The Study Of Flood Disaster Risk Evaluation In Chongqing Based On GIS And Fuzzy Mathematics

Flood disaster is one of China's major natural disasters. Chongqing is located in the subtropical monsoon zone, and rainstorms occur frequently in summer by the the alternating effects of south-east monsoon and south-west monsoon. The terrain, on the whole, leans to the Yangtze river valley from the south and north. There are many rivers and reservoirs, while the impacting by of the pattern of the Sichuan Basin, forms an asymmetric centripetal waters based on the Yangtze Rive. All those make Chongqing an annual frequency of flood disaster up to 2～4 times, which forms a serious threat to the safe of people's lives and property. As a non-engineering measures, flood disaster risk assessment has an important significance to Chongqing's flood damage assessment, flood prevention, disaster relief, land use and development.This article discusses the basic principles and main content of the flood disaster risk assessment; presents the current and commonly used methods of flood disaster risk assessment and analyzes the advantages and disadvantages; introduces the basic theory of fuzzy mathematics and the basic steps of fuzzy comprehensive evaluation method, make the best of the advantages of fuzzy comprehensive evaluation method when evaluating the flood disaster risk. describes the basic features and the main functions of GIS and the application of GIS in flood disaster risk assessment. According to principles of flood risk assessment, the principle of indicator selection and evaluation methods, and the actual situation of the study areas, the paper selects the indicators of flood disaster risk assessment, and sets up indicators systems of flood disaster risk evaluation in Chongqing; based on fuzzy comprehensive evaluation method, constructes the model of fuzzy comprehensive evaluation to flood disaster risk in Chongqing; input the model to GIS, through processing, gets a map of the distribution of Chongqing's flood disaster risk.The map shows that the risk of flood disaster in Chongqing were significantly different:the high-risk areas are mainly distributed in the western, central and northeastern's Liangping County, Kaixian, and most of Wanzhou District; low-risk areas are mainly distributed in most parts of south-east and northeastern's Chengkou County, Wuxi County, Wushan County, Fengjie County and the eastern of Yunyang County. These are the results of combination of different natural environment and socio-economic factors in Chongqing.