Risk assessment of geological disasters in Beichuan County after the Wenchuan earthquake based on ArcGIS

Extreme geological disasters have been occurring with increasing frequency, especially in Southwest China, seriously affecting people’s lives and production. It is necessary and urgent to quickly assess the risk level of geological disasters and formulate reasonable emergency measures. In this paper, we take Beichuan Qiang Autonomous County (hereinafter referred to as Beichuan County) after the Wenchuan earthquake as an example, use ArcGIS software and SPSS software to determine the optimal geological disaster evaluation factors, and apply the frequency ratio model method ( FR ) to evaluate the susceptibility risk of the study area. Geological hazard risk assessment ( R ) combines the hazard assessment ( H ) and the vulnerability assessment of the hazard-bearing body ( V ), namely, R = H × V . The hazard assessment is based on the vulnerability assessment zoning map, which is obtained by overlaying the danger level onto each village, thus producing a danger assessment zoning map. H is then combined with the vulnerability assessment zoning map of the bearing body, which is obtained via the fuzzy comprehensive evaluation method, and the final risk assessment result is achieved. The results show that the medium- and high-risk areas make up the vast majority of the study area. Qushan town, Yong’an town, and Xiaoba town are extremely high-risk areas with both high risk and high vulnerability and therefore need to be the focus of prevention and control measures. The results of this study can provide a scientific basis for geological disaster management, monitoring, forecasting, emergency disaster relief, and environmental protection; furthermore, they have a certain reference value for early warning of geological disaster risks.