Internal structure of a large, complex rock glacier and its significance in hydrological and dynamic behavior: A case study in the semi‐arid Andes of Argentina

Abstract

This paper presents an analysis of the internal structure, hydrogeology and dynamics of a large, complex, multilobate and multiroot rock glacier combining electrical resistivity tomography (ERT), hydrochemical data and differential interferometry synthetic aperture radar (DInSAR). The rock glacier consists of a series of overlapping lobes that represent different advancing stages with different degrees of conservation. The ERT surveys characterize the active layer and the upper part of the permafrost layer, the latter showing a heterogeneous geometry and electrical resistivity values ranging from 7 to 142 kΩm. Hydrochemical data argue for both the existence of different disconnected water flow pathways inside the rock glacier and the remarkable ionic concentrator effect of this landform. The horizontal displacement from October 2014 to April 2017 shows greatest magnitudes in the upper sector of both tongues, reaching speeds of up to 150 cm/year. The active frontal sector shows a displacement rate of 2-4.5 cm/year. This study contributes to knowledge of the material properties of rock glaciers, which are considered to represent important reservoirs/ water resources, and their influence on the distribution of mountain permafrost, hydrology, and dynamics. Finally, to the best of our knowledge, the possible influence of the metal content of the ground on the resistivity values recorded for mountain permafrost is highlighted for the first time.

Mountain Permafrost Hydrology—A Practical Review Following Studies from the Andes

“…Several authors have suggested that rock glaciers, for example in the Dry Andes and the Himalaya, are hydrologically important or significant based on the potential volume of water stored in permafrost ground ice estimated using empirical approaches [24,[76][77][78][79][80][81][82][83][84][85][86][87]. Empirical estimates of ground ice volume are subject to substantial uncertainties; for example, Jones et al [76] wrote in a review of these studies that: "[ .…”

Internal structure and water routing of an ice-debris landform assemblage using multiple geophysical methods in the semiarid Andes

“…Similar flow paths have been suggested for other intact rock glaciers worldwide. Supra-permafrost flow has been observed in other mountain permafrost landforms in the Canadian Rockies (e.g., Langston et al, 2011), the Andes (e.g., Trombotto-Liaudat et al, 2020Villarroel et al, 2022) and the Alps (e.g., Rogger et al, 2017), as permafrost impedes its infiltration, evidencing a clear response in the hydrographs, even being heard when standing on it. Subpermafrost flows have been also deduced to occur in the Argentinean Andes (Trombotto-Liaudat, et al, 2020;Villarroel et al, 2022) and the Alps (Krainer and Mostler, 2002;Ikeda et al, 2008), based on indirect outcomes from hydrochemical and geodetic studies.…”

Identifying mountain permafrost degradation by repeating historical ERT-measurements

“…Significant socioeconomic impacts are projected on human livelihoods as a result of mountainous permafrost degradation (Beniston et al, 2018;Hock et al, 2019). Perennial subsurface ice content acts as a significant fresh-water resource although the time-scales of melting and corresponding runoff contributions are still unclear (Hilbich et al, 2022;Jones et al, 2018;Villarroel et al, 2021). Rock and debris-slope instability results in increased rock-fall and debris-flow frequency and intensity, as well as landslide activity (Chiarle et al, 2021;Deline et al, 2015;Frauenfelder et al, 2018;Haeberli et al, 2017;Patton et al, 2019).…”

“…Kenner et al, 2017;Kneisel et al, 2000;Lambiel and Pieracci, 2008;Scapozza et al, 2011), and rock glaciers (e.g. Buckel et al, 2022;Frauenfelder et al, 2008;Halla et al, 2021;Kellerer-Pirklbauer and Kaufmann, 2018;Maurer and Hauck, 2007;Villarroel et al, 2021). ERT surveys have also been applied to study bedrock permafrost on several mountains in the alps (Keuschnig et al, 2017;Krautblatter et al, 2010;Krautblatter and Hauck, 2007;Magnin et al, 2015Magnin et al, , 2017.…”

“…Since alpine permafrost landforms are often difficult to access due to their remote location in high mountains, several challenges arise: If no infrastructure such as roads, cable cars or airborne transport is available, the heavy weight of the equipment has to be transported by human power (Frauenfelder et al 2008;Buckel et al, 2021;Halla et al, 2021;Villarroel et al, 2021). The standard measuring equipment includes the control unit, cables, steel pikes, sponges, salt, hammers, canisters, and an adequate amount of water depending on subsurface moisture and the number of electrodes needed for the measurement.…”