Landslides Characteristics And Landslides Susceptibility Assessment In The Upperstream Catchment Of Minjiang River

The upperstream catchment of Minjiang River is characterized by high mountains and canyons.The geohazards(e.g.,landslides,rockfall,debris,etc)are frequently occurred under fractured rockmasses,strong neotectonic movement,and complex natural environment in this catchment,where induced by earthquake,rainfall,and human activities.There are densely residential village in the upperstream catchment of Minjiang River.Therefore,the safety of resident,economic,and social development will be servely threated by these geohazards.Therefore,it is necessary and urgent to carry out the characteristics of landslides development and the assessment of the landslides(including rockfall at here)susceptibility in the upperstream catchment of Mingjiang River,which will effectively and scientifically reduce risk of geohazards.Based on the study and summary of previous research results,this paper uses GIS technology to quantitatively analyze the relationship between geological disasters and geological environment in the study area.With the integrated adoption of Arc GIS,MATLAB,SPSS software,we evaluate the landslide susceptibility in the upperstream catchement of Mingjiang River by using Frequency Ratio(FR),analytical hierarchy process(AHP),and logistic regression(LR)models.Then,the landslide suscepitiblity was graded and zoned in the study area..In this paper,the following main results are achieved:(1)A relatively complete and detailed landslides inventory in the upperstream catchment of Minjiang River has been established.5307 landslides have been identified found,with a total landslide area of 63.4905km~2.(2)The engineering geological environment database of the study area has been established,including elevation,slope,aspect,curvature,topographic relief,normalized difference vegetation index(NDVI),topographic wetness index(TWI),distance from rivers,distance from faults,lithology,annual average rainfall,Wenchuan earthquake PGA,and distance from roads,and distance from townships.(3)In the study area,most of the landslides are frequently distributed in the elevation of 1335m?1700m,slope of 60°?90°,curvature of-36?-1,terrain fluctuation of 400m?881m,NDVI of 0.25?0.3,terrain wetness index of 1.5?4,distance from rivers of 200m?300m,distance from faults of 0?1km,Sinian,annual average rainfall of 447mm?500mm,Wenchuan earthquake PGA of 0.4g?1.2g,distance from roads of 200m?300m,and distance from townships of 0?1km.Overall,with the increase of slope,topographic relief and Wenchuan earthquake PGA,the distribution of landslides is more intensive;the closer to rivers,faults,roads and townships,the more landslides.(4)The area under ROC curve(AUC)is used to test the results of three evaluation models.AUC values of FR model,AHP model and LR model are 0.901,0.904,and 0.923,respectively.It shows that the prediction accuracy of the three models is very high,and the prediction accuracy of the logistic regression model is the highest.The calculation results of the logistic regression model provide a reliable scientific basis for the engineering construction and geological disaster prevention in the study area.(5)It is concluded from the comprehensive analysis of the results of the three models that the landslides are easy to occur on both sides of the road in the study area,especially along the main stream of Minjiang River which is located in Diexi-Fengyi-Weizhou.The landslides in the study area pose a great threat to the national road 213 and the farmers living along the Minjaing River.