Abstract
Abstract. Permafrost is being degraded worldwide due to the change in external forcing caused by climate change. This has also been shown to affect the morphodynamics of active rock glaciers. We studied these changes, depending on the analysis, on nine or eight active rock glaciers, respectively, with different characteristics in multiple epochs between 1953 and 2017 in Kaunertal, Austria. A combination of historical aerial photographs and airborne laser scanning data and their derivatives were used to analyse surface movement and surface elevation change. In general, the studied landforms showed a significant acceleration of varying magnitude in the epoch 1997–2006 and a volume loss to variable degrees throughout the investigation period. Rock glaciers related to glacier forefields showed significantly higher rates of subsidence than talus-connected ones. Besides, we detected two rock glaciers with deviating behaviour and one that showed an inactivation of its terminal part. By analysing meteorological data (temperature, precipitation and snow cover onset and duration), we were able to identify possible links to these external forcing parameters. The catchment-wide survey further revealed that, despite the general trend, timing, magnitude and temporal peaks of morphodynamic changes indicate a slightly different sensitivity, response or response time of individual rock glaciers to fluctuations and changes in external forcing parameters.
Highlights
Rock glaciers are a downslope creep phenomenon of mountain permafrost and are responsible for extensive mass transport in alpine environments (Barsch, 1996)
Eight active rock glaciers representing different characteristics and conditions were investigated in detail regarding flow velocities and one more regarding surface elevation change
Since the mean annual surface elevation changes allow for a better comparison of rock glaciers of different sizes, we describe them in more detail in the text
Summary
Rock glaciers are a downslope creep phenomenon of mountain permafrost and are responsible for extensive mass transport in alpine environments (Barsch, 1996). Active rock glaciers consist of a generally coarse debris layer (active layer), covering ice supersaturated debris and forming lobate or tongue-shaped landforms (Haeberli et al, 2006). They can be found in most cold mountain regions of the earth (Jones et al, 2019). Borehole cores and inclinometer measurements from different rock glaciers reveal the internal structure and deformation of these landforms (Arenson et al, 2002; Krainer et al, 2015; Buchli et al, 2018). The ice-rich permafrost body constitutes the main layer of the rock glacier, with a smaller proportion of coarser debris per volume than the active layer and volumetric ice contents between 40 %– 90 %
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