Geophysical and Hydrological Investigation of Rock Glacier in the Canadian Rockies

English Abstract:

Anticipated climate warming will lead to increases in the global temperature and evapotranspiration. These changes will affect the peak of the mountain river runoff by shifting it to earlier in the year, away from the peak demand of summer and autumn. The effects of global warming may be buffered by groundwater that is stored temporarily in overburden material such as talus, moraine and rock glaciers, before discharging into mountain streams. Therefore, it is important to understand the contributions of these landscape units to the hydrological cycle in alpine watersheds in order to predict consequences of the climate warming for these natural water reservoirs.

In this project, a rock glacier in the Helen Lake Creek watershed in Banff National Park, Alberta was explored using electrical resistivity tomography, seismic refraction and ground penetrating radar. The main objectives were to identify the presence of ice in the subsurface, determine the depth to bedrock and trace the pathways of groundwater water flow.

Resistivity images showed areas with large resistivity values indicating possible ice locations. Seismic refraction data was consistent with a two-layer system with the velocity range of the lower layer typical for the bedrock. Ground penetrating radar data were consistent with the seismic refraction and resistivity interpretations by showing reflections at the bedrock boundaries.

The geophysical data indicate the location of the bedrock surface, groundwater flow paths and ice in the rock glacier. Their role in the storage and release of water to sustain the late-summer base flow in Helen Lake will be discussed.