Preprints
https://doi.org/10.5194/tc-2021-206
https://doi.org/10.5194/tc-2021-206

  23 Aug 2021

23 Aug 2021

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

Towards accurate quantification of ice content in permafrost of the Central Andes, part I: geophysics-based estimates from three different regions

Christin Hilbich1, Christian Hauck1, Coline Mollaret1, Pablo Wainstein2, and Lukas U. Arenson3 Christin Hilbich et al.
  • 1Department of Geosciences, University of Fribourg, Fribourg, 1700, Switzerland
  • 2BGC Engineering Inc., Calgary, AB, Canada
  • 3BGC Engineering Inc., Vancouver, BC, Canada

Abstract. In view of the increasing water scarcity in the Central Andes in response to ongoing climate change, the significance of permafrost occurrences for the hydrological cycle is currently being discussed in a controversial way. The lack of comprehensive field measurements and quantitative data on the local variability of internal structure and ground ice content further enhances the situation. We present field-based data from six extensive geophysical campaigns completed since 2016 in three different high-altitude regions of the Central Andes of Chile and Argentina (28 to 32° S). Our data cover various permafrost landforms ranging from ice-poor bedrock to ice-rich rock glaciers and are complemented by ground truthing information from boreholes and numerous test pits near the geophysical profiles. In addition to determining the thickness of the potential ice-rich layers from the individual profiles, we also use the quantitative 4-phase model to estimate the volumetric ground ice content in representative zones of the geophysical profiles.

The analysis of 52 geoelectrical and 24 refraction seismic profiles within this study confirmed that ice-rich permafrost is not restricted to rock glaciers, but is also observed in non-rock-glacier permafrost slopes in the form of interstitial ice as well as layers with excess ice, resulting in substantial ice contents. Consequently, non-rock glacier permafrost landforms, whose role for local hydrology has so far not been considered in remote-sensing based approaches, may be similarly relevant in terms of ground ice content on a catchment scale and should not be ignored when quantifying the potential hydrological significance of permafrost.

We state that geophysics-based estimates on ground ice content allow for more accurate assessments than purely remote-sensing-based approaches. The geophysical data can then be further used in upscaling studies to the catchment scale in order to reliably estimate the hydrological significance of permafrost within a catchment.

Christin Hilbich et al.

Status: open (until 18 Oct 2021)

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  • RC1: 'Comment on tc-2021-206', Jigjidsurengiin Batbaatar, 14 Sep 2021 reply

Christin Hilbich et al.

Christin Hilbich et al.

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Short summary
In view of water scarcity in the Andes the significance of permafrost as future water resource is often debated focusing on satellite-detectable features such as rock glaciers. We present data from > 50 geophysical surveys in Chile and Argentina to quantify the ground ice volume stored in various permafrost landforms, showing that not only rock glacier, but also non-rock-glacier permafrost contains significant ground ice volumes, and is relevant when assessing the hydrological role of permafrost.