Sediment transfer and connectivity at the front of rapidly moving rock glaciers

Rock glaciers represent important sediment transfer agents in periglacial alpine hillslopes. Large volumes of rock debris originating from headwalls and moraines are slowly transported downward by permafrost creep. In the Alps, most rock glaciers can be considered as sediment traps, because the sediment output at their margin is usually small. However, exceptions exist where a significant erosion rate can be observed at the front. In these cases, rock glaciers can act as the sediment source favoring the triggering of gravitational processes such as debris flows and rock falls. In such case, it is important to better understand the sedimentary link that can exist between the front of rock glaciers and torrential network systems.

A first aim of this research project is to investigate the mechanisms responsible for the erosion of the front of active rock glaciers. In particular, the occurrence of erosion processes and their intensity (quantification) is assessed at different time scale by the application of a multi-method approach including webcam observations, Terrestrial laser scanning measurements, GNSS surveys and photogrammetric analysis. A second goal of this project is to inventory rock glaciers with topographical configurations favouring the supply of torrents with sediment.

 

Collaborators: Mario Kummert (PhD student), Reynald Delaloye (Professor)

Contact: mario.kummert[at]unifr.ch

Duration: 2013-2018

Study area: Valais (western Swiss Alps)

 

  • Illustrations

    Animation of the evolution of the surface elevation at the front of the Dirru rock glacier and in the gully downward in comparison to the initial state (26.06.2014). Surface lowering (red) represents erosion and surface uplift (blue) represent accumulation.

  • Publications
    • Kummert, M. & Delaloye, R. (2018). Regional-scale inventory of periglacial moving landforms connected to the torrential network system. Geographica Helvetica, 73, 357-371. DOI: 10.5194/gh-73-357-2018

    • Kummert, M. & Delaloye, R. (2018). Mapping and quantifying sediment transfer between the front of rapidly moving rock glaciers and torrential gullies. Geomorphology 309C, 60-76.
    • Kummert, M., Delaloye, R. & Braillard, L. (2017). Erosion and sediment transfer processes at the front of rapidly moving rock glaciers: systematic observations with automatic cameras in the western Swiss Alps. Permafrost and Periglacial Processes 29, 21-33. DOI: 10.1002/ppp.1960link
    • Kummert, M. & Delaloye, R. (2015). Quantifying sediment transfer between the front of an active alpine rock glacier and a torrential gully. In: Geomorphometry for Geosciences (2015), Jasiewicz J., Zwolinski Zb., Mitasova H., Hengl T. (eds)Adam Mickiewicz University in Poznan - Institute of Geoecology and Geoinformation, International Society for Geomorphometry, Poznan, 193 - 196 Pdf