Comparing landslide mapping from DTM satellite derived data and field based studies of Loess sediments in Western China

This paper focuses on experiences gained by creating a landslide inventory map for a study area of approx. 850 km2 near the city of Tianshui in Gansu province, Western China. The study area consists of a Loess landscape that is strongly anthropogenic transformed by terraced agriculture and is interspersed by mainly earthquake triggered landslides. Two different approaches were performed to establish an inventory map of landslides: Mapping landslides from field based studies and mapping landslides from a DTM derived from a Pléiades satellite image pair. Pléiades images offer a panchromatic ground sampling distance of 0.5 m which enabled us to create a Digital Terrain Model (DTM) with a resolution of 1.0 m. The methodologies of these two landslide mapping approaches are presented and respective results are compared showing advantages and disadvantages of each approach. One of the main results of the project was to demonstrate the applicability and the effectiveness of DTM mapping in Loess sediments of Western China. In comparison to field mapping, the DTM inventory is at least of equal quality as the field mapped inventory because of its consistency and completeness. DTM mapping is also a much more cost efficient tool, especially when looking at mapping larger areas in remote locations in Western China, as well as those areas which are difficult to access.