The Variation Characteristics Of The Tropical Cyclone Disaster In Zhejiang Province And Its Assessment

Tropical cyclone is a general name for tropical storm, severe tropical storm, typhoon, violent typhoon and super typhoon. Tropical cyclone is one of the greatest natural disasters, with great destructive power and the feature of suddenly happening. Using data of disaster situation in Zhejiang from 1950 to 2009, the variation characteristics of the disasters situation caused by tropical cyclones were analyzed in this paper. After comprehensive considering the variation of triggering agent, disaster body, formative environment, prevention and reduction capacity, characterization factors of disaster situation and triggering agent were analyzed. On the basis, the assessment model of disaster situation for tropical cyclone has been builds up. The main conclusions of this paper are as follows:With global warming, the number of and the intensity of tropical cyclones which hit Zhejiang province are growing, which indicates the disastrous losses caused by tropical cyclones have obvious inter-decadal characteristics. As time goes on, the damage areas of farmland and the direct economic loss are increasing, however, the number of collapsed houses is decreasing. In the same year, the greater the tropical cyclones are when they hit the land, the more people will die. As time goes on, the number of casualty is decreasing.Direct economic loss caused by tropical cyclones increases progressively with the GDP growth.1988,1994 and 2005 were the catastrophe points of direct economic loss emerged, when the direct economic loss caused by tropical cyclones didn't increases progressively with the GDP growth. In 2005, the index of direct economic loss decreased, which demonstrated the impact of prevention and reduction capacity to disaster situation. It also indicated the index of direct economic loss could eliminate the influence caused by GDP and price index to direct economic loss. To landing tropical cyclone, strong wind, heavy rain and storm surges are the main causes of the direct economy loss and of damage areas of farmland. Besides, strong wind and storm surges are also main causes of collapsed houses. As to influencing tropical cyclone, strong wind and heavy rain are the main causes of the direct economy loss and of collapsed houses. And the major cause of damage areas of farmland is heavy rain.In this paper, PCA were used to extract principal components and lower the dimension of triggering agent. Using support vector machine approach and judging principal components as factors, the assessment of hazards caused by tropical cyclones was finished in this paper. Support vector machine could effectively history matching the index of direct economic loss and the number of collapsed buildings. The assessment result matches with the observations well, but the assessment result for damage area of farmland didn't works very well. Therefore, how to improve the assessment result for damage area of farmland is the research direction in the future...