Assessment of landslide age, landslide persistence and human impact using airborne laser scanning digital terrain models

Abstract

Bell, R., Petschko, H., Röhrs, M. and Dix, A. Assessment of landslide age, landslide persistence and human impact using airborne laser scanning digital terrain models. Geografiska Annaler: Series A, Physical Geography, 94, 135–156. doi:10.1111/j.1468‐0459.2012.00454.x

ABSTRACT

Landslides occur worldwide and contribute significantly to sediment budgets as well as to landform evolution. Furthermore, they pose hazards and risks to people and their goods. To assess the role of landslides, information on their age or persistence (i.e. the length of time the morphological characteristics of a landslide remain recognizable in the terrain) is essential. In this study, the potential of airborne laser scanning digital terrain models (ALS DTMs) is analysed for estimating landslide age, landslide persistence and human impact. Therefore, landslides in two study areas, Swabian Alb in Germany and Lower Austria in Austria, are mapped from hillshades of ALS DTMs and combined with historical information on landslide occurrence. It is tested whether the modification of the geomorphological features of landslides can be used to assess landslide age. In the Swabian Alb older landslides might show fresher features than younger ones because of different degrees of human impact, natural erosion and different histories of landslide reactivation. Estimated persistence times range between 27 and 320 years but are minimum values only. In Lower Austria four landslides show estimated minimum persistence times between 4 and 28 years. In Lower Austria 27 landslides disappeared in less than 7 years after occurrence mainly because of planation by farmers. The results show no clear trend in landslide persistence, neither regarding landslide magnitude, nor regarding land use. However, it is evident that human impact plays a major role in landslide persistence.

Key words:

• airborne LiDAR
• human activity
• landslide persistence
• Lower Austria
• orthophoto
• Swabian Alb

Acknowledgements

Research was carried out within the following three projects: InterRISK (Interdisciplinary risk analysis and evaluation of recent landslides in the Swabian Alb), ILEWS (Integrative landslide early‐warning systems) and MoNOE (Method development for landslide susceptibility modelling in Lower Austria). We highly appreciate the financial support of the German Research Foundation (DFG) for the project InterRISK (GL 347/3), of the German Ministry for Education and Research (BMBF) for the project ILEWS and of the Provincial Government of Lower Austria for the project MoNOE. Special thanks are given to the State Institute for Environment, Measurements and Nature Conservation Baden‐Württemberg (LUBW) and the Provincial Government of Lower Austria for providing data. We thank H. Proske and K. Granica (Joanneum Research, Graz) for providing land cover raster layers for Lower Austria. Finally, we are very grateful to Thiery Oppikofer, an anonymous reviewer and the associate editor A. Kellerer‐Pirklbauer for their constructive comments on an earlier version which helped to significantly improve the manuscript.