Combining pre-event optical and post-event polarimetric SAR data for rapid landslide mapping

Abstract

Fast crisis response, i.e., the support of rescue and humanitarian operations, requires quick information about the extent of the affected area and type and grade of damage. Most synthetic aperture radar (SAR) data-based landslide detection approaches reported in the literature use change detection techniques, requiring very high resolution (VHR) SAR imagery acquired shortly before the landslide event. However, such pre-event data is commonly not available. Modern VHR SAR missions, e.g., TerraSAR-X, Radarsat-2 or COSMO-SkyMed, do not systematically cover the entire world, due to limitations in onboard disk space and downlink transmission rates. Therefore, this paper presents a fast and transferable methodology for rapid landslide mapping, based on change detection between pre-event optical imagery and the polarimetric entropy derived from post-event VHR polarimetric SAR data. Pre-event information is derived from high resolution optical imagery of Sentinel-2 or Landsat-8, which are freely available and systematically acquired over the entire Earth’s landmass. The results of the landslide mapping are refined by slope information from a digital elevation model generated from bi-static TanDEM-X imagery. The application of the methodology is demonstrated at two case studies: A mining waste earthflow near Bolshaya Talda, Russia and a rotational slide near Charleston, West Virginia, USA.