| The traditional monitoring of potential geological hazards is usually based on a single kind of remote sensing data or technology,lacking comparative research on multiple data sources and methods.Thus,based on Sentinel-1A ascending and descending orbit data,we adopted a variety of interferometric synthetic aperture radar(InSAR)technologies currently available,combined with high-resolution optical satellite images and drone images,to carry out the research on the potential geological hazard monitoring based on multiple data sources and InSAR technologies in the entire area of Dujiangyan City,and some areas of Wenchuan County and Mao County in this thesis.The main research content and results are as follows:(1)In view of the the problems that different InSAR technologies may have different optimal algorithm model parameters in different elevation intervals,we explored the corresponding optimal algorithm model parameters for differential interferometric synthetic aperture radar(D-InSAR),persistent scatterer interferometric synthetic aperture radar(PS-InSAR),small baseline subset interferometric synthetic aperture radar(SBASInSAR),distributed scatterer interferometric synthetic aperture radar(DS-InSAR)technologies in the areas that below 1 000 m,between 1 000 and 3 500 m,and above 3500 m of the study areas in this thesis.The surface deformation monitoring researches on the study area were conducted from January 2018 to December 2020 for ascending orbit and from March 2018 to December 2020 for descending orbit.The experimental research results indicated that the deformation monitoring results of the same InSAR technology in the selected study area were similar,and the deformation trends of different InSAR technologies were also similar,while there were certain differences in the deformation rates monitored by different InSAR technologies.(2)In view of the current lack of identification and monitoring of potential geological hazards in the study area of Northern Sichuan,the application of InSAR potential geological hazard monitoring based on the results of InSAR surface deformation monitoring in the research area was conducted.Forty-nine potential geological hazard points were identified in this thesis,of which 38 were known geological hazard points.Among these 49 potential geological hazards,there were 2 landslides and 1 collapse in the elevation range below 1000 meters,and 1 debris flow,2 collapses,and 43 landslides in the elevation range of 1000 to 3500 meters.(3)In view of the lack of evaluation of the applicability of different InSAR technologies in the study area of Northern Sichuan and the insufficient comprehensive monitoring and analysis of typical potential geological hazards,the applicability of different InSAR technologies in the different elevation intervals was studied.The experimental research results of this thesis showed that: D-InSAR and DS-InSAR technologies were suitable for monitoring surface deformation in areas with elevations below 1000 meters in the study area.The SBAS-InSAR and DS-InSAR technologies had relatively good applicability in areas with elevations above 1000 meters.(4)In view of the lack of quantitative evaluation of the accuracy of potential geological hazard monitoring results based on InSAR technologies,a study was conducted on the accuracy evaluation of potential geological hazard monitoring by integrating multi-source remote sensing,and the characteristics of deformation influencing factors such as slope,vegetation coverage,and rainfall were analyzed.Thirteen potential geological hazard sites identified and monitored through multi-source remote sensing based on InSAR technologies were selected for comparative analysis research with the known hazard points,field verifications,and drone images in this thesis.The experimental research results of this thesis indicated that: 1)In the field verifications of the 13 potential geological hazard points,9 were found to have deformation,with a deformation monitoring accuracy of 69.23%.2)Among the 13 potential geological hazards,11 were new added,and 7 had been confirmed as new ones through field verifications.Thus,the accuracy rate of identifying new hazards is 63.64%.3)The risk level standard of potential geological hazard was obtained through analysis,and based on this standard,some typical potential geological hazards monitored were analyzed;The potential geological hazard sites were mainly distributed in the elevation range of 1 000-3 500 m,with a slope range of 20°-40°,vegetation coverage mainly less than 0.40,and the deformation activities of the potential geological hazards in the study area of this thesis were greatly affected by the heavy rainfall during the flood season. |
