Study On The Sensitive Characteristics Of Observational Geometry Parameters For InSAR Landslide Deformation Monitoring

Landslide is a kind of natural geological event,which has the characteristics of wide distribution,strong suddenness,high frequency of occurrence,and great destructive power.With the continuous growth of population and the intensification of human and natural activities,landslide disasters have become one of the most serious natural disasters threatening the survival and development of human beings,not only causing huge losses to people’s lives and properties,but also seriously threatening the public safety of society.The interferometric synthetic aperture radar(In SAR)technology,which has been developed continuously in recent years,has broken the limitation of traditional monitoring methods and realized all-day,all-weather and wide-range earth observation,which is widely used in landslide research.However,due to the unique side-view imaging mode of radar satellites,geometric distortions such as shadowing,layover and foreshortening are easily produced when imaging landslides.In addition,the deformation or deformation rate obtained from In SAR deformation monitoring is the deformation in the radar line of sight direction,which is the projection of the real landslide deformation in the LOS direction,and in most cases,the direction of the real landslide deformation is not consistent with the LOS direction,so In SAR sensitive Characteristics of landslide deformation monitoring needs to be studied.Aiming at this problem,the sensitive characteristics of the observed geometric parameters of In SAR for monitoring landslide deformation are studied in this paper.Considering the influence of incident angle,slope aspect and geometric distortion,a sensitivity factor is constructed,and takes the eastern section of Wenma Highway as the research object and conducts analysis and verification.The main research works and conclusions are as follows:(1)Analysis of landslide visibility in SAR images.This paper analyzes the visibility of landslide in SAR images by simulating the change of R-index at different radar incidence angles,slopes and aspects,and the results show that the R-index of the ascending and descending tracks are consistent with the distribution of radar incidence angle and slope,while the difference lies in the distribution with the change of aspect angle.The areas with better visibility of the ascending rail are all located in the(0,167)∪(347,360)aspect interval.In this interval,the larger the angle of incidence,the better the visibility,but when the angle of incidence exceeds the residual angle of the slope,shadowing will appear.The larger the slope angle,the better the visibility,but shadowsing will appear when the slope angle exceeds the residual angle of the incidence angle.The area with better visibility of the descending track is located in the(0,13)∪(193,360)aspect interval,and the change of visibility with the incidence angle and slope angle is consistent with the ascending track.(2)Sensitive characteristics of landslide deformation monitoring.In this paper,the Sensitive characteristics factors are constructed by considering the effects of radar incidence angle,slope and slope direction,and geometric distortion,and the variation of sensitive characteristics factors with different radar incidence angles,slopes and aspects is simulated and analyzed.The results show that the sensitive characteristics factor of ascending and descending tracks are consistent with the distribution of radar incidence angle and slope,while the difference lies in the distribution with the change of aspect angle.The sensitive characteristics factor increases with increasing incidence angle,but the sensitive characteristics factor decreases to 0 when the slope angle exceeds the residual angle of the incidence angle.The area of higher sensitive characteristics factor of the ascending track is located in the(0,167)∪(347,360)aspect interval,and the sensitive characteristics factor increases with the slope angle.The area with higher sensitive characteristics factor to descending track is located in the(0,13)∪(193,360)aspect interval,and the variation of sensitivity characteristics factor with the incidence angle and slope angle is consistent with the ascending track.(3)Monitoring and sensitivity characteristics factor analysis of landslide hazard in the eastern section of Wenma Highway.In this paper,a total of 12 landslide hazards in the eastern section of Wenma Highway were identified and monitored by Stacking-In SAR technology and SBAS-In SAR technology,and the sensitivity characteristics factors of the andslide hazards were analyzed and verified,and the results showed that the higher the sensitivity characteristics factor,the easier the landslide is to be monitored,on the other hand,if the sensitivity characteristics factor is low but still monitored,it means that the landslide has a large deformation rate.If the sensitivity characteristics factor is low and the deformation rate is large but not monitored,indicating that its deformation direction is close to the flight direction of the radar satellite.It is proved that the sensitivity characteristics factor can provide effective a priori information for landslide monitoring.