Landslide Susceptibility Mapping In Baxie River Basin

Baxie River Basin is a typical area of landslide intensive development in Linxia Basin,Longxi area,Gansu Province.The landslides are widely distributed,activities are frequent,threaten the safety of life and property of local people.In order to effectively formulate the macro-control policy of regional landslide hazard,we need to make regional zoning for landslide hazard.The application of GIS has greatly improved the working efficiency of landslide susceptibility evaluation and provided scientific basis for landslide disaster prevention and control.Based on the field investigation and remote sensing interpretation,the location,quantity,distribution and scale of the landslide in the Baxie River Basin were identified,and summarized the types and distribution characteristics of landslides in the basin.This paper extracted landslides conditioning factors through data integration of remote sensing,topography and geology.Slope unit was used as the evaluation unit,a total of 249 landslides were detected,70% of landslides were randomly selected to construct evidential belief function(EBF),frequency ratio and certainty factor models,while the remaining 30% were used for the model validation.The landslide susceptibility maps were generated.At the same time,success rate curve and prediction rate curve were applied to validate the accuracy of the landslide susceptibility map,and the credibility degree of the models were discussed.(1)The landslides linear distributed along the river valley,most of which are medium-deep seated and configure a large-medium scale.The landslides on both sides of the river show asymmetric development and the large landslides are more likely occur at the gully entrance.The large,deep landslides are mostly distributed in the the middle and lower reaches of thick loess.At the same time,it shows low stability after sliding in the same place.Landslides in Baxie River Basin were formed in several periods,during which the later formed always remould the earlier formed back and forth.(2)The distribution of landslides is closely related to the landform and physiognomy,presenting a high concentration in the ranges of elevation 2000~2200m,slope angle 15°~30°,relief amplitude 100~200m,sunny slope,cutting depth 50 ~100m and gully density 1~ 2.5km/km2.In addition,the distribution of landslides correlates well with the lithology,vegetation covering and human activities,especially with the lithology of Malan loess and mudstone,Normalized Difference Vegetation Index of 0.2~0.3 and scope that 0~600m distance from the roads.(3)The final landslide susceptibility map was classified into five susceptibility regions: very low,low,moderate,high,and very high.The area under the success rate curve for the EBF,frequency ratio and certainty factor models are 0.8038,0.7924 and 0.8088 by Calculation.The area under the prediction rate curve for the EBF,frequency ratio and certainty factor models are 0.8056,0.7922 and 0.7989.It can be seen that the landslide susceptibility maps obtained by the three models is similar to the response and prediction of the spatial distribution of the landslide,and the area under the curve is very close.However,the comprehensive evaluation of success rate and prediction rate,EBF model performs slightly better than other models.