Quantitative Risk Assessment Of Debris Flow Disaster Of Yuzi Gully In Dachuan Town Of Zhouqu County

The risk assessment of debris flow disasters is one of the hot issues in the study of debris flow disasters.The Zhouqu section of the Bailong River Basin is one of the most serious areas of debris flow disasters in China.At present,there are still a large number of villages and towns in the area gathered on the debris flow fans of different scales,directly threatened by mudslides.Therefore,the selection of typical valleys in the Zhouqu section of the Bailong River basin,the risk assessment of debris flow disasters is not only of theoretical significance,but also of practical value.Zhaizigou is located in the territory of Zhouqu County.The dumping fan is the seat of the town government.The population and buildings are densely distributed.The provincial road 313passes through the middle of the fan.At present,the loose material in the ditch is widely distributed.In the event of extreme rainstorm,it is easy to cause The blockage of the Bailong River channel causes major damage.Therefore,this paper selects the scorpion ditch as the research object and based on the risk assessment framework of debris flow hazard.Based on the evaluation of debris flow hazard and disaster vulnerability,the risk assessment of debris flow hazard is carried out.FLO-2D,a well-recognized debris flow motion simulation software at home and abroad,was used to simulate the movement characteristics of debris flow in the Zizigou under the conditions of 10 years,20 years,50 years and 100 years of rainfall.The magnitude of the force assesses the danger of debris flow hazards.Select the property,population,and river channel as risk assessment units to calculate the vulnerability values of different types of risk units under different working conditions.Based on the superposition function in the GIS platform,the quantitative risk assessment of the debris flow disaster in the Zizigou is realized.The main research results of the paper are as follows:(1)The mud depth is larger at the intersection of the channel and the intersection of the channel and the river,and gradually increases from the circulation area to the accumulation area.As the intensity of rainfall increases,the depth of the mud increases gradually,especially at the intersection of the channel and the river.In the 50-year and 100-year-old rainfall,the depth of the mud exceeds 10m,covering the entire channel,which may cause blockage of the channel.(2)Based on the depth and flow velocity of debris flow,the impact of the impact force on the unit area of the grid unit is selected as the basis for the risk of debris flow disasters,and the risk of the fan from the channel to the stacked fan is gradually reduced.With the increase in rainfall intensity,the degree of danger has increased.There is no high-risk area under the condition of 10 years of rainfall.The area of the dangerous area is 0.05km~2,and the area of low-risk area is 0.25km~2.Under the condition of 20-year rainfall,the area of high-risk area is0.05km~2,the area of medium-risk area is 0.09km~2,low-risk area.The area is 0.39km~2;the area of high-risk area is 0.07km~2 under the condition of 50-year rainfall,the area of medium-risk area is0.11km~2,the area of low-risk area is 0.49km~2;the area of high-risk area under the condition of100-year rainfall is 0.1km~2,the area of dangerous area 0.18km~2,low-risk area 0.59km~2.(3)Statistically analyzing the information of the disaster-bearing body through high-definition remote sensing images,and calculating the property loss,threatening population and river course under four kinds of rainfall conditions from the three aspects of property,population and river course,respectively,in which the loss of rainfall conditions in 10 years was160,300,600 yuan.It threatens a population of 208 people and a river course of 1590m.In 20years,the loss of rainfall conditions was 30,903,200 yuan,threatening the population of 460people and the river channel was 2,260 meters.In 50 years,the loss of rainfall conditions was39,189,560 yuan,threatening 544 people and 2,560 meters of rivers.In 100 years,the loss of rainfall was 707.094 million yuan,threatening the population of 628 people and the river channel was 2770m.(4)Based on the superposition function of GIS system,based on the quantitative evaluation of risk and vulnerability,the overall risk zoning is obtained.With the increase of rainfall intensity,the area of high-risk area in Laozhuang Village has increased significantly,and Tuqiaozi Village as a whole is a low-risk area.Among them,there is no high-risk area under the condition of 10years of rainfall,the area of medium-risk area is 0.03km~2,and the area of low-risk area is0.27km~2;there is no high-risk area under the condition of 20-year rainfall,the area of medium-risk area is 0.05km~2,the area of low-risk area 0.48km~2;the area of high-risk area is0.01km~2 in 50-year rainfall,the area of medium-risk area is 0.1km~2,and the area of low-risk area is 0.56km~2;the area of high-risk area is 0.03km~2 in 100-year rainfall,and the area of medium-risk area is 0.21 km~2,low risk area of 0.63km~2.