Risk Assessment Of Geological Hazard In Zhenyuan County Based On GIS

Zhenyuan County is located in the Longdong Loess Plateau,the terrain is high in the northwest and low in the southeast.The hilly and gully area is widely distributed in the county.The important reason for the serious geological disasters in this area is closely related to the fragile geological environment conditions.This paper takes the geological hazards in Zhenyuan County,Qingyang City,Gansu Province as the research object and summarizes the characteristics and distribution of geological hazards in Zhenyuan County.And with the help of Arc GIS and SPSS software,the geological hazard risk assessment of Zhenyuan County is carried out.The main conclusions are as follows:(1)Geological hazards and hidden dangers in Zhenyuan County include 8 collapses(7%),7 debris flows(6%),39 landslides(32%),47 unstable slope hidden dangers(39%),and19 ground cracks(16%).And human engineering activities are the main inducible factors.In space,It is mainly distributed along the banks of the Pu River,on both banks of the Ru River and on both sides of its main tributaries,as well as in the piedmont areas of the hilly and gully areas on both sides of the Ru River.In terms of time,about 80%mainly occurred in July to September when there was more rainfall.(2)Using the data processing function of Arc GIS and the statistical analysis function of SPSS,the risk and vulnerability division of Zhenyuan County was conducted.8disaster-causing factors were selected to divide Zhenyuan County into extremely high,high,medium,low and dangerous areas by analytic hierarchy process.The areas with high risk were mainly distributed on the plateau,beam and ridge on both sides of river and valley.Taking each township as the evaluation unit,4 disaster bearing factors were selected to divide Zhenyuan County into extremely high,high,medium and low vulnerable areas by systematic cluster analysis method.The areas with high vulnerability were mainly distributed in Chengguan Town.(3)By using the raster calculator tool of Arc GIS and using the risk=hazard×vulnerability function,the superposition calculation of the risk and vulnerability zoning results was performed.Zhenyuan County was divided into extremely high,high,medium and low risk areas,of which the extremely high risk area was 161.78km~2,accounting for 4.61%of the total area of Zhenyuan County,distributed in most parts of Chengguan Town,new urban and rural areas,and Guoyuan Township.The area of high risk area is 1120.31km~2,accounting for 31.95%of the whole area of Zhenyuan County,which is distributed throughout the whole region,mainly in the northern towns such as Maqu Township;The area of the middle risk area is 1458.40km~2,accounting for 41.60%of the total area of Zhenyuan County,which is concentrated in the central and southern part of the whole district.The area of low risk area is765.50km~2,accounting for 21.84%of the whole area of Zhenyuan County,which is mainly distributed in the towns and townships such as Yinjia Town and Town in the north.