9 / 2021-10-18 05:11:24

Satellite-Based Assessment of Rainfall-Triggered Enshi Landslide Hazard

Enshi landslide; InSAR; Hazard assessment

Landslide can endanger people and infrastructure, especially in densely populated mountainous regions. The landslide occurred in the early morning of 21 July 2020 in the Mazhe village, Enshi city, Hubei Province, China. In this paper, we apply PSI, SBAS and EMI three approaches, Sentinel-1 and TerraSAR-X radar data, Planet and Sentinel-2 optical data, and Tandem-X data to study Enshi landslide. To derive a precise DEM in this case low coherence mountainous areas, we generated a precise TanDEM-X DEM by comparing the two pre-event and two post-event Tandem-X DEM using a re-flattening iterative method. The lost mass volume of the Enshi landslide was estimated to be 260 million m³, which is consistent with the report result in a previous researcher’s paper. To assess the potential of weather-independent radar satellites, we compared surface displacement mapping results from high-resolution TerraSAR-X stripmap images and medium-resolution Sentinel-1 interferometric wide-swath images for Enshi Landslide. The TerraSAR-X results were also compared to available mapping results from high-resolution Planet and medium-resolution Sentinel-2 optical satellite images. We found that landslide outlines and time-series results from TerraSAR-X and Sentinel-1 agree well with each other. Moreover, we address the difference and similarities between the PSI, SBAS and EMI multitemporal InSAR methods for displacement studies in decoherence areas. We found that EMI is better than the other two methods in decoherence areas. The time-series results from Sentinel-1 before-failure show that an early warning of the imminent failure could have been given. The time-series results from Sentinel-1 and TerraSAR-X after-failure show that the west part of the Enshi landslide is still active and exhibiting a maximum displacement rate of 7 cm/year, 5 months after-failure.