Research On The Application Of PS-InSAR Based On Sentinel-1 Data In Monitoring Of Baige Landslide In Jinsha River

At 22:06 on October 10,2018,a large-scale high-level landslide occurred in Baige Village,Boluo Township,Jiangda County,Tibet Autonomous Region,lasting for about 120s.Baige landslide has been the most serious river-blocking event in the main stream of the Jinsha River since December 22,1935,when the Shabagou landslide in Qiaojia County,Yunnan Province river-blocking happened.It is extremely destructive,and the destruction of infrastructure such as villages,farmland,roads,and bridges downstream of the landslide is also very serious.Taking Baige landslide as the research object,Making use of technology PS-InSAR to extract deformation results of the pre-landslide area and to analyze the characteristics and trend of the time series deformation movement.Baige District of the Jinsha River is located in the southwestern mountainous area of China,the terrain is complex and variable and the geological structure is fragile,it is a high incidence area of landslide disaster.Traditional methods of landslide survey and monitoring are difficult and have to cost huge manpower and financial resources.This paper uses radar remote sensing to monitor landslide.This passage first analyzes geologic environmental condition according to the rock lithology,geological structure and other factors in the landslide area,and to analyze the geological characteristics and forming reasons for the reason of landslide happening.The formation of landslide is mainly affected by fault structure,lithology of rock stratum and other factors.Thereinto,the landslide mountain weathering is serious,historical earthquakes also have some potential effects on landslide areas.1.Using the Radar remote sensing to quickly extract the range of Baige landslide.Baige landslide causes large area destruction of surface vegetation,and then changes the earth's surface roughness,complex dielectric constant and other characteristic information,in the Radar images before and after the landslide,the backscattering intensity is obviously different in the area with severe surface damage compared with other areas,and makes the SAR image easy to recognize the geometric morphological characteristics such as the back wall and the leading edge of the landslide body.Using the two methods that are the same polarization cross-polarization ratio method and interferometric SAR coherence map to extract the landslide scope at the same time,compared with the optical image of the landslide area after the disaster,the location of the extracted landslide is the same and the contour range of the landslide is basically the same.2.Using the technology PS-InSAR to monitor the Baige District and to obtain the regional deformation results before the occurrence of landslide and to analyze variation trend.This passage obtain 35 scenes Sentinel-1A satellite image data from March 2017 to May 2018,and make use of technology PS-InSAR obtain results of temporal deformation in landslide area.The results show that before June 2017,there was no significant surface deformation in the landslide area as a whole.After June 2017,the whole region presented a subsidence trend,the subsidence is not obvious near the ridge and outside the landslide area,the exposed rock in the middle and the lower part of the main slip zone show obvious deformation,until September 2017,the accumulated deformation began to decrease,but the subsidence deformation was still the main deformation.After in November 2017,the exposed rocks and fissure in the main slide area presented obvious uplift deformation,the subsidence variable in the traction area also increases gradually,while the surface deformation in the area beyond the scope of landslide is not obvious.3.Analyzing the different characteristic points of the time-series deformation information along the profile of the landslide direction and the traction area,the main slip area and the resistance slip area,combining with the process of landslide formation,the deformation characteristics of different feature points are analyzed spatially and temporally obtaining the deformation rate along the section line along the landslide direction.The traction area presents a tendency of subsidence as a whole,and there is a brief uplift stage in the whole process of subsidence.Thereinto,the feature points continued to sink before the landslide.In the main sliding area in the middle of the mountain,the overall trend is upward.Affected by the subsidence change in the traction zone and the extrusion in the friction-slip zone,there is a short subsidence stage with lag in the whole uplift process.The feature points,especially the fracture area,were obviously uplifted before the landslide.Along the section along the landslide direction,the subsidence rate in the traction area far away from the ridge gradually decreases,and the lifting speed first increases and then decreases in the main slide area,until the deformation rate in the resistance slide area is close to 0.The rate of sedimentation of the significant area is gradually increasing,and the average deformation rate from the end of 2017 to the middle of 2018 can reach-6 mm.