Proglacial icings as records of winter hydrological processes

• Main Authors: Chesnokova, Anna, Baraër, Michel, Bouchard, Émilie
• Format: Text
• Language: English
• Published: 2020
• Subjects: Yukon; Subarctic
• Online Access: https://doi.org/10.5194/tc-2020-63; https://tc.copernicus.org/preprints/tc-2020-63/

The ongoing warming of cold regions is affecting hydrological processes, causing deep changes such as a ubiquitous increase in river winter discharges. The drivers of this increase are not yet fully identified, mainly due to the lack of observations and field measurements in cold and remote environments. In order to provide new insights into the sources generating winter runoff, the present study explores the possibility to extract information from icings that form over the winter and are often still present early in the summer. Primary sources detection is performed using time lapse camera (TLC) images of icings found in both proglacial fields and upper alpine meadows in June 2016 in two subarctic glacierized catchments in the upper part of the Duke watershed, St. Elias Mountains, Yukon. As TLC alone are not sufficient to entirely cover a large and hydrologically complex area, we explore the possibility to compensate that limit by four supplementary methods based on natural tracers: (a) stable water isotopes, (b) water ionic content, (c) dissolved organic carbon (DOC), and (d) cryogenic precipitates. Interpretation of the combined results shows a complex hydrological system where multiple sources contribute to icings growth over the studied winter. Glaciers of all sizes, directly or through the aquifer, represent the major parent water source for icings formation in the studied proglacial areas. Groundwater-fed hillslope tributaries, possibly connected to suprapermafrost layers, make up the other detectable sources in icing remnants. If confirmed in other cold regions, those results will suggest orienting winter flow trend studies toward a multi-causal hypothesis in glacierized catchments. More generally, this study shows the potential of using icing formations as a new, barely explored source of information on cold regions’ winter hydrological processes that can contribute to overcoming the paucity of observations in these regions.