Original paper

Identification and Modelling in Flysch Areas of the European Alpine Foreland

Neuhäuser, Bettina; Terhorst, Birgit; Damm, Bodo


The objective of the present study is landslide identification and susceptibility assessment in the Flysch zone of the Vienna Forest in Lower Austria. Landslide susceptibility, expressed as the possibility of a landslide occurring in a certain area, is determined on the basis of the relationship between specific geofactors and landslides that already occurred. Thus, identification and mapping of landslides are essential for modelling in the study area. A newly generated landslide inventory comprises historical as well as present-day databases and maps, and includes 600 mass movements. This data set is focused on spatial distribution of naturally triggered landslide processes, which represent the predominant type of mass movements in the study area. The data are analysed with regard to geological environment, geomorphological characteristics, and chronological distribution. Besides the inventory, controlling geofactors, which create the predisposition for slope failure, need to be identified and mapped. In this context, the detailed knowledge of geomorphological processes, gained by field investigations, is an indispensable precondition. Finally, controlling factors are derived from topographical and geological data, land cover data, as well as digital elevation data. By means of the landslide inventory and the derived controlling geofactors, a comprehensive susceptibility map is compiled by the Weights-of-evidence method. The results prove that the disposition model allows delineating landslide prone areas and provides new information on the relation of landslide processes to specific controlling geofactors. In particular, the model depicts the relevance of clay shale zones within the Flysch formations as controlling geofactor. Furthermore, it is proved that the distribution of landslides is closely connected to fault systems and nappe boundaries. An increased frequency of landslides is detected in proximity to drainage lines. In association with heavy rainfall, torrential conditions can occur in streams and creeks and can foster landslide proneness in adjacent hillslopes in the study area. In general, landslide susceptibility is enhanced on N-W facing slopes, which are exposed to the prevailing direction of advective rainfall in the study area. The latter geofactors indicate the significance of meteorological and hydrological conditions, in particular of precipitation and surface runoff for the occurrence of landslides. Model assessment and validation is carried out, indicating a sound predictive capability of the model. Latest data on soil-mechanics and sedimentology, derived from field and laboratory investigations are collected and prepared for subsequent use in physically-based GIS modelling, which complements the present work.


landslide identificationlandslide susceptibilitygis modellingweights-of-evidenceflysch zonevienna forest