Are rock glaciers preferential meltwater pathways to alpine aquifers?

A limitation in generating reliable projections of the impact of climate change on subarctic glacierized watersheds is a lack of understanding of the involved processes. While glaciers are often the targets of glacierized watershed research, glaciers are only one of the many features controlling headwater hydrology. Recent studies suggest that the contribution and evolution of other hydrological components under climate change conditions, as well as their interactions with groundwater and surface runoff, must be considered to fully predict future climate change impacts. For example, rock glaciers are recognized for their hydrogeological significance, but their hydrologic processes remain understudied. We present a research program focused on a 5 km² glacier and rock glacier continuum in the upper section of Shar Ta Gà’ (Grizzly Creek) in the Kluane First Nation territory, Yukon, Canada. The continuum is characterized by the absence of an apparent surface hydrology outlet and no substantial groundwater exfiltration has been detected in the Shar Ta Gà’ River situated directly downstream of the rock glacier. Some diffuse groundwater seepages have been mapped but their yield represent a fraction only of the volumes that are expected from the glacier drainage area.

We apply a multimethod approach (including geophysics, hydrochemistry, and UAV based surveying) to characterize the hydrological and hydrogeological behavior of the Shar Ta Gà’ rock glacier in a context where drilling is prohibited. Here we present results from a distributed hydrologic monitoring network of extreme precipitation events that occurred between 2018 and 2022. The network records water pressure, electrical conductivity, water temperature, hydrometeorological data and time lapse images. The results depict the rock glacier as a complex, multi-channel, evolutive hydrogeological system that collects water from upstream channels and from a porous surface. The water is distributed among different reservoirs and/or preferential channels. The rock glacier appears being a node in the hydrological and hydrogeological system, collecting the waters from the continuum and allowing their transfer to granular aquifers and possibly fractured aquifers.