Risk zoning of flood disaster based on GIS: A case study of Xiangjiang River, Hunan Province, China

The risk zoning of flood disaster is an important content of risk evaluation and management. It provides science basis for the risk management and environmental policy-making. The risk assessment index system was built by using the method of risk assessment of natural disasters and geographic information system (GIS). The system contains the integrated risk probability (P
_i
) and the comprehensive socioeconomic vulnerability (S
_i
) of flood disaster from two aspects of 9 influence factors and applies to the Hunan section of Xiangjiang River. With the support of ArcGIS, maps of every indexes of flood risk were outlined. Then the regionalization of comprehensive risk of flood disaster (R
_i
) was also drawn by overlaying the maps gotten from addition method. The results show that, the highest value of P
_i
is distributed in Xiangyin and along the lower reaches of Xiangjiang River, Qidong, Dongan and the areas of high altitude are the lowest; the highest value of S
_i
is distributed in Chang-Zhu-Tan region, and the lower is in Lingling, Dongan and Wangcheng; the highest value of R
_i
is distributed in Xiangyin and Chang-Zhu-Tan area, the lower is in Hengyang City, and the lowest is in Lingling and Dongan. The result is identical with the actual situation of the study area.