Study On Risk Assessment And Control Measures Of Debris Flow In Yantu Ditch,Wudu District,Longnan

Debris flow is a common geological disaster in mountainous areas in my country.It has the characteristics of suddenness,destructiveness,and short duration.Once it erupts,it will have a great impact on the ecological environment,economic construction and personal safety.The Yantugou valley in Wudu District of Longnan City has rich material sources and large gully bed gradient.Local instantaneous rainfall occurs frequently in the area,resulting in frequent debris flow disasters in Yantugou.In addition,the mouth of the ditch is where Xiaoshanping Village is located.Residents are dense,and mudslides will cause heavy casualties and economic losses.This paper takes the debris flow in Yantugou in Wudu District of Longnan as the research object.Based on field investigation and related data collection,the geological background of the study area is obtained,the formation conditions of the debris flow are analyzed,and the movement characteristic parameters of the debris flow are calculated.Establish a two-level fuzzy comprehensive evaluation model suitable for the risk evaluation of debris flow in Yantu ditch,reasonably determine the weight of each evaluation index,and compare the evaluation results with the quantity in Appendix G of the"Debris Flow Hazard Prevention Engineering Survey Specification"(DZ/T0220-2006)The comprehensive evaluation method and the calculation results of the traditional Liu Xilin evaluation model are compared and verified.At the same time,on the basis of obtaining the calculated parameters,a targeted treatment design for the debris flow disaster in Yantu Ditch is proposed.The research results obtained in this paper are as follows:(1)Yantu ditch belongs to the first-level branch ditch on the right bank of the Bailong River.It is a seasonally flowing valley with veins.The main ditch is 1.93km long,the basin height difference is 1692m,the average slope of the main ditch bed is 237‰,and the basin area is 2.52km~2.(2)The Yantugou watershed has relatively large elevation differences,strong valley cutting,development of unfavorable geological phenomena,and large and concentrated waste residue accumulation,which provides good provenance and topographic conditions for the occurrence of debris flow.Heavy rain is the main feature of precipitation in this area.The water source in the area is extremely rich,which provides favorable water source conditions for the outbreak of debris flow.(3)Combining the actual situation of the debris flow in Yantu ditch,analyze the various factors that affect the debris flow,select the factors that have a greater impact on the debris flow risk as the evaluation index,establish an evaluation model,and conduct a secondary fuzzy comprehensive evaluation of the debris flow risk in the Yantu ditch.Comparing the evaluation result with the quantitative comprehensive evaluation method and the calculation result of the traditional Liu Xilin evaluation model,the three evaluation results have good consistency.The results show that the selection and establishment of the evaluation model can better reflect the actual situation of the debris flow in Yantu Ditch.(4)Based on the characteristics of debris flow characteristics and the principles of control engineering layout,comprehensively consider the specific characteristics of Yantu ditch debris flow,the geological conditions of the prevention and control project area and the hazard objects,and adopt a comprehensive treatment design combining"block+drainage+protection"for Yantu ditch debris flow.