Use of multi-source remote sensing images to describe the sudden Shanshucao landslide in the Three Gorges Reservoir, China

The primary objective of this research is to better understand the movement characteristics and patterns of a sudden landslide that occurred in the Three Gorges Reservoir, China (the Sept. 2, 2014 Shanshucao landslide) by using three periods of multi-source remote sensing images in combination with a field survey. A georeferenced, aerophotographic orthomosaic and corresponding 1:2000 topographic map of the pre-landslide area was referenced to rectify the micro-unmanned aerial vehicle (UAV) based orthomosaic, digital surface model (DSM) and Google Earth satellite image of the post-landslide area. By using orthomosaics of the post-landslide area, especially the very high spatial resolution micro-UAV based orthomosaic, the landslide boundaries were accurately delineated. By comparing the images of the area both pre- and post-landslide, three landslide subzones were identified, and two boundaries between the three subareas were divided more precisely than in previous studies. Based on the digital elevation model (DEM) of the pre-landslide area and DSM of the post-landslide area, the change in altitude and volume of the landslide were quantified. Then, the movement pattern of the landslide was proposed. The results showed the rocky, southern sliding part was the main sliding zone with the longest distance and deepest sliding surface, and the northern soil mass did not experience any overall movement. However, loose soil mass collapse and features of counterclockwise rotation were observed under the traction of the rocky, southern sliding part. Additionally, more accurate knowledge has been obtained including the location of the original lateral boundary, shear outlet altitudes, and main triggering factors of the rocky sliding mass. This study has demonstrated that the use of multi-source remote sensing images, which include both pre- and post-landslide images, can effectively describe the characteristics, patterns, and even the mechanism of a sudden landslide.