Identification Of Potential Wide-Area Creeping Geohazards In Mountainous Areas Using TS-InSAR Technology

The Creep Geological Hazard Potential is a potential geological hazard with signs of slowly creeping,such as creeping landslides,creeping sources of debris flow,deforming slope bodies,dangerous rock bodies,etc.,which are prone to rapid movement to form catastrophic events when influenced by induced factors such as rainfall,earthquakes,freezing and thawing,and human engineering activities.Creep characteristics(creep rate,creep range,etc.)can characterize the current situation of creep geological hazards,and if creep characteristics before the occurrence of damage can be effectively identified,it will help the early warning and prevention of creep geological hazards and avoid the loss of life and property,which is of great significance in disaster prevention and mitigation work.TS-InSAR technology has the ability to monitor the continuous slow deformation of the wide-area ground surface,which combines the advantages of wide coverage,strong penetration ability,no restriction of accessibility,high monitoring accuracy and low cost,etc.It has greater advantages in the identification of creep features,and is theoretically the preferred technology for the identification of wide-area creep geohazards in mountainous areas.However,there are still many challenges in the actual application,such as the processing of large amount of wide-area SAR data,the optimal selection of interferometric image pairs,the effective extraction and spatio-temporal feature analysis of creeping geohazards potential hazards,etc.are faced with problems.This makes the existing conventional TS-InSAR technology and related methods difficult to be applied in the identification of wide-area creeping geohazards in mountainous areas,and still needs to be studied in depth.For this reason,this paper takes some mountainous areas in southwest China as the research area,and explores some useful methods of TS-InSAR technology in the detection,extraction,monitoring and analysis of creeping geological hazards in mountainous areas based on Hy P3 In SAR online service data and Sentinel-1A SLC data,so as to effectively identify and analyze creeping geological hazards.The specific research content,and conclusions are as follows.(1)To address the problem that the interferometric coherence of SAR images in mountainous areas varies from month to month,and the traditional use of customized coherence coefficients or short spatial and temporal baseline thresholds can easily lead to disconnected,redundant or missing interferometric baselines,this study uses the segmented average coherence coefficient threshold method to optimize the selection of interferometric image pairs taking into account the differences in coherence coefficients from month to month,which can improve the overall coherence,reduce the redundancy of interferometric pairs in high coherence months,increase the number of interferometric pairs in low coherence months,and obtain a more robust interferometric baseline network,and the method has good applicability in the experimental area of this paper.(2)In response to the problem that traditional TS-InSAR data processing requires a large amount of computational resources and is difficult to be applied in wide-area creeping geohazard identification,a TS-InSAR processing strategy combining Hy P3 In SAR online service data and Sentinel-1A SLC data is proposed,with Hy P3 In SAR online service data used for wide-area range of mountainous areas The Hy P3 In SAR online service data are used for surface deformation detection over a wide area in mountainous regions,and the Sentinel-1A SLC data are used for further monitoring of the extracted small-area potential hazard areas.The processing strategy takes into account the advantages of wide-area detection of In SAR online service data set and the advantages of preserving the original resolution of SAR SLC data,and the data and software used can be free and open-source,with low hardware requirements,which can be easily applied in wide-area geohazard identification work.(3)The effective extraction of geological hazard potential areas in a wide area and the spatial and temporal characteristics analysis of typical geological hazard potential areas were carried out,combining multi-threshold segmentation and aggregation point(polygon)analysis methods to effectively extract and map geological hazard potential areas with creep anomalies from the surface deformation results detected by TS-InSAR for ascending and descending tracks in the study area.Based on the spatio-temporal cube principle,a creep spatio-temporal cube model was constructed to view the historical state of creep data and track the spatio-temporal changes,and the emerging spatio-temporal hotspot analysis method was used to analyze the spatio-temporal characteristics of creep,taking the two extracted typical geological hazard potential areas of Lannigou and Baobao Village as examples.