| Landslides in the reservoir area have the characteristics of high concealment and great destructiveness due to the periodic fluctuation of water level and the fragile geological environment.Since the implementation of the “West-to-East Power Transmission” project,frequent hydropower development along the Lancang River and the construction of large-scale projects have led to frequent occurrences of coastal landslide disasters and a large scale.Periodic fluctuations of the reservoir water level may induce landslides in the reservoir area,and the deformation and destruction of the landslide in the reservoir area will seriously threaten the downstream hydropower infrastructure and the safety of local people's lives and property.Therefore,detecting the distribution of landslides in the reservoir area and conducting landslide susceptibility evaluation studies are of great significance to the prevention of regional landslide disasters,the safety of people's lives and property in the reservoir area,and the construction and safe operation of hydropower facilities.This paper is based on the time-series InSAR technology to monitor and identify potential landslides in the reservoir area,and proposes a method to evaluate the landslide susceptibility of the radar line-of-sight(LOS direction)deformation rate,topography,hydrology and environmental factors inverted by the time-series InSAR technology.First,the time series InSAR technology is used to invert the deformation of the elevator orbit SAR data covering the 20 km upstream of the Dahuaqiao Hydropower Station reservoir area,and the regional landslide monitoring and identification based on the time series InSAR results,optical remote sensing images of the study area and field survey data;then comprehensive considerations The topography and landslide hazard influencing factors of the study area,select Sentinel-1A lifting rail deformation rate,slope,aspect,elevation,distance from the river and normalized vegetation index7 evaluation factors,and use the binary logistic regression model to determine the regional landslide proneness In the research of performance evaluation,the accuracy of the model evaluation results is verified by the receiver operating characteristic curve(ROC)and the area under the ROC curve(Area Under Curve,AUC)values.The specific research content and conclusions are as follows:(1)Using SBAS-InSAR technology to inverse the surface deformation of the Dahuaqiao Hydropower Station Reservoir in the Lancang River Basin.Taking the reservoir area of Dahuaqiao Hydropower Station as the research area,using SBASInSAR technology to image the 80 scenes from the ESA Sentinel-1A satellite from October 2017 to June 2020 and from November 2018 to April 2020 36 The scene descending orbit image is subjected to interference processing to obtain the surface deformation time series results of the inversion of the descending orbit data in the reservoir area of the Dahuaqiao Hydropower Station.During the monitoring period,the result of the radar line-of-sight deformation rate inversion from the ascending orbit data was-123mm/a?75mm/a,the maximum settlement of the entire reservoir area was-328 mm,and the deformation area and rate of the Dahua landslide was the largest;the descending orbit data was inverted The result of the radar line-of-sight deformation rate is-104mm/a?60mm/a,and the maximum settlement is-250 mm.Through crossvalidation and comparative analysis of the inversion deformation results of the elevator orbit data,it can be known that the deformation results of the elevator orbit data are consistent in the spatial distribution,but have differences in the deformation level and size.Compared with a single platform or track data,the use of The combination of lifting rail data can obtain more deformation information and improve the reliability of landslide monitoring and identification.(2)Identify potential landslides in the reservoir area based on the deformation rate of the lifting rail in the study area,optical images and field survey data.According to the deformation results of the lifting rail inverted by SBAS,combined with field verification and optical image interpretation,a total of 13 potential landslides in the reservoir area of the Dahuaqiao Hydropower Station have been delineated.Among them,7 potential landslide bodies were monitored from the ascending track data,and 6potential landslide bodies were monitored from the descending track data.Among the13 landslides detected,the Lagu landslide,Dahua landslide,and Cangjiangqiao landslide are historical landslides,and the other 10 landslides are new landslides.The results of landslide identification not only update the landslide library in the reservoir area of Dahuaqiao Hydropower Station,but also provide an important basis for the prevention and control of regional landslide disasters.(3)Evaluation and zoning of landslide susceptibility in the reservoir area based on the binary Logistic regression model.Considering the topography and geomorphology conditions of the study area,the effects of water system and vegetation influence factors,select the ascending orbit deformation rate(AVel),descending orbit deformation rate(DVel),slope(SLO),aspect(ASP),elevation(DEM),distance to water system Seven factors of distance(EDIS)and normalized vegetation index(NDVI)were used to establish a landslide susceptibility evaluation model in the reservoir area.The evaluation results divided the landslide proneness degree of the reservoir area into 5different grades,namely,extremely high-prone areas,high-prone areas,medium-prone areas,low-prone areas and extremely low-prone areas.The results show that the study area as a whole belongs to a very high-prone area,and historical landslide points fall in it;20% of the sample data is selected as the gold standard for ROC curve verification,and the area under the ROC curve has an AUC value of 0.864,which can meet the accuracy of the landslide susceptibility evaluation.It is required that the evaluation of landslide hazard susceptibility and the results of zoning can provide an important basis for the prevention and control of landslide hazards in this area. |
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