Geological Hazards Monitoring And Dynamic Susceptibility Assessment In The Bailong River Basin Based On Multi-source Remote Sensing

This paper takes the middle and upper reaches of the main stream of the Bailong River basin in southeastern Gansu Province and the tributary basins of the Minjiang River as the study area.Based on field surveys,optical remote sensing data and InSAR time series deformation data are used to identify and monitor geological hazards.Based on this,the dynamic evaluation of the susceptibility of geological hazards in the study area has been completed.The main results achieved are as follows:(1)Use optical remote sensing to monitor and realize the "general survey" of geological hazards in the whole region.The characteristics of different geological hazard types or of the same hazard type with different activity intensity on remote sensing images are summarized.Reveals the temporal and spatial distribution of geological hazards:In terms of space,geological hazards are densely distributed on both sides of rivers,weak and broken stratum,and active faults;In terms of time,geological hazards develop intensively in months with heavy rainfall and at night when heavy rains occur frequently.A prediction model for the scale of geological hazards was constructed,which realized that the scale of hazards in the study area could be expressed quickly and quantitatively with fewer factors,and the results were verified to be reliable.(2)A criterion for identifying geological hazards based on the time-series InSAR technology is put forward.The PS-InSAR technology is used to obtain a linear deformation rate map of the whole area,and the geological hazards are delineated based on the geological background of the study area.The "detailed investigation" of geological hazards has been realized and the interpretation results of optical remote sensing have been supplemented.The monitoring results show that there is no regional large deformation in the study area as a whole.The deformation rate along the Bailong River and Minjiang River basins is relatively high,and geological hazards are prone to occur when affected by rainfall and other factors.Taking the Xieliupo landslide as an example,the landslide time series deformation characteristics analysis and evolution mechanism research were carried out,and it was pointed out that the landslide deformation was closely related to the activities of the fault zone and rainfall.(3)The advantages and disadvantages of the Information Model,the Certainty Coefficient Model,and the Weight of Evidence Model in the assessment of the susceptibility of geological hazards are compared and analyzed.Considering the most fundamental hazard-generating environmental conditions that affect the development of geological hazards.The slope height,slope,stratum lithology,distance from faults,gully density,and normalized vegetation index are selected as the evaluation factors of landslides.The areal density of loose source,stability of loose material,average gully gradient,and soil erosion capacity are used as the evaluation factors of debris flow.On this basis,the status of each evaluation factor is graded.(4)Based on the selected evaluation factors and evaluation models,firstly carry out regional susceptibility evaluations for landslide hazards,and conduct accuracy tests on the three evaluation results.After comparative analysis,the most suitable information regression model for the study area was selected to evaluate the susceptibility of regional debris flow.The two evaluation results are combined to obtain the evaluation results of the susceptibility of regional geological hazards.Kriging interpolation is performed on the time series linear deformation rate,the distribution of the regional deformation rate is obtained,and it is introduced into the original susceptibility evaluation result.A dynamic evaluation model of the susceptibility of geological hazards was constructed,and the results of the susceptibility evaluation in time series were obtained.This model effectively reduces the negative bias in the evaluation of the susceptibility of geological hazards,and improves the accuracy and reliability of the evaluation results.