Evaluation Of Soil Erosion And Landslide Susceptibility In Dongzhi Plateau Based On GIS And RS Technology

Dongzhi plateau,located in the hinterland of the Loess Plateau in the east of Gansu Province,has the characteristics of collapsibility,porosity and vertical joints.It is the prone place of landslide,debris flow,collapse and other geological disasters.In recent years,people's over exploitation of land resources makes the soil erosion situation of Dongzhi plateau further intensified,landslides and other geological disasters also occur frequently,the area of the plateau is constantly swallowed up,and people's lives and property safety are under great threat.Therefore,it is of great significance to study the soil erosion and the occurrence of landslide disasters in Dongzhi plateau for the protection of land resources and the safety of people's lives.In this study,the revised universal sediment loss equation(RUSLE)was used to quantitatively analyze the soil and water loss in Dongzhi plateau,and then the analytic hierarchy process(AHP),information model(I),certainty coefficient method(CF),information logic regression coupling model(I-LR)and certainty coefficient logic regression coupling model(CF-LR)were used to evaluate the landslide hazard susceptibility in this area Finally,the relationship between soil erosion and landslide susceptibility is discussed through the division of sub basins.The main conclusions are as follows:(1)In 2019,the soil erosion modulus of Dongzhi plateau is in the range of 0-41012.4 t·km^-2·a^-1,the average erosion modulus is 4530.18 t·km^-2·a^-1,the annual erosion is 12.8334 million tons,and the annual sediment loss is 9.7110 million tons,which is a relatively serious soil erosion area.Soil erosion in the region is mainly affected by terrain factors.With the increase of slope,the area proportion of micro and light erosion areas in each slope area continues to decrease.The proportion of moderate,intensive and extreme intensity erosion shows a trend of first increasing and then decreasing,while the area proportion of severe erosion areas continues to increase.(2)The evaluation results of AHP model,I model,CF model,I-LR model and CF-LR model all reflect that the landslide susceptibility of Dongzhi plateau presents the spatial distribution characteristics of"high valley and low tableland surface"on the whole,and in the gully area,the closer the river is,the greater the slope is.However,through the rationality test and accuracy test of the five models,it is concluded that CF-LR coupling model is better than other models.The calculation results of the model show that the landslide susceptibility in Dongzhi plateau area presents the characteristics of"polarization".The areas of high and high susceptibility areas are 775.20km² and 694.55km²respectively,accounting for 51.63%of the total area,and the areas of very low susceptibility areas are 968.1%The area of low and middle risk areas is small,accounting for only 14.36%of the total area.(3)The spatial distribution of the mean values of erosion modulus and CF-LR index in each sub watershed is characterized by"high in the north and low in the South".The CF-LR value of landslide susceptibility is also higher in the sub watershed with high soil erosion degree,and the occurrence of landslide disaster will be affected by soil erosion to a certain extent.Through the analysis of the relationship between soil erosion and historical landslide disasters and the evaluation results of landslide susceptibility,it can be concluded that soil erosion promotes the formation of landslide disasters to a certain extent.The relationship between landslide density and soil erosion intensity in each erosion intensity area is exponential,and the landslide susceptibility index increases linearly with the increase of soil erosion modulus.