The Risk Analysis Of Debris Flow Hazards In The Small Watershed Sclae

Longxi river is located in wenchuan earthquake disaster zone, The earthquake caused the large amount of geological disasters such as landslides, debris flows, collapses?Due to the torrential rain, added a lot of geological hazards, especially debris flows?Debris flows destroyed many of the transport infrastructure, and made the parts of the electric power and communication interrupt, Caused direct economic loss of hundreds of millions of dollars. Study Longxi river to do the following:(1)After the study of predecessors' research results, through the survey of river stream, This paper analyzed the distribution, scale and characteristics of the debris flows before and after the disaster. We found that Longxi river are mainly composed of medium and small-scale Debris flows, with the characteristics of Concealment, clusters, chain, destructive, type, etc.(2)On the basis of previous analysis results, this paper analyses the debris flows quantity, the change of the scale, and the correlation of factors such as stratum lithology, geological structure, The study area is divided into five levels, We found that the high risk areas are mainly concentrated in Bayi river, Jiangjia river, and so on,and most high dangerous watershed are focused on the upstream of debris flows.(3)Combining survey and aerial photo interpretation, on the basis of Hazard Bearing Body distribution such as land use present situation and the residential areas, etc. the Hazard Bearing Body of Longxi river exposure are analyzed, Found that exposure to the Hazard Bearing Body mainly drainage to the distribution,Minimum exposure area mainly for high altitude areas of woodlands and grasslands, Vulnerability of the highest is the study of population in the area and the most concentrated area of properties.(4)Combined with risk, exposure, vulnerability analysis, this paper completed the risk analysis in the study area. After considering the post-disaster development planning in the study area, the geological disaster prevention Suggestions were put forward in the study area, and the preliminary countermeasures. This study expects to post-earthquake recovery and reconstruction and protection of people's life and property security for reference, providing reliable basis for the comprehensive improvement in the study area planning data.