Susceptibility Assessment Of Landslide Hazards In Lanzhou Area Based On GIS

Because of its complex geological structure,large relief,strong human activities,frequent geologic hazards,Lanzhou is one of the most serious geological hazard in northwest China.In this study,we choose Lanzhou area and the surrounding as the research object,used the 1:50,000 DEM data and the remote sensing image,based on ArcGIS and ENVI platform,extract several factors of disaster environment,such as slope,aspect and so on;Second,we combined the disaster environment factors layer and historical disaster data to study the characters of spatial distribution of geologic hazard;Third,suitability analysis of topographic factors to geo-disasters was carried out with the method of sensitivity index(SI),certainty factor(CF)and correlation coefficient in the study area of geo-disasters,precision analysis resulted on ROC curve;Finally,we used the remote sensing images in Lanzhou area in 2000?2008?2013year to analyze the vegetation coverage change based on ERDAS,Come to the conclusion:(1)In Lanzhou area,geologic hazards are easily occurred in 25°~40°slope,1700m~2600m elevation,15m~45m RDLS,5m~30m cutting depth,southeast?south?southwest sunny convex slope.(2)It is concluded that the best suitable topographic factors for geo-disaster in the study loess area are: slope,aspect,SOS,elevation,RDLS and cutting depth.(3)The assessment results of the three models were compared and it can be seen that the sensitivity distribution of geological hazards is basically consistent.The area under the ROC curve of the IM is larger,and the LR is second,and the PI is slightly lower.From its accuracy,it shows that the IM is slightly higher than the LR,and the lowest is the PI.(4)The assessment results show that the county(district)located in the higher prone areas of geological hazards are: Chengguan district,Xigu district,Yongdeng county;the high prone areas of geological hazards are: Qilihe district,Anning district;Gaolan county is located in the prone areas;and the relatively stable area is Yuzhong county.(5)During the 13 years,the vegetation in North and South Mountains are general in a growing trend,and the inferior vegetation changed greatest.In 2013,the vegetation in the two mountains entered a good growth period;greening and ecological restoration produced good results.Because the green consciousness of people are constantly improving,the heavily growing investment ? the ecological protection and recovery job of government played an important role in vegetation restoration.