Research On Risk Assessment Of Regional Debris Flow In The Reservoir Area In Alpine And Gorge Region

Debris flow disasters are most frequent in the western region of China,most of which occur in mountain slopes and valleys.The study area of this paper is Baihetan Hydropower Station Reservoir area,which is about 180 km long from the head to the tail of the reservoir.The terrain of this area is complex,and the debris flow breaks out frequently,which causes great losses to property and life safety.Therefore,it is an important issue to study the debris flow in this area.The risk assessment of debris flow is a common way of qualitative and quantitative analysis of debris flow.It can effectively reflect the current state of debris flow in the region and the future development trend of debris flow in the basin.This paper takes the debris flow in the reservoir basin as the research object.First of all,through the analysis of the landform,structure,meteorology,hydrology,vegetation and other conditions in the study area,establishes a three-dimensional visualization model of the reservoir area,interprets the occurrence of debris flow in the reservoir area,and determines the accuracy of the interpretation results through field investigation.In the next place,based on the interpretation results and field investigation reports,the influencing factors of debris flow development in the reservoir area are roughly defined,and appropriate laboratory tests are established to explore the parameters affecting debris flow accumulation in the reservoir area.Finaly,through the above methods,the risk evaluation index of debris flow in the reservoir area is determined and the weight of each index is calculated.The extension theory is introduced to establish the risk assessment model of debris flow in the reservoir area,and the risk of debris flow in the reservoir area is analyzed.At the same time,the risk assessment of other rivers and gullies in the reservoir area has not been carried out on-site investigation.The main research contents are as follows:(1)Based on the data collected in the early stage,a three-dimensional visualization model of the study area is established by using the software to interpret the remote sensing image of the debris flow in the reservoir area and analyze the occurrence of the debris flow in the reservoir area.Through on-site investigation,analysis and evaluation of interpretation results and accuracy,further analysis of the characteristics and development of debris flow in the study area,roughly determine the main factors affecting the occurrence of debris flow in the reservoir area.(2)The experimental model was established,and the influence of different debris flow variables on debris flow accumulation was further confirmed through the design of laboratory tests.Based on this,the selection of debris flow evaluation factors was supported and optimized.(3)Analytic Hierarchy Process and entropy method were used to calculate the subjective and objective weight values of each evaluation factor,and the combined weighting method based on variance maximization was used to calculate the comprehensive weight of debris flow impact factors.Secondly,the extension theory was introduced to evaluate and grade the debris flow risk in the study area.(4)Combined with the field investigation results,and compared with the evaluation results of the method selected in this paper,its accuracy was judged.At the same time,the improved single gully evaluation method of debris flow was used to evaluate the debris flow in the reservoir area to judge the optimization degree of the evaluation model selected in this paper.