Multi-model Comprehensive Assessment Of Susceptibility To Geological Disaster In Maerkang City

Located in the southern margin of the northwestern Sichuan Plateau,Maerkang City is one of the typical regions of the agricultural and animal husbandry belt in the southwest.The ecological and geological environment is fragile and the geological disasters is easy to occur,which has a serious impact on local production activities,therefor the assessment of susceptibility to geological disasters is very necessary.At present,the assessment of susceptibility to geological disasters in the study area does not provide an in-depth analysis of the formation conditions of geological disasters and lacks the assessment of necessary basic conditions;susceptibility assessment models are mostly based on qualitative assessment models,and quantitative assessment research is lacking.Therefore,this article takes the geological disasters of Maerkang City as the research object,through RS and GIS technology,analyzes the relationship between geological disasters and formation conditions in detail,and selects and grades the impact factors;With the help of computer programming technology,to carry out quantitative analysis and evaluation of geological disasters by the three models of support vector machine model(SVM),certainty factor and support vector machine coupling model(CF-SVM),information method and support vector machine coupling model(I-SVM),and suggestions on prevention and control of geological disasters were put forward on this basis.This study can provide theoretical reference significance for the subsequent exploration of the assessment of susceptibility to geological disasters;it can also effectively understand the local geological disasters susceptibility level,avoid or reduce the loss of life and property,and provide a reference for its land and space planning,scientific disaster prevention and mitigation.The main achievements of this paper are as follows:(1)The point density of landslides,collapses and debris flows in the study area were 1.58/100km~2,0.24/100km~2,3.08/100km~2,geological disasters were mainly distributed on both sides of rivers and roads,the distribution is very uneven and the watershed control is obvious and the overall density of geological disaster points is characterized by north-south high and east-west low.(2)Through qualitative and quantitative analysis of the ratio of the number of geological hazards and the grading area ratio curve of each impact factor,and counting the frequency of geological disasters under the impact factor,the 12 impact factors are grading;on this basis,the SPSS analysis tool is used to analyze the relationship between each factor correlation analysis,remove the slope length and profile curvature with high correlation,and use the remaining 10 influencing factors to construct a geological disaster susceptibility assessment index system.(3)Based on the Matlab platform,the optimal kernel function and optimal parameters of each model are obtained through the grid method and the cross validation method(CV,Cross Validation),and constructed respectively the SVM,CF-SVM,and I-SVM models.The geological disaster susceptibility results predicted by the three models have similar spatial distribution characteristics,among them,the extremely high susceptibility areas are mainly concentrated in areas with low altitude and intense human engineering activities,and the extremely low susceptibility areas are mainly distributed in high mountains and extremely high mountains,sparsely populated or unpopulated areas.(4)Through ROC curves and the features of prone partitions respectively,the accuracy analysis and rationality verification of the susceptibility assessment results of the three models of SVM,CF-SVM and I-SVM.According to the research results,the AUC values of the three models are 0.765,0.862,and 0.828,and the relationship between the density of geological hazard points and the susceptibility zone of the model is analyzed by comparison.Finally,based on the development of geological disasters in the study area and the results of susceptibility zoning,suggestions for geological disaster prevention and control by zoning and classification are proposed.