Hazard Assessment Of Geological Disasters In The Yalong River Basin From The Maidilong To Kala.Based On GIS

The Kala region is located in the east of Qinghai-Tibet Plateau,which suffers fierce –great fierce ersion like other mount area. The Yalong River flows from northwest to southeast across this area.Vast of valleys cut down the earth’s surface up to 2000-3000 meters,which leads to some kinds of geological hazards in this area.Owing to the steep slope,the energy of water is plenty,and many large hydropower station have been planed to be built,including the Kala hydropower station in the research area.So the hazard assessment of the YalongRiver from Maidilong to Kala can reduce the loss of local people caused by geological hazard,which can also provide reference to some engineering construction in this area in the future.Based on the wild field investigation andindoor data processing,the article mainly focus on 137 geological disasters.A model of present hazard assessment is bulit by using the methods information quantity method and analytic hierarchy processand;a predictive model of hazard assessment is also built by using the methods logistic regression and analytic hierarchy processand.Both these models make sense when they are jioned to the Arcgis software. The conclusions of the research are as follows:Establish the GIS datebase about basic geological data of research area. The datebasecontains natural geographical background,basic geologicalenviron-me nt.geological disasters,intermediate operations layer and classification of hazard assessment.The datebase makes it convenient when it comes tomanage-ng,retriev ing,querying date.It also works for disastersanalysing andclassifica-tion of hazar d assessment.Summarize the characteristics of regional geological disasters.Considering the 41 landslide,90 rockfall,and 6 debris flow,the rasearch shows that:①most of the disasters happen from June to September.②The landslide tend to appear on the right bank of the Yalong River,and it also appears at different kinds of slope structure;The rockfall is general a tiny scale and appears at rock slope below the hight 2500 meters along the tributary;Debris flows on the left of the Yalong River are general large scale and appear in the valley,while debris flows on the rigth of the Yalong River are generally tiny scale and flow on the slope mainly.Induce evaluationfactors to geological disaster.The aiticle chooses gradient,slope structure,new Tectonic movement,rock nature,the fault,the river,the rainfall,the earthquake,human project. The vegetation coverage and the debris as the evaluation factors.The summarization shows that:①the landslide is most likely to happen at a slope of 30-40 gradient,forming by rock of Zagunao or Loose debris;②The rockfall is most likely to hanppen at a slope of graeter than 40 gradient,below the hight of 2500 meter,forming by the rock of Zagunao;③The debris flow is most likely to happen at a slope of 30-40 gradient,3-4 debris per square kilometers,and higher than 800 mm of rainfall per year.The results about hazard assessment of geological disasters.The result of present assessment and prediction both show that:the landslide,rockfall,and debris flow are most likely to happen along the Yalong River and the entrance of some valleys.The upstream of valleys and areas of high location suffer little from the geological disasters,as the whole slope is stable and unlikely to deform.