Study On Geological Disaster Susceptibility Zoning And Meteorological Early Warning And Forecasting In Cengxi City,Guangxi Province

Cenxi City is located in the southeast of Guangxi.Its geological conditions are complex.The distribution area of sedimentary and granite rocks accounts for about 44.7%and 44.4%respectively.It is a rainstorm-type geological hazard-prone area in Guangxi.Field investiga-tion shows that there are 814 geological disasters and potential geological disaster sites in the area,in which 332 collapsed(the largest number),246 landslides,203 unstable slopes,22 debris flows and 11 ground collapses.At present,the geological disasters in Cenxi City still threaten the lives of about 8,100 people and the property safety of more than 7 million yuan.Based on the detailed investigation data of geological disasters in Cenxi City from 2013 to 2014,The relationship between geological hazards and several influencing factors such as topography,geotechnical types,geological structures,human engineering activities was studied.Based on the statistical data of cumulative rainfall stimulating geological hazards,an early warning and prediction model of geological hazards in Cenxi City is established.It is aim to make early warning and forecast for the occurrence of geological disasters in Cenxi City.Through this study,the following conclusions are drawn:1.The time distribution characteristics of geological disasters in Cenxi City are as follows the collapses and landslides mainly occurred in the last 10 years,and were most prominent in 2010.Most of them were occured in June to August every year.2.The spatial distribution characteristics of geological disasters in Cenxi City are as follows:1)Geomorphologieally:most of them occur in the middle and low mountain areas of tectonic erosion;2)Lithologically:geological hazards mostly occur in the distribution area of massive hard granite,and mostly occur in the weathering crust of granite.3)Causes of formation:the geological disasters are mainly affected by concentrated rainfall and human activities.For example,it is easy to happen in rainstorms,it is easy to cluster and distribute densely along the highways,and it is easy to distribute in a planar way in residential areas.Generally speaking,in the ares with granular granite formations and extremely soft and strong weathering zones,the thicker of residual soll is,the stronger the human engineering activities are,and the more geological hazards develop.Based on the above analysis,eight sub-factors were selected.The weights of factors were quantitatively calculated by the expert scoring method combined with the analytic hierarchy process(AHP).Combining with the field calculation function of ArcGIS and the weighted method(R=(?)YiWi),the comprehensive evaluation value of geological hazard susceptibilityin the study area is calculated.Then the susceptibility of geological hazards in Cenxi City is divided into zones.In the analysis of inducing factors,through statistical analysis of the relationship between the cumulative rainfall on the same day and the number of geological hazards such as landslides and landslides,the critical rainfall of the geological hazards in Cenxi City is 70 mm and 130 mm(the cumulative rainfall on the same day).Finally,the possibility of geological hazards in Cenxi City is evaluated by the method of information quantity,and the meteorological early warning and forecasting model of geological hazards in Cenxi City is established.