to evaluate the regional rainstorm risk in Chongqing,combined with the classification of percentiles;among the 176 regional rainstorms,mild risk occurred 83 times,accounting for 47.16%;moderate risk occurred 49 times,accounting for 27.84%;severe risk occurred 35 times,accounting for 19.89%;extremely severe risk occurred 9 times,accounting for 5.11%.(2)There are significant intra-annual,inter-annual and inter-decadal variations of regional rainstorm risk in Chongqing.It is in June and July that the regional heavy rainstorms occur in Chongqing strongly,during which the average regional rainstorm risk index is the highest in July,and the other months are relatively low.;there are 7a and 28 a variation periods in the regional rainstorm in Chongqing;there were small differences in the number and severity of regional rainstorm in different periods,but the grade composition of regional rainstorm were quite different.(3)The regional disparity of regional heavy rainstorms in Chongqing is significantly different.Kaizhou(the city in the northeast of Chongqing)and Rongchang(the city in the west of Chongqing)were regional rainstorm centers in Chongqing;furthermore,the regional rainstorm centers also has obvious difference in each season,in spring,the regional rainstorm center was mainly occurred in the western of Chongqing,in summer,the regional rainstorm center was mainly occurred in the northeast and western of Chongqing,while in autumn,the regional rainstorm center was mainly occurred in the northeast of Chongqing.(4)Regional rainstorm in Chongqing stimulate a variety of natural disasters and constituted disaster chains.The disasters caused by regional rainstorm in Chongqing mainly include floods,soil erosion,landslides,collapses,mudslides,damming lakes,environmental pollution,and diseases.And the possible disaster chains can be summed up as follows:(1)rainstorms-floods-water and soil loss disaster chain;(2)rainstorms-collapse or landslide-debris flow disaster chain;(3)rainstorms-collapse or landslide-barrier lake-chain of mountain torrents;(4)rainstorms-flood-environmental pollution-disease disaster chain.Regional rainstorm disasters were mainly affected by specialgeological and geomorphologic environment,hydrology,weather and other natural factors,however,unreasonable human activities aggravated the severity of regional rainstorm disasters.(5)The regional rainstorm disasters are serious in Chongqing.Indexes including affected populations,areas affected by crops and direct economic losses were selected to establish a quantitative assessment model for regional rainstorm disasters in Chongqing based on the entropy model,and the comprehensive disaster index for 31 regional rainstorms from 1997 to 2016 were calculated.Among these 31 regional storms,minor disaster occurred 16 times,accounting for 51.61%;moderate disaster occurred 8times,accounting for 25.81%;mass disaster occurred 4 times,accounting for 12.90%;severe disaster occurred 3 times,accounting for 9.68%.(6)The regional rainstorm risk index of Chongqing is closely related to the comprehensive disaster index of regional rainstorm,and the correlation coefficient between them is as high as 0.7.However,it cannot simply be said that the higher the risk of regional storms is,the more serious the damage will be.the severity of the disaster is affected not only by the risk of the hazards,but also by the level of local economic development and the overall ability to prevent and mitigate disasters. |
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