Abstract
Abstract. 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 of extracting information from icings that form over the winter and are often still present early in the summer. Primary sources detection was performed using time-lapse camera 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 in the St. Elias Mountains, Yukon. As images alone are not sufficient to entirely cover a large and hydrologically complex area, we explore the possibility of compensating for that limit by using four supplementary methods based on natural tracers: (a) stable water isotopes, (b) water ionic content, (c) dissolved organic carbon, and (d) cryogenic precipitates. The interpretation of the combined results shows a complex hydrological system where multiple sources contribute to icing growth over the studied winter. Glaciers of all sizes, directly or through the aquifer, represent the major parent water source for icing 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 similar results are confirmed in other cold regions, they would together support a multi-causal hypothesis for a general increase in winter discharge in glacierized catchments. More generally, this study shows the potential of using icing formations as a new, barely explored source of information on cold region winter hydrological processes that can contribute to overcoming the paucity of observations in these regions.
Highlights
Winter baseflow increases in response to climatic changes have been observed in a multitude of arctic and subarctic rivers
We propose to compensate for the scarcity of direct observations of winter hydrological processes in glacierized catchments in cold regions by attempting to extract information on potential parent hydrological sources, which we expect is recorded in proglacial icings
In light of the above, the main objective of this study is to explore the possibility of identifying water sources that remain active during the winter in the headwaters of subarctic glacierized watersheds by tracing back those that contribute to the formation of icings
Summary
Winter baseflow increases in response to climatic changes have been observed in a multitude of arctic and subarctic rivers Increases in aquifer storage capacity result from delays in soil freezeup (e.g., Yang et al, 2002), increases in suprapermafrost layer thickness (e.g., Ge et al, 2011; Toohey et al, 2016), or both. These phenomena may lead to an increased amount of water accumulated in the aquifer during summer that can be released during the freezing season. By increasing the aquifer recharge, these sources would indirectly promote an increase in winter discharge
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