Identification of Landslides as Debris Flow Sources Using a Multi-model Approach Based on a Field Survey—Koroška Bela, Slovenia

Abstract

The landslide as a debris flow source identification is an important but often complex step in debris flow hazard assessment. Landslides are an important source of debris flows and this paper presents a multi-model approach of identification. The village of Koroška Bela in NW Slovenia has a history of debris flows and active landslides in the watershed of the Bela torrent, which presents a sediment source for potential debris flows in the future. Two models were applied for landslide identification in the watershed. A detailed field survey was carried out for model results validation. A GIS-based landslide susceptibility model was applied to identify areas susceptible to landslides and the LS Rapid triggering model was applied also to identify landslides and simulate the triggering phase. The study results show good agreement of the field survey and the models, particularly considering the completely different origin of both models and their development. These results show the possibility of applying numerical models to identify landslide sources and encourage their implementation in debris flow hazard assessment. But as with all models, a high level of expert knowledge and users' experience is required to get useful, and what is more, reliable results.