Groundwater Storage and Flow Pathways in a Rock Glacier Complex in the Canadian Rockies

Abstract:

Hydrological functions of alpine glaciers and their responses to the warming climate have received much attention by hydrologists working in alpine catchments around the world. As alpine glaciers retreat, they commonly leave debris-covered ice or ice-cored moraine behind, which can remain frozen in ground for many decades or centuries. In many alpine catchments, characteristic landforms indicating rock glaciers or their relicts are found in locations where glaciers do not exist under the current climate. These landscape features associated with mountain permafrost are ubiquitous in alpine catchments, but their hydrological functions have not received much attention. Do rock glaciers and other mountain-permafrost features contribute significantly to storage of snowmelt water and its delayed release to sustain baseflow in the critical alpine stream habitats? How are these storage functions responding to the climate warming? In order to answer these questions, we initiated a hydrological study of rock glaciers in an alpine catchment in the Canadian Rockies in 2014. We will present preliminary results of our study using geophysical imaging techniques, hydro-meteorological monitoring, and groundwater tracing using various environmental tracers. Key findings are: 1) substantial amount of permafrost exists in the rock glacier which is inactive (i.e. no active motion) under the present climate, 2) spatial distribution of permafrost is controlled by both meteorological and geological factors, 3) the rock glacier complex contributes 30-50 % of summer stream flow even though they occupy less than 5% of the catchment area, and 4) the low temperature (< 2 C) of groundwater discharging at the toe of rock glacier plays a significant role in regulating the temperature of stream, which hosts a population of trout species that is listed as "threatened" in the list of the status of endangered wildlife in Canada.