Risk Assessment Of Typhoon Disasters In China Coastal Area

In the context of global warming and sea level rise, the frequency and intensity of typhoon wind,rain and storm surge have enhanced, the losses of typhoon disasters have increased in China coastal areas, which seriously threaten the sustainable development of human society. Therefore, how to do typhoon disasters risk management and reduce the losses of typhoon disasters have been the priority subject.Under the support of the National Natural Science Foundation project "Coastal Cities Natural Disasters Emergency Plan Scenario Analysis"(NO.40730526), on the basis of the achievements of previous development in disaster risk research, the study constructed the theories of typhoon disaster system and proposed the theoretical framework and method system of typhoon disaster risk assessment. Considering the characteristic of typhoon disaster system and study region, the index system and correction of risk curves methods were used for typhoon disaster comprehensive risk assessment in China coastal areas and typhoon storm surge disaster dynamic risk assessment in typical coastal city(Shanghai) respectively. The results aimed to provide the theoretical basis and scientific support for the government policy-making. The main works and conclusions of this research are as follows:(1) This research proposes the theoretical and method system of typhoon disaster system risk assessment. The typhoon disaster system theories are constructed. The dynamic typhoon disaster clain system are formed under the background of global warming and fast urbanization and composed of typhoon wind clain, typhoon rain clain and typhoon storm surge clain. On the base, The typhoon disaster system risk assessment framework is put forward, mainly including risk identification, risk analysis and risk evaluation. At last, on the base of summarizing disaster risk assessment methods,the research proposes the assessment flows and methods of typhoon disaster comprehensive risk and typhoon storm surge disaster dynamic risk.(2) The typhoon disaster comprehensive risk was identified from the survey of nature, society, economy and the feature of landed typhoon. The index systems were built up respectively from four aspects of hazard factors, historic disasters, exposure&fragibility and prevention&mitigation ability. The index values were calculated and the spatial distribution characteristics of the indexs were analyzed. Then, the analytic hierarchy process(AHP)was used to determine the index weight. According to comprehensive risk assessment model, the typhoon disaster risk index values were also calculated and the calculation results were analyzed and evaluated. The results showed that2%of China coastal areas belong to the highest risk level and locate in shanwei and shantou cities of Guangdong province;18%of China coastal areas belong to a higher level of risk and mainly distribute in Hainan province and the coastal areas of Guangdong, Fujian and Zhejiang provinces where the occurrence frequency and intensity of typhoon disasters are big and the people and economy are dense;26%of China coastal areas belong to a middle level of risk and mainly distribute in the coastal cities of Guangxi province, Shanghai city, the near cities of Yangtze River Delta and the inner areas of Guangdong, Fujian and Zhejiang provinces;54%of China coastal areas belong to the lowest and lower levels of risk, mainly distribute in Hebei province, Liaoning province, Beijing city, Tianjin city and the most parts of Guangxi and Shandong province. In macroscopic view, the risk of typhoon disasters is the highest in Guangdong province, the risk of typhoon disasters is higher in Hainan, Fujian and Zhejiang provinces.(3) The research selected Shanghai as the typical study area, selected typhoon storm surge as a typical disaster to carry out the dynamic risk assessment. Based on the dynamic and slow effect of sea level rise on typhoon storm surge and the space differences of the seawall destruction, the research chose a site of Pudong as a typical study case, used risk curve fitting and correction methods to analyze and evaluate the typhoon storm surge scenario disaster risk, in the context of sea level rise scenario. The results showed that the typhoon storm surge disaster risk present the changing trend of log function. When the values of sea level rise are Om and0.5m, The risk values of typhoon storm surge disaster are about0.0045billion yuan and6.2497billion yuan in turn, belonging to the acceptable risk. When the values of sea level rise is1.0m, The risk value is51503.7489billion yuan, belonging to the unacceptable risk. The influence of sea level rise on typhoon storm surge disaster risk will be great.