Stuyd On The Landslide Information Extraction In Bailongjiang Basin Using SBAS Technique

Bai Longjiang Basin is one of regions which has the most frequent geological disasters (debris flow, landslide, et al.) in China. Time-Series InSAR can eliminate geometric and temporal de-correlations and effects of atmospheric phase screen compared with D-InSAR. Therefore, surface deformation information from the former can achieve millimeter level. Taking the estuary to Wudu region as the research area, this study used ENVISAT ASAR data and Small Baseline Subsets (SBAS) technique to monitor the surface deformation of the area. Then this study analyzed the visibility of study area based on DEM data and the acquisition geometry of the radar. On the other hand, we studied land cover types of the CTs. Based on CTs and annual average strain rate derived from SBAS, the potential landslides are extracted. Finally, this study carried on the analysis to two typical landslides and several conclusions are drawn as follows:(1)Using Small Baseline Subsets (SBAS) technique to monitor the surface deformation in 2008.5 to 2010.10, this study derived an annual average strain rate of-2.87mm/year. The visible area derived from RI threshold of 0 and 0.4 has a better result.visibility map derived from RI-based method is much more accurate than that from terrain-based method.85.05% of the CTs are located in the visible area,16.06% are located in the area of visual with difficulty, and the rest in the not visible area. In addition, there are the most CTs on both sides of the valley where have sparse vegetation and severe erosion, the 67.23% of the area included CTs is acceptable,the 96.83% of CTs from SBAS procedure reliable.(2)The study derived 14 blue hotspots and 22 red hotspots of significant movement according to CTs clustering and then determined 9 landslides,4 of them are new landslides. The two typical creep landslides are both distributed inside the concave slope of fault zones where with many soft rocks. Central landslide slip velocity is the fastest, both sides of the area is relatively slow. In addition, front moving speed is faster than trailing edge.