Quantifying ground ice content in the Central Andes, and associated runoff from permafrost degradation in response to climate change

The significance of permafrost occurrences in the Central Andes for the hydrological cycle is currently being discussed in a controversial way. Given the lack of comprehensive field measurements and quantitative data on the local variability of internal structure, ice content and their hydrological contribution of different permafrost landforms, this project aims to improve the total ground ice content quantification from geophysical surveys by making use of field-based data from several extensive geophysical campaigns since 2011 in different high-altitude regions of the Central Andes and corresponding borehole and pit information. Furthermore, an upscaling approach from individual profiles to the watershed scale will be developed and permafrost evolution simulations will be conducted to analyse the contribution of melting ground ice from permafrost to the total runoff of a given watershed.

Aims:

This project has the following objectives:

1. Development of an improved geophysics-based quantification approach for ground ice content in permafrost areas
2. Development of suitable upscaling approaches for ground ice content from individual geophysical profile lines to the catchment scale
3. Modelling and analysis of the contribution of melting ground ice from permafrost for the total runoff of a given watershed
4. Validate the approach by extensive data sets from various field sites in the Central Andes of Chile and Argentina

Study area: Various field sites in the Central Andes of Chile and Argentina

• Project Overview

  Permafrost is a widespread phenomenon at higher altitudes in the dry Central Andes and manifests itself through many quite different landforms, including ice-rich rock glaciers, protalus ramparts and talus slopes. These ice-rich landforms may contain a significant amount of water, especially in otherwise dry parts of mountain regions, typically also for other regions of the worlds, such as Central Asia and the Arctic. Under ongoing climate warming, this ground ice will slowly be released in the hydrological cycle, where it will alter the runoff regime. In addition, degrading permafrost is known to impact the slope stability and may lead to ground settling. These, in turn, impact infrastructures and human settlements at lower altitudes. Industrial development (mainly mining in South America) in permafrost terrain may therefore:

  1. be affected by increasing and unexpected slope instabilities and other permafrost degradation processes (e.g., new and potentially unexpected geohazards, or geohazard changes in frequency and magnitude – changes in material availability);
  2. require carefully analysis of the distribution of ground ice content within their area before project development; and
  3. must quantify the ground ice volume within the project area to assess the amount of current and future water resources, which might be impacted by their operations (e.g., environmental risks and permits).
  4. Need to clearly distinguish runoff changes linked to degrading permafrost and the slow release of “old ice” as the active layer increases in depth from potential impacts from mining projects.

  However, detailed (ground-based) estimates of the permafrost distribution and quantification of its ground ice volume are very scarce in the Central Andes, in contrast to the Swiss Alps, where these variables have been measured for over two decades. A methodology for assessing the ground ice content to depths of up to 60 m along geophysical profiles has recently been developed (Hauck et al., 2011, 2017), however, its application to large areas (catchments) has not been conducted to date. Similarly, long-term climate impact studies regarding the permafrost evolution have been performed at individual sites (1-D), but not in the context of runoff changes from degrading permafrost and thawing ground ice. In the current project we propose to address the objectives listed above by conducting several tasks within the following three work packages:

  1. Quantifying ground ice content through geophysical methods and a new combination of petrophysical relationships
  2. Upscaling and regional ground ice model
  3. Thermo-Cryohydrological simulation of future runoff generation from permafrost areas

  The results will be important in the context of improved environmental impact assessments in the Central Andes and elsewhere, but also regarding the estimation of future changes in the runoff regime at high altitude mountain ranges and the quantification of its components under ongoing climate change. The innovative methodological approach can also be transferred to other permafrost related hydro-thermal research questions, such as in the field of geohazards.

• Publications
  • Hauck, C., Böttcher, M., and Maurer, H. 2011. A new model for estimating subsurface ice content based on combined electrical and seismic data sets. The Cryosphere, 5(2): 453-468.
  • Hauck, C., Hilbich, C. and Mollaret, C. 2017. A Time-lapse Geophysical Model for Detecting Changes in Ground Ice Content Based on Electrical and Seismic Mixing Rules. In 23rd European Meeting of Environmental and Engineering Geophysics, doi:10.3997/2214-4609.201702024.
  • Hauck, C. and Hilbich, C. (2018): Quantifying ground ice content and its variability in permafrost bodies using geophysical techniques: implications for water release and future water availability. In EGU General Assembly Conference Abstracts (Vol. 20, p. 10605).
  • Hilbich, C., Delaloye, R., Hauck, C., Mollaret, C. & Niggli, L. (2018): Towards accurate quantification of ice content in permafrost of  the Central Andes – results from geophysical campaigns in 3 different regions. 5^th European Conference on Permafrost, Chamonix/France.