Towards a sediment transfer capacity index of rock glaciers: Examples from two catchments in South Tyrol, (Eastern Italian Alps)

Rock glaciers are active sediment transport systems of high mountain periglacial environments. Driven by the internal deformation of their frozen core, they can convey substantial amounts of debris from their nourishing zone towards their front. Depending on the topographic conditions at the front slope, the released sediment is either overridden again by the advancing rock glacier or transferred downwards by rapid mass movements. The capacity of rock glacier environments to transfer sediment however has remained largely unexplored, in particular beyond the local scale. In this work, we consider a rock glaciers' sediment transfer capacity as a function of its transported volume rate and the travel range of mobilized material at its front. A GIS-based method, low in data-demand, is proposed to generate catchment-scale proxies for the above-mentioned input variables and to combine them to a qualitative index describing sediment transfer capacity of rock glacier fronts. The proposed method is applied in two basins, strongly characterized by periglacial dynamics (Ultental and Schnalstal in South Tyrol, Eastern Italian Alps). In a final step, computed sediment transfer classes are assessed on their geomorphological plausibility by building empirical relationships with independent environmental variables.

Automated summary

This study investigates the sediment transfer capacity of rock glaciers and proposes a GIS-based method to assess their sediment transfer capacity. By considering factors such as topographic conditions and sediment transport rate, this method provides a qualitative index to evaluate the sediment transfer capacity of rock glacier fronts. The feasibility of this method is evaluated through field observations, data analysis, and empirical relationships.