Risk Assessment And Research Of Preventive Project Of The Debris Flow Of Da He In Lushan Country Of Ya’an City

The debris flow is a geological disaster of sudden outbreak and serious damages.With the growing economic and social activities, the overexploitation of natural resources and its sustained destruction to the environment have made the debris flow disaster become increasingly frequent and serious. Therefore, we must strengthen the efforts for the survey, research and control over the debris flow, and adopt the cost-effective disaster mitigation measures, thus preventing the occurrence of debris flow and minimizing disaster losses.The Dahe River, object of this study, is located in Lushan County, Ya’an City,Sichuan Province. There are no historical records of the outbreak of large-scale debris flow in this area. From our oniste visits, we find that there was the occurrence of small-scale high sand flood in 1962 and 1992 that inundated some roads and farmlands in the Pingxi Village in the downstream of the Dahe River, causing significant economic losses. Based on the characteristics of river basins and vallies in the Dahe River, we in this paper analyze the formation conditions and basic characteristics of debris flow and conduct the hazard assessment, on the basis of which the targeted prevention and treatment measures have been proposed. The research contents and achievements of this paper are shown as follows:1) Based on the geological and environmental conditions of debris flow in the Dahe River in the Lushan County, conduct the comprehensive analysis of three basic conditions for the formation of debris flow: terrain, source and precipitation conditions, and develop the debris flow formation area, circulation area and accumulation area;2) In accordance with relevant specification and formulas, calculate the dynamic parameters of debris flow, such as flow weight, flow rate, peak flow, size, impact force, ascent and maximum height, to provide a reference for debris flow hazard assessment and prevention engineering;3) Based on the quantitative scoring method and Liu Xilin Debris Flow Hazard Assessment method, conduct the comprehensive evaluation on the risk of debris flow in the Dahe River, and the results show that the risk is at medium level;4) Based on the characteristics of debris flow and the objects of protection in the Dahe River, propose the prevention and treatment engineering measures featuring debris dam + fending groin, to provide a reference for prevention and treatment of debris flow and other geological disasters in the local area.