The impact of mass movements on alpine trails and huts assessed by EO data

The large value of the alpine infrastructure of trails and huts for the society lies in its essential role for summer tourism in the Alps. About 2.5 million hiking tourists visit Austria every year and an additional 2.5 million locals choose hiking as a recreational activity. The Alpine associations maintain the hiking infrastructure of trails and huts and thereby enable the access to the mountainous terrain free of charge for the public. A big challenge for trail and hut management and maintenance are mass movements like shallow landslides, debris flows and rockfalls. They can cause significant damages to alpine infrastructure and may block the access to certain mountain areas for weeks or even months. Such damages require repair and increased maintenance activity or even rerouting of trails. Climate change will make the problem more pressing as more frequent and severe mass movements are expected. Consequently, alpine infrastructure management has an increased demand for consistent and appropriate information on mass movements.
A promising opportunity to support maintenance activities arises through the new generations of Earth observation (EO) satellites of the European Copernicus programme. They allow comprehensive coverage and high frequency of data acquisition with a sufficiently high resolution to detect mass movements with an impact on alpine infrastructure.
Therefore, the project MontEO (The impact of mass movements on alpine trails and huts assessed by EO data) investigates the opportunities for EO-based mass movement mapping and hazard impact assessment for alpine infrastructure. We analyse the potential benefit for trail and hut keepers and the value that an improved quality of the alpine infrastructure has for the society. We develop a multi-scale approach and combine optical and synthetic aperture radar (SAR) satellite data (Sentinel-1/2, Pléiades or similar) to comprehensively map mass movements and to detect mass movement hotspots. Further, we integrate the EO-based mapping results with ancillary data for landslide susceptibility mapping, and for modelling and simulating rockfalls and debris flows. Finally, we analyse the network of trails and huts in relation to the obtained mass movement information and thereby assess the impact of mass movements on alpine infrastructure, i.e. identify the trails and huts that are (potentially) impacted by mass movements.
We demonstrate the concept and methods for three study areas in the Austrian Alps: Großarl and Kleinarl Valley in Salzburg, Karwendel in Tyrol, and Salzkammergut in Upper Austria. For these areas, we will create EO-based mass movement inventory maps, hotspot maps, and hazard impact maps. We validate our results in close collaboration with the users and analyse their usefulness for alpine infrastructure maintenance and management. The outcomes of MontEO will contribute to improved maintenance efficiency and will lead to a safer alpine infrastructure with an increased value for the tourism industry.