Preprints
https://doi.org/10.5194/tc-2021-208
https://doi.org/10.5194/tc-2021-208

  26 Aug 2021

26 Aug 2021

Review status: this preprint is currently under review for the journal TC.

Glacier-permafrost relations in a high-mountain environment: 5 decades of kinematic monitoring at the Gruben site, Swiss Alps

Isabelle Gärtner-Roer1, Nina Brunner1, Reynald Delaloye2, Wilfried Haeberli1, Andreas Kääb3, and Patrick Thee4 Isabelle Gärtner-Roer et al.
  • 1Department of Geography, University of Zurich, Zurich, 8057, Switzerland
  • 2Department of Geosciences, University of Fribourg, Fribourg, 1700, Switzerland
  • 3Department of Geosciences, University of Oslo, Oslo, 0371, Norway
  • 4Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zurich, 8903, Switzerland

Abstract. Digitized aerial images were used to monitor the evolution of perennially frozen debris and polythermal glacier ice at the intensely investigated Gruben site in the Swiss Alps over a period of about 50 years. The photogrammetric analysis allowed for a compilation of detailed spatio-temporal information on flow velocities and thickness changes. In addition, high-resolution GNSS (Global Navigation Satellite System) and ground-surface temperature measurements were included in the analysis to provide insight into short-term changes. Over time, extremely contrasting developments and landform responses are documented. Viscous flow within the warming and already near-temperate rockglacier permafrost continued at a constant average but seasonally variable speed of typically decimetres per year, with low average surface lowering of centimeters to decimetres per year. This quite constant flow causes the continued advance of the characteristic convex, lava stream-like rockglacier with its over-steepened fronts. Thawing rates of ice-rich perennially frozen ground to strong climate forcing are obviously very low (centimetres per year) and the dynamic response strongly delayed (time scale decades to centuries). The adjacent cold debris-covered glacier tongue remained an essentially concave landform with diffuse margins, predominantly chaotic surface structure, intermediate thickness losses (decimetre per year) and clear signs of down-wasting and decreasing flow velocity. The former contact zone between the cold glacier margin and the upper part of the rockglacier with remains of buried glacier ice embedded on top of frozen debris exhibits complex phenomena of thermokarst in massive ice and backflow towards the topographic depression produced by the retreating glacier tongue. As is typical for glaciers in the Alps, the clean glacier part shows a rapid response (time scale years) to strong climatic forcing with spectacular retreat (> 10 meters per year) and mass loss (up to > 1 meter water equivalent specific mass loss per year). The system of periglacial lakes shows a correspondingly dynamic evolution and had to be controlled by engineering work for hazard protection.

Isabelle Gärtner-Roer et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-208', Lukas U. Arenson, 12 Oct 2021
  • RC2: 'Comment on tc-2021-208', Anonymous Referee #2, 30 Nov 2021

Isabelle Gärtner-Roer et al.

Isabelle Gärtner-Roer et al.

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Short summary
We intensely investigated the Gruben site in the Swiss Alps, where glaciers and permafrost landforms closely interact, to better understand cold-climate environments. By the interpretation of air photos from five decades, we describe long-term developments of the existing landforms. In combination with high-resolution positioning measurements and ground-surface temperatures, we were able to link these also to short-term changes and describe different landform responses to climate forcing.