IAHS2022-267, updated on 23 Sep 2022
IAHS-AISH Scientific Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Potential hydrological pathways using geoelectric and georadar in a covered glacier complex in the Chilean semiarid Andes

Gonzalo Navarro1,2, Shelley MacDonell2, and Rémi Valois3
Gonzalo Navarro et al.
  • 1Doctorado en Energía Agua y Medio Ambiente, Universidad de La Serena, Avenida Raúl Bitrán 1305, La Serena, Chile
  • 2Centro de Estudios Avanzados en Zonas Áridas – CEAZA, Raúl Bitrán 1305, La Serena, Chile
  • 3Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes, Université de Avignon - EMMAH, Domaine Saint-Paul, Site Agroparc 228, Avignon, France

Rock glaciers play an important hydrological role in the semiarid Andes (SA; 27°-35°S). They cover about three times the area of uncovered glaciers and represent important contribution to streamflow when water is needed most. For this reason, their role in freshwater production, transfer and storage is likely to be of primary importance. Their internal composition (i.e. ice, water, debris and air) and distribution (e.g. ice lenses, massive ice, hydrological channels) determine how water is transfer through the geoform. To understand such processes, geophysical surveys were conducted in the Tapado glacier complex in the Chilean SA (30°S; above 4200 masl), which could be regarded as the biggest and most relevant ‘water tower’ of the Elqui River catchment. Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) were used and qualitatively combined to delineate potential hydrological routing pathways on the debris-covered and rock glacier, which are part of the complex glacier. The media is characterized by high resistivities and a general pattern of increasing resistivities with depth, associated with the presence of buried ice. Radargrams shows diffraction linked to boulders presence, but strong and diffuse reflectors indicative of ice lenses or massive ice were also recognized. The results suggest that while the covered glacier shows probable hydrological routing zones exclusively in the area above the massive ice, the rock glacier would have more hydrological transfer routes downstream due to its fragmented ice structure, with vertical passages that could conduct water channeled from the thawing ice or from water coming from upstream. This work reinforces the valuable use of geophysical methods in exploring the internal structure of geoforms with ice contained below rock blocks. In addition, it allows to improve the understanding of headwaters in snow and ice melt driven hydrological system, where rock glaciers represent an important unknown when developing models of energy and mass flow (e.g. water), and how these flows interact with adjacent geoforms (e.g. moraines, valleys, peatland).