Research On Large Gradient Deformation Monitoring Technique Based On SAR And Optical Remote Sensing Data

Geological disasters occur frequently in southwest China,and high speed mass displacement often causes more serious disasters and losses.Remote sensing technology has become an indispensable detection means for large-scale and regional geological disaster monitoring and investigation.Remote sensing technologies such as In SAR technology and offset tracking can be used to analyze the breeding mechanism of disasters according to multi-temporal data,and the process before and after disasters can be recovered and tracked qualitatively or quantitatively,and a variety of natural disasters can be economically and efficiently monitored.However,the monitoring application of remote sensing technology also has limitations.In SAR technology is easily affected by time decorrelation,and the monitoring accuracy of offset technology is low.Therefore,the comprehensive use of multiple remote sensing monitoring technologies is the most effective means to monitor a large scale glacier or landslide.Based on SAR image and optical image,In SAR technology,offset tracking technology and joint monitoring method are comprehensively used to monitor and analyze the motions of glaciers and landslides.The main research contents and achievements include the following two aspects:(1)A large glacier in Shishapangma peak region of Tibet was selected as the research area.The Sentinel-1 and Landsat8 heterogeneous data sources from January 2019 to January2021 were used to estimate the offset,and then the optimal estimation of the three-dimensional deformation rate of the glacier was obtained based on the variance component estimation joint model.The results show that the maximum deformation rates of the glacier in the east-west direction,North-South direction and vertical direction are85mm/day,126mm/day and 88mm/day,respectively.Compared with the calculation results of optical images in the same period,the accuracy of the model increased by 41% in the east-west direction and 36% in the North-South direction on average.Moreover,the combined calculation of the flow velocity of the surface moraine glacier was more consistent with the vector boundary of the glacier cataloging data.Two image pairs with more data were selected to verify the feasibility of the combined solution model to obtain the temporal glacier velocity.The characteristics of glacier velocity were analyzed based on slope and air temperature data.At the same time,this model can improve the temporal resolution of monitoring results and obtain more information about glacier characteristics.The research results of this paper can provide a reference for obtaining massive three-dimensional displacement of glaciers by combining multi-source remote sensing data,and provide support for the identification and early warning of glacier disasters.(2)Jinsha River Baige Landslide is selected as a typical landslide.Sentinel-1,ALOS-2and Landsat8 data are comprehensively used in this paper.Based on the combination of SBAS-In SAR technique,SAR offset and optical offset technique,the temporal deformation results and deformation characteristics of Baige landslide before sliding,first sliding,second sliding and post-sliding were obtained.The results show that,before sliding,the cumulative deformation of optical offset from November 2014 to March 29,2018 can reach 40 m,and the deformation area is in the middle of the landslide.The deformation results of the SAR offset in May and July 2018 can reach 6.4m,and the deformation area is also in the middle of the landslide.From January 12,2018 to October 3,2018,the average annual In SAR deformation rate of the landslide can reach-143mm/y,and the top of the landslide has obvious deformation.The first slip: the LOS deformation reached a maximum of 48 mm,and deformation occurred at the trailing edge and left upper side of the landslide.The second sliding: the deformation reached 72 mm,and settlement occurred on both sides of the trailing edge after sliding.Post-slip: From November 8,2018 to November 28,2021,the post-slip deformation rate of Baige landslide reached-140mm/y,and the deformation range on the upper left side of the landslide expanded and extended.The research results restore the whole sliding process of a large number of grade-displacement landslides and provide a reference for landslide warning and monitoring research.