| Typhoons,as high-frequency and high-destructive natural disasters,bring huge damage and losses to coastal countries and regions every year.China is on the verge of the northwestern Pacific Ocean,the main source of typhoons in the world,so it has become one of the worst-affected countries by typhoons.In the context of global climate instability and rapid urbanization,the intensity and frequency of typhoons and the various disasters they cause,such as strong winds,heavy rain and storm surges,have increased,which seriously threatens the health and safety of people’s lives and property and the sustainable development of society in our country.Conduct a specific analysis of the causes of typhoon disaster risks to help cities discover the inadequacies of existing typhoon disaster prevention measures,it provides a certain basis for the formulation of typhoon disaster prevention and mitigation policies,and then can reduce the losses caused by typhoon disasters,which is of great significance in typhoon disaster prevention.Based on the analysis of existing research,this paper conducts the following research:(1)Obtain the historical Northwest Pacific typhoon track data,and perform exponential smoothing on the western Pacific typhoon data and the landing Chinese typhoon data,respectively.The interannual variation characteristics of typhoons landing in China and the distribution characteristics of landing sites were analyzed,and the characteristics of typhoon disasters in China were analyzed and studied.(2)Based on the historical data from 2000 to 2018,a typhoon and social and humanistic database of coastal cities in China from 2000 to 2018 was established.Selecting evaluation index factors by studying and consulting literature,from the perspective of the disaster-pregnant environment of typhoon disasters in the study area,comprehensively considering the factors of typhoon disasters themselves,social factors,natural factors,etc.An evaluation model with typhoon-causing factors,social disaster prevention and mitigation factors and natural disaster-bearing factors as subsystems is established.In terms of typhoon disaster-causing factors,the frequency and intensity of typhoons are selected as secondary index factors,and the factor data are assigned statistics according to the degree of typhoon landing and impact.In terms of social disaster prevention and mitigation factors,per capita urban roads and regional GDP are selected to represent the level of social development,and population density,primary industry share of GDP,total passenger and freight volume,and factors such as water conservancy management and the number of employees in similar industries,the number of hospital beds,and the number of hospital health workers that can be degraded in a timely manner after the disaster are used as secondary evaluation indicators.The secondary indicators such as the average terrain elevation,the green coverage rate of the built-up area and the area of garden green space are selected as natural disaster-bearing factors.(3)Using dispersion standardization and AHP analytic hierarchy process,using GIS technology,and using evaluation model,the disaster risk assessment and disaster grade analysis were carried out on the major coastal cities in China that suffered severe typhoon disasters.The typhoon disaster risk zoning map is analyzed in detail,and the typhoon disaster risk of each coastal province and city is obtained.According to the results of the typhoon risk level of the three subsystems,the advantages and disadvantages of the typhoon disaster-pregnancy environment in each region are analyzed,discuss the insufficiency of typhoon disaster prevention and mitigation measures,so as to provide an effective basis for the next step to formulate disaster mitigation measures.The following research results were obtained from the above research:(1)The temporal and spatial distribution characteristics of landfall typhoons in China from 2000 to 2018 are studied.It is found that the inter-annual variation generally shows an increasing trend,and has a relatively obvious oscillation period,which is 3-4years,which is basically consistent with the changing trend of the number of typhoons in the western Pacific.In terms of monthly variation,the number of typhoon landfalls varies significantly from season to season,with typhoon disasters mainly occurring in summer and autumn.In terms of geographical distribution characteristics,the frequency of typhoon landfall numbers generally decreases from south to north and from coastal areas to inland areas.Guangdong,Fujian,Guangxi,Taiwan and other coastal provinces have frequent landfall typhoons.From 2000 to 2018,a total of 64 typhoons landed in Guangdong Province,accounting for 19.8% of the national total.Among the coastal cities,most of the typhoon-affected cities are located in Guangdong and Fujian provinces,and it is necessary to focus on strengthening typhoon disaster prevention work.(2)The weights of the indicators are determined by the analytic hierarchy process,and the research area can be graded by standardizing the comprehensive data after the typhoon factor indicators are weighted,and the risk assessment of typhoon disasters in coastal cities is carried out.The results show that there are obvious regional differences in the comprehensive risk of typhoon disasters in coastal cities,showing a decreasing trend from south to north.In terms of typhoon disasters themselves,Zhanjiang,Yangjiang,Maoming,Jiangmen,Fuzhou,Zhangzhou and other cities are most frequently affected by typhoons.Among them,Zhanjiang is the most affected by typhoons.The number of landfall typhoons from 2000 to 2018 reached 19,and the average annual intensity of typhoons is also the highest in the study area,reaching a level of 6.46.Qingdao,Yantai,Weihai,Rizhao,Linyi and other cities were less affected by typhoon disasters.In the past 19 years,the number of typhoons affected was less than 20,and the average annual intensity of typhoons was below level 2.In the risk analysis of social disaster prevention and mitigation factors,the risk differences between cities in the study area are not obvious,and most typhoons are in the medium and low risk areas.Cities in both medium-risk and low-risk areas accounted for 41% of all cities studied,15% of prefecture-level cities were in high-risk areas for this factor,and another 3% were in very-high-risk areas.Hangzhou is the city with the lowest typhoon risk in social disaster prevention and mitigation,while Shantou has the highest risk.It is necessary to focus on improving the construction of typhoon disaster prevention projects,improving the level of urban greening,and formulating typhoon disaster prevention and mitigation measures.In the evaluation of the natural disasterbearing subsystem,the terrain elevation weight coefficient is relatively large,so the evaluation results have continuity in the spatial distribution.(3)The corresponding risk score results were obtained by comprehensive risk in GIS.In general,there are obvious regional differences in the comprehensive risk of typhoon disasters,showing a decreasing trend from south to north.Analyzed by province,cities in the low-risk area are all located in Shandong Province,cities in Jiangsu Province,Shanghai,and southern Zhejiang Province are at medium risk,cities in the extremely high-risk area are located in Fujian Province and southern Guangdong Province,and the remaining cities are high-risk areas.Guangdong and Fujian,as the hardest hit areas of typhoon disaster risk,need to focus on strengthening typhoon disaster prevention work in coastal cities. |
