Geological Hazards Detection And Deformation Analysis In Mountainous Areas Of Guizhou Based On Space-borne InSAR Technology

In the past three decades,Interferometric Synthetic Aperture Radar technology has been widely used in many fields of geological disaster monitoring with its advantages of all day,all weather,high precision and large scale.In SAR can detect small ground deformation,which makes it an important technical method for early detection and early warning of geological hazards.The frequent occurrence of geological hazards in China has brought great losses to people's lives and property safety,natural environment and social economy.Especially in the southwestern mountainous areas,the geological landscape is complex,the terrain is highly undulating,the vegetation cover is dense,and most of the geological hazards occurring are located in high and hidden areas,which are difficult to be detected by conventional surface monitoring technology,In SAR technology undoubtedly become an important tool for geological hazards detection in these areas.Geological hazards are widely distributed in the southwestern mountainous region represented by Guizhou,so it is necessary to carry out geological hazard potential investigation on a large scale.There have been many applications of deformation detection and analysis using In SAR technology,but it is generally difficult to meet the demand for long-term,large-scale,rapid and accurate monitoring.In addition,external topographic data are required to assist In SAR processing and analysis in mountainous areas,and the influence of DEM errors on In SAR deformation monitoring results needs to be studied urgently.Therefore,in this thesis,the following research contents are carried out for the application of In SAR technology in large-scale geological hazard potential detection in mountainous areas and the influence of topographic errors on In SAR deformation detection and analysis.(1)Aiming at the actual demand of geological hazard potential investigation in the mountainous area of southwestern Guizhou,this thesis proposes the potential hazard detection strategy of using Differential In SAR for the preliminary large-scale rapid census and detailed investigation by Time-series In SAR analysis in key areas.Through the comparison of a series of deformation results,the advantages and disadvantages of Differential In SAR and Time-series In SAR methods in terms of processing efficiency,resistance to error interference and applicable deformation gradient levels are analyzed,the complementarity of the two methods is clarified,and the technical route of combining D-In SAR and time series In SAR is verified to be highly efficient and accurate in the large-scale geological hazard detection.(2)External DEM data are usually introduced in In SAR processing to simulate and remove topographic phase,but the DEM data commonly used to remove topographic phases have low accuracy and were acquired many years ago,which differ from the real surface morphology,thus leading to topographic error phase.To investigate the influence of DEM errors on In SAR,this thesis used Li DAR DEM,AW3D30 and SRTM-3 as external DEM data to carry out StaMPS-SBAS In SAR processing in the mountainous region of southwestern Guizhou,compared the D-In SAR phase,PS points selection,DEM error estimation,deformation rate and deformation sequence results obtained by the three DEMs,and analyzed the influence of external DEM accuracy on the In SAR results,which is an important reference for the engineering application of In SAR technology.