Study On Formation Mechanism And Lability Zoning Of Geological Hazards In Yanzi River Basin Of Longnan

The Yanzi River Basin is located in Longnan County,Gansu Province.Geological hazards in the area is the density distribution,high degree of development,one of the most serious areas of harm in Gansu Province.The types of geological hazards in the area mainly are landslide,collapse and debris flow,with sudden,mass and repetitive characteristics.Frequent geological hazards pose a great threat to human life and property.Research results can provide the swallow river geological hazards and disaster prevention and mitigation,town planning,and provide the fundamental basis of land use by conducting the formation mechanisms of geological hazards and geological hazards in the area prone districts research.It is of great significance to the study of geological hazards and economic development in the area.This paper took the geological disaster of the Yanzi River Basin as the research object based on the China Geological Survey project "Jialing River upstream Yanzi River Basin geological disaster investigation".Systematically carried out the Yanzi River Basin geological environment background,disaster investigation,geological disaster formation conditions,formation mechanism and easy to zoning and other research work.The main types and development characteristics of geological hazards in the area were determined,and the development characteristics and distribution of landslide,collapse and debris flow were analyzed.The results showed that the topography,stratigraphic and rock mass structure,geological structure,slope structure and hydrogeological characteristics were the internal conditions of geological hazards,rainfall,earthquakes,vegetation and human engineering activities were external predisposing factors for geological hazards.The occurrence of geological hazards in the region was the result of the combined effect both internal cause and external cause.The study also revealed the formation mechanism of "accumulation — rock" landslide,fractured — falling,bending — dumping — slipping,fragmentation — slip type three types of collapse and valley — type debris flow in Yanzi River Basin.Based on the above research,the GIS—based information model was used to study the high—precision susceptibility zoning of the Yanzi River Basin and the key investigation area,it divided the susceptibility degree of geological hazard in the Yanzi River Basin into high,medium,low and very low four zones.The high—prone area accounted for 9.25% of the basin area,concentrated in the main branch of the swallow river,important tributaries along the frequent human engineering activities of the valley,the main road along the slope;the prone area accounted for 26.14% of the basin area,low prone area and very low prone area accounted for 64.61% of the basin area.Monitoring,early warning and disaster mitigation measures should be strengthened in the high prone areas.