Unravelling the complex dynamic of slow-moving landslides in the Flysch zone region, Lower Austria. A case study of the Hofermühle catchment.

Abstract

Slow-moving landslides are complex processes that represent a significant challenge for landslide dynamic analysis and disaster risk reduction. In some cases, they have been considered as early signals of potential destructive events as they can accelerate under specific climatic conditions, causing significant damage.  However, slow-moving landslides have been constantly neglected as the require significant time, human resources, and specific numerical models to assess their non-uniformity. Considering the existing gaps and the lack of data of slow-moving landslides in Austria, a long-term monitoring project has been carried out by the ENGAGE group of the University of Vienna. Several investigation techniques for hydro-geo monitoring have been installed in Lower Austria for multi-temporal landslide investigation in several landslides, using them as living laboratories. Therefore, the present study aims to integrate the valuable hydro-mechanical data to bring light on potential acceleration conditions of slow-moving landslides, frequency and intensity relationships and cascading hazards initiated from within the slow-moving landslide mass.  The geographical and geological conditions of the province of Lower Austria place it as a very susceptible region to the occurrence of landslides. The predominant geology correspond to the units of the Flysch Zone and the Klippen Zone, which are mechanically weak units composed by intercalation of limestones and deeply weathered materials. These conditions, along with the hydrological conditions, land use changes and other anthropogenic impacts contribute to the instability of the region. Consequently, in order to understand landslide processes and mechanisms, we attempt to integrate the hydro-mechanical data compiled from the monitoring sites to model a complex event triggered in 2013, in the Hofermühle catchment, district of Waidhofen an der Ybbs, in order to improve our understanding of landslide conditioning factors and triggering mechanisms of potential cascading hazards in the region.