Changing debris cover on Eastern Alpine glaciers: Quantification and hydrological impacts

Climate observations as well as climate scenarios reveal a rise of temperatures around the globe, with almost twice the global rate in Austria. This temperature increase affects glacier and permafrost distribution in the Alps. Glacier retreat is the most visible manifestation of climate change in high mountain areas and has a significant impact on high mountain runoff. With glacier downwasting and increasing rock fall activity, debris depositions accumulate at current glacier tongues, which partly reduces ice ablation and favours ice storage beneath debris.

In addition, this debris, once deposited in the proglacial area, can be assumed to be closely connected to transport in the stream system. In general, areas in the transition from glacial to non-glacial conditions are highly unstable and prone to erosion over a wide range of discharge, but particularly to export of sediments in case of heavy precipitation events.

The project serves to investigate the hydrological impact of supraglacial debris deposits in the transition zone from glacier ice to proglacial areas in Austria.

First, the project will apply a nation-wide mapping of supraglacial debris and investigate hotspots of increasing debris cover. A detailed study of processes of debris deposition and renewed movement by fluvial transport will be performed at the LTER site Jamtalferner, combining hydrological modelling of the potential transport capacity of sediments in glacial streams, the analysis of grain size distribution on the glacier surface and in the proglacial area, and the calculation of sediment volume changes from UAV-based photogrammetry. Further, documentation of the historical evolution of the channel network will increase our knowledge of the temporal evolution of sediment-rich, proglacial zones.

The project makes use of ongoing improvements in the temporal and spatial resolution of remotely sensed data from different platforms (satellite, airborne, UAV-based). In particular, this study will expand the monitoring capabilities at the well-established LTER site Jamtalferner to build up long-term datasets.