| Geological disasters in serious threat to human life and property safety,causing many problems such as ground subsidence,urban relocation,traffic damaged,farmland in buried,which hinder the progress and development of the society.Assessment for geological disaster risk is helpful to establish a reliable system and take effective measures of prevention and treatment,which is of great significance to the disaster prevention and mitigation.Taking Qin County as an example,the paper adopts the method of first identification and then assessment.Firstly,by analyzing the characteristics of the disaster points that have occurred,the indirect interpretation signs of geological disasters are extracted by the weighted information method,and then the geological disaster points in Qin County are extracted by visual interpretation based on the GF-2 remote sensing image.Secondly,geological disaster risk assessment has natural attributes and social attributes,which are represented by hazard and vulnerability,respectively.Based on the location information of the correctly extracted disaster points and the disaster-formative points obtained from the field survey,the influence of the disaster-formative geological conditions on the geological disasters is comprehensively analyzed,and the indicators of hazard and vulnerability assessment are obtained.The SVM model was used to evaluate the hazard,and the kernel density analysis method was used to evaluate the vulnerability.Finally,the risk assessment and grading of the study area is carried out,and the assessment results have reference value for the prevention and treatment of geological disasters and land use planning in Qin County.The main results of the research are as follows:(1)The indirect interpretation + direct interpretation geological hazard identification mode was constructed combining the weighted information method and visual interpretation,to accurately identify the geological hazards in the study area,and the recognition accuracy reached 96.81%,laying a solid foundation for risk assessment.(2)The relationship between the impact factors and the spatial distribution of geological disasters is obtained.The research shows that: in the study area,the area with large slope and undulation,the area where the rock and soil type is a single layer of cohesive soil,the residential area and the road buffer area within 100 m,the river buffer area within 500 m,the area with low NDVI value,regions with geomorphological types of beam-shaped loess hilly areas and eroded,accumulated river valleys are more likely to occur geological disasters.(3)Quantitative estimation results of geological hazard risk in Qin County are obtained and graded.Among them,the high-risk areas of geological disasters account for 17.42% of the total area of the study area,and are mainly distributed in the eroded and accumulated river valleys,beam-shaped loess hilly areas,denudation-erosion low-middle mountainous area,and areas with active human engineering activities in the middle of Qin County;The risk area accounts for 46.70%,mainly distributed in the denudation-erosion low mountainous area,the denudation-erosion low-middle mountainous area,and the beam-shaped loess hilly area;the low-risk area accounts for 35.88%,mainly distributed in the denudation-erosion middle mountainous area and the denudation-erosion low-middle mountainous area at the boundary of the study area. |
