Research On The Risk Of Rainstorm And Flood Disaster Under The Complex Terrain Of Guizhou Mountains

Guizhou is an area where rainstorm and flood disasters occurs frequently,which are mainly caused by the unusually high and heavy precipitation and the accumulation effect of the special topography of Guizhou.In recent years,with the continuous intensification of extreme weather and climate events,the degree of local rainstorm disasters in Guizhou has been increasing year by year.As a basic research work,rainstorm disaster risk assessment has been paid more and more attention by the government and the public.The scientific assessment of rainstorm disaster risk in Guizhou is of great significance for the government to make scientific decisions on rainstorm disaster prevention and the public to avoid disasters scientifically.Based on the daily precipitation data from 84 meteorological stations in Guizhou province from 1991 to 2020,social and economic data,population data and remote sensing vegetation data,spatial and temporal change of precipitation and rainstorm disaster risk were analyzed.A comprehensive risk assessment model for rainstorm disasters in Guizhou Province was constructed from four aspects that are the risk of disaster factors,the sensitivity of disaster-producing environment,the vulnerability to disaster,and the ability to prevent and reduce disasters by using the rainstorm disaster risk theory.The results are as follows:(1)The distribution of annual precipitation was uneven in Guizhou province from 1991 to 2020,with more precipitation distributed in an east-southwest direction.The precipitation with high-value occurred in the eastern edge and southern part of Guizhou Province.The precipitation showed a decreasing trend but in the increasing phase in the last 10 years.However,the changes in the annual heavy rainfall and the number of days with heavy rain in Guizhou province show an increasing trend,indicating that the possibility of extreme precipitation with heavy rain is gradually increasing in the past 30 years although the total precipitation shows decreasing trend.The spatial distribution characteristics of daily heavy rainfall,daily maximum precipitation and the number of heavy rain days in Guizhou Province are generally consistent with high-value of precipitation concentrating in the northeastern and southern parts of the province.(2)In the past 30 years,the second highest and highest risk of disaster caused by rainstorm in Guizhou province is mainly distributed in Zunyi,western and northern Qiannan,southeastern Anshun,eastern and northern Qianxinan,northern Liupanshui and eastern Qiandongnan.The second highest risk of disaster occurs in Renhuai,Tongzi,Fenggang,Meitan,Wangmo,Weng’an and other areas.The areas with the high rainstorm risk are the key areas for rainstorm and flood prevention including Chishui,Suiyang,Qingzhen,Huishui,Changshun,Ziyun,Pu’an,Shuicheng and Jin Ping.In the past 30 years,the second-highest rainstorm risk level of disaster in Guizhou province changed mainly in Zunyi,Qiannan,Guiyang,Liupanshui and other areas.There is an increasing trend in the risk of heavy rain in Shuicheng,Tongren,and the eastern part of Qiandongnan.Other areas in Guizhou province are basically at a lower-low risk level of heavy rain.(3)There are many rivers,complex terrain,wrinkle hills,and good ecological environment in Guizhou province where the sensitivity of disaster environment is mostly above the intermediate level.The areas with high sensitivity to disaster environment are mainly located around the Nanpanjiang River system which is in the southern part of Guizhou province.The sub-highly sensitive areas are mainly distributed in the Wujiang River system which is in the central and northern parts of the province and the Yuanjiang River system and the Liujiang River system which are in the east part of the province.The moderately sensitive areas are mainly concentrated in the southeastern part of the province with better vegetation and around the Chishui River water system in the north and the Beipan River water system in the south.(4)The areas with the highest disaster-bearing body and the second highest vulnerability in Guizhou are mainly concentrated in the main urban area of Guiyang,the main urban area of Zunyi,the main urban area of Bijie,the main urban area of Qianxinan,Renhuai and Panzhou.The medium-vulnerability areas are mainly distributed in the economically developed areas and high-density areas of other cities and states.The areas with the highest and second highest disaster resilience in Guizhou are mainly concentrated in the main urban area of Guiyang and Renhuai.The medium disaster-resistant areas in China are mainly concentrated in Zunyi,Anshun,Qianxinan,Qiannan,Qiandongnan,Tongren,the main urban area of Liupanshui and some economically developed cities and counties.(5)The areas with high and sub-high risk levels of rainstorm disasters in Guizhou are mainly located in Suiyang county,Meitan county,Renhuai,Chishui,Qingzhen,Guiyang,Changshun county and Huishui county in Qiannan,Shuicheng county,Liupanshui,and Zunyi City.Ziyun county,Pu’an county and Wangmo county in Qianxinan and Jinping county in Qiandongnan.The medium-risk areas are mainly concentrated in Zunyi and most areas of Liupanshui,Guiyang,southern parts of Qianxinan and Anshun,and eastern part of Tongren and Qiandongnan.