Rockfall at Proglacial Rockwalls—A Case Study from the Kaunertal, Austria
Since the Little Ice Age, high alpine regions have faced rapid glacier melting that has contributed to enhanced rockfall activity at recently deglaciated rockwalls. At the Gepatschferner, Kaunertal (Austria), rockfall activity has been quantified for the past several years using rockfall collector nets, ‘natural’ rockfall traps and multi-temporal LiDAR. Toppling and sliding activity of large unstable rock blocks, considered as precursors of rockfalls, were monitored by steel tape measurements and electrical crackmeters. The highest rockfall activity was measured at recently deglaciated rockwalls with low rock mass quality, where rockwall back-weathering rates locally exceeded 10 mm/a. Those rates are among the highest ever published. 108 mid- and high-magnitude rockfalls with volumes between 100 and 30,000 m3 were released between 2006 and 2012. Their scars are clustered in the proglacial high-altitude parts of the Kaunertal. As well, rockwall activity was concentrated in the autumn and winter months.
KeywordsPROSA project Rockfall rates Displacement rates Crackmeter Rock mass strength
The research work was carried out in the PROSA-joint (High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) project funded by the Deutsche Forschungsgemeinschaft (DFG; grant numbers RO 2211/5-1, RO 2211/5-2, RO 2211/5-3).
We thank Philipp Glira (TU Vienna) and Ludwig Hilger (University of Eichstätt-Ingolstadt) for the excellent preparation of the airborne LiDAR data and Harald Meier, Markus Schleier, Renneng Bi, Johannes Wiedenmann and Ingvar Krieger for their help during the construction of the rockfall collector nets. Further, we acknowledge Tobias Heckmann and Samuel McColl for the suggestions to revise the manuscript and the good ideas to improve it. Finally, we acknowledge the TiWAG hydropower company for granting free access to the mountain road and the Tyrolean government for generously providing airborne LiDAR data of the year 2006.
- Abele G (1974) Bergstürze in den Alpen. Wissenschaftliche Alpenvereinshefte, Number 25, MunichGoogle Scholar
- Bieniawski Z (1973) Engineering classification of jointed rock massesGoogle Scholar
- Engl D, Fellin W, Zangerl C (2008) Scherfestigkeiten von Scherzonengesteinen-Ein Beitrag zur geotechnischen Bewertung von tektonischen Störungszonen und Gleitzonen von Massenbewegungen. Bulletin für angewandte Geologie 13:63–81Google Scholar
- Haeberli W (1975) Untersuchungen zur Verbreitung von Permafrost zwischen Flüelapass und Piz Grialetsch (Graubünden). Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie an der ETHGoogle Scholar
- Heckmann T, Hilger L, Vehling L, Becht M (2016) Integrating field measurements, a geomorphological map and stochastic modelling to estimate the spatially distributed rockfall sediment budget of the Upper Kauner Valley, Austrian Central Alps. Geomorphology 260:16–31. https://doi.org/10.1016/j.geomorph.2015.07.003CrossRefGoogle Scholar
- Luckman B, Fiske C (1995) Estimating long-term rockfall accretion rates by lichenometry. In: Slaymaker O (ed) Steepland geomorphology. Wiley, Hoboken, pp 221–254Google Scholar
- Luckman BH (1973) Scree slope characteristics and associated geomorphic processes in Surprise Valley, Jasper National Park. McMaster University, AlbertaGoogle Scholar
- Moser M, Wunderlich T, Meier H (2009) Kinematische Analyse der Bergzerreißung Hornbergl–Reutte (Tirol). Jahrbuch der Geol. Bundesanstalt 149.1. WienGoogle Scholar
- Noetzli J, Hoelzle M, Haeberli W (2003) Mountain permafrost and recent Alpine rock-fall events: a GIS-based approach to determine critical factors. In: Proceedings of the 8th international conference on permafrost, pp 827–832Google Scholar
- Priest SD (2012) Discontinuity analysis for rock engineering. Springer Science & Business Media, BerlinGoogle Scholar
- Sass O (2005) Spatial patterns of rockfall intensity in the Northern AlpsGoogle Scholar
- Selby M (1980) A rock mass strength classification for geomorphic purposes, with tests from Antarctica and New Zealand. Zeit Geomorph, NF 24:31–51Google Scholar
- Vehling L (2016) Gravitative Massenbewegungen an alpinen Felshängen-Quantitative Bedeutung in der Sedimentkaskade proglazialer GeosystemeGoogle Scholar
- Vehling L, Baewert H, Glira P, Moser M, Rohn J, Morche D (2016b) Quantification of sediment transport by rockfall and rockslide processes on a proglacial rock slope. Kauner Valley, AustriaGoogle Scholar
- Wheaton JM, Brasington J, Darby SE, Sear DA (2010) Accounting for uncertainty in DEMs from repeat topographic surveys: improved sediment budgets. Earth Surf Process Land 35:136–156Google Scholar
- GCD 4.0—Geomorphic change detection software. http://gcd.joewheaton.org/downloads/older-versions/gcd-4-0. Accessed 5 Sept 2017