Gis-based Flood Risk Assessment In The Dongting Lake Region, Hunan, Central China

Flood, the most common natural hazards in the world, caused serious loss to life and destruction of building and infrastructure. Flood hazards have occurred frequently in China. Hence, the flood research is very meaningful for theory and reality, of which the flood risk assessment is an important content for the flood hazard mitigation. The focus of this study is the Dongting Lake region. On the base of remote sensing data, ground meteorological data, rainfall data, social and economic data, using spatial multi-criteria analysis (SMCA) techniques in GIS combination fuzzy analytic hierarchy process (FAHP) weighting approach, flood risk assessment model was built to analysis the distribution of flood risk in the Dongting Lake region. Some conclusions were obtained as follows:(1) On the base of the regional flood disaster theory, integrating some principle and method, evaluation indicator system of flood risk was developed in this paper. Hence, ten indicators were selected, including elevation, vegetation cover, drainage network, precipitation, passing flood, water conservancy project, population, production, cropland and transportation.(2)Considering practical situation of the study area, combining spatial multi-criteria analysis and fuzzy analytic hierarchy process, flood risk assessment model was built. The flood risk index map was generated by multiplying the two composite index maps for hazard and vulnerability. The intermediate map of hazards was constructed again by overlay the six other intermediate weighted maps using addition in ArcGIS9.2 software environment. The intermediate map of Vulnerability was generated by combining the four vulnerability indicator maps.(3) Finally, the assessment results of flood hazard, flood vulnerability and flood risk were analyzed, respectively. The high hazard zone in the study area is mainly distributed in the center of Dongting Lake region, while the high vulnerability zone is distributed in the northwest and southeast. In this study, five categories of flood risk were distinguished: very low, low, medium, high and very high. 14.62% of the study area was found to be very low risk. Low, medium and high risk zones made up 21.37%, 20.59% and 32.47%, respectively. The very high risk area constituted 10.95% of the total study area. The high risk zone is mainly distributed in the northern and central plains. Nanxian County, Anxiang County, Huarong County, Changde City, Yueyang City, Jinshi County, Lianxian County, Miluo County, Yuanjing County and Changsha City were found in high risk zones. It primarily caused by the very high hazard values of the hazard indicators such as topography, drainage network highly susceptible to flood combined with high vulnerability values. Highly elevated land in the study area is mainly distributed in western, southwest and southern marginal hills representing the low risk zones. It primarily caused by the low hazard values and the low vulnerability values. The results were proved to be corresponding with the reality and have practical application.