Preliminary analysis of a LiDAR-based landslide inventory in the area of Samobor, Croatia

The paper presents an analysis of the LiDAR-based landslide inventory for the area near Samobor, in northwestern Croatia with two main objectives: i) to define the geological units (obtained from Basic Geological Map of Croatia) most susceptible to landslides, and ii) to analyse the limitations of the Basic Geological Map and its applicability in landslide susceptibility map design. Within the study area of 63.8 km2, 874 landslide polygons were manually outlined, covering an area of 2.15 km2. The landslide outline confidence level, landslide index and the relief energy map were used to analyse the landslide susceptibility of a particular geological unit. By that, units in the same state of stress, i.e., in the same relief energy group were compared. This preliminary analysis has shown that the geological units Pl,Q, M31,2, and 1M31 are the most susceptible to landslides and that older geological units, Pc and K1,2, are also prone to landslides. Still, landslides within those older units can be considered as old and inactive. As for the limitations of the Basic Geological Map of Croatia, three things emerged, namely scale, the geological unit defining approach, and the neglect of regolith. Despite the limitations presented, the usability of the Basic Geological Map of Croatia in the development of small-scale landslide susceptibility maps is emphasized. However, instructions that should attribute engineering geological features to the geological units outlined in the Basic Geological Map should be prepared in the near future.