Risk Assessment And Mitigation Of Debris Flow In Qinglingou Under The Influence Of Rainfall And Treatment Projects

Debris flow is a very sudden and destructive disaster phenomenon,and the debris flow after the earthquake has the characteristics of large scale and large danger range.Scientific geological disaster risk assessment can comprehensively evaluate the relationship between disasters and social economy,and provide an important basis for disaster prevention and mitigation of mudslides and mountain living planning.In this paper,the "9.24" debris flow in Qinglingou is selected as the research object to simulate the debris flow under different rainfall conditions.The "7.11" debris flow in Qinglingou is selected as the research object to simulate the debris flow under different engineering conditions.According to the results of numerical simulation,the risk evaluation model was established.Combined with the on-site socio-economic survey,the vulnerability index and the social vulnerability were used to establish the vulnerability evaluation index system.Finally,according to the risk and vulnerability results.Calculate the risk value of the debris flow in each building under different conditions.According to the risk value and the change of the debris flow over the years,the existing disaster reduction benefits of the governance project are analyzed,and the disaster reduction measures are proposed.The research results are as follows:(1)As the rainfall frequency increases,the increase range of accumulation range and accumulation depth gradually decreases,and the proportion of dangerous areas in residential areas gradually increases(10% in 10 years,23% in 20 years,32% in 50 years,100)The year is 41%).(2)The existing treatment project has a remarkable effect under the condition of 10 years of rain,but it cannot meet the fortification requirements under the condition of 20 years of rain.In the case of 20 years of rain,raising the 2# dam to 11 m can meet the fortification requirements.(3)The vulnerability is closely related to the type of building and the number of people.The low-volume area is mainly located near the mouth of the debris flow.The vulnerability of the river area is generally intermediate-level vulnerable area and high-level vulnerable area.(4)Most buildings in residential areas are located in risk-free and low-risk areas.The medium and high risk is mainly located near the Mizoguchi,and as the distance from the residential area to the Mizoguchi increases,the risk value of the residential area gradually decreases.The construction of 1# dam has little impact on the risk value of debris flow in residential areas.Under the condition of 10 years of rain,the construction of 2# dam will make the risk value of debris flow in residential area become zero,but the proportion of debris flow risk area under the condition of 20 years It is 46.55%.(5)The existing treatment project has a good disaster reduction effect,and the construction of the 1# dam effectively weakens the river blocking effect of the debris flow.The 2# dam played the role of intercepting the debris flow,and the disaster reduction benefit can reach100%,but the disaster reduction benefit is only 11.75% in the first 20 years.According to the current situation of Qinglingou channel,it is still necessary to do a good job in monitoringand early warning of debris flow in the area,timely siltation of the barrier lake and the ditch,and engineering treatment of the branch ditch.In the design of the debris flow prevention and control project after the earthquake,a combination of “stable and blocked” should be adopted,and the influence of the dynamic reserve on the movement of the debris flow needs to be considered.