The 3rd Badong International Geohazards Symposium (BIGS2021)

7 / 2021-10-10 15:49:24

Monitoring Surface Deformation with SBAS-InSAR Technique and Sentinel-1A images in Fugong County, Yunan Province

SBAS-InSAR,PS-InSAR,deformation,Sentinel-1A

In this study, the surface deformation of Fugong County from 2019 to 2020, was monitored with the Small Baseline Subset Interferometric Synthetic Aperture radar (SBAS-InSAR) technique and 54 Sentinel-1A images. In the SBAS-InSAR technique, times series SAR images were divided into a number of interference pair subsets based on time and space baseline thresholds, to reduce the impact of spatiotemporal decoherence on the SAR image interferogram. The comparison between PS-InSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) and SBAS-InSAR shows, PS targets are mainly distributed around buildings; while SBAS targets has wider range and higher density. The SBAS-InSAR detection results indicate the surface deformation of the county is mainly distributed in the valley of Nujiang River, whose mean velocity is about 3.98mm/year with a 14.18mm standard Deviation. Further analysis shows landform (elevation, slope, aspects), the distance to rivers, and human activity have significant influences on slope stability. Most deformation is located in the elevation range of 1000m-1300m above sea level, the slope range below 45 °, and the aspect of east and west. The areas close to rivers are prone to deform due to river erosion, while those far from rivers is more stable. It is also found 80% of deformation points are located near roads, which suggest that anthropological activities also have important impacts on slope stability. In conclusion, SBAS-InSAR could effectively improve the range and density of surface deformation monitoring in complex mountainous areas, compared with ground investigation and PS-InSAR, by using time series analysis and the “multi-master image” strategy.