PS-InSAR Analysis of Collapsed Dam and Extraction of Flood Inundation Areas in Laos Using Sentinel-1 SAR Images

Interferometric Synthetic Aperture Radar (InSAR) technique can potentially measure millimetre-scale changes in deformation by two or more SAR images. In this paper, thirty Sentinel-1 SAR images were processed with Persistent Scatterer InSAR (PS-InSAR) method over the collapsed dam in Laos to measure its deformation in the last year before the collapse. Then the deformation map of the dam is achieved. The map show that unusual subsidence occurred in the final two months prior to the collapse. Several feature points distributed near the collapse of the dam were analyzed. The maximum accumulated subsidence exceeded -20 mm in the last year. Our results indicate that PS-InSAR technology for deformation monitoring of dams can be used as an early warning method to prevent other similar accidents. Furthermore, we extracted the flood inundation map from two Sentinel-1 images. It can play a role in post-disaster relief work.