HR: 15:15h
AN: CG13B-06    [Abstracts]
TI: Controls on Groundwater Flow in an Alpine Talus-Moraine Complex
AU: * Muir, D L
EM: dlmuir@ucalgary.ca
AF: Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
AU: Hayashi, M
EM: hayashi@ucalgary.ca
AF: Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
AU: Bentley, L R
EM: lbentley@ucalgary.ca
AF: Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
AB: Since alpine watersheds are the headwaters of rivers acting as major sources of water, there is growing concern over water shortages in areas dependent on mountain runoff. Talus and moraine complexes, as well as fractured bedrock, are a dominant hydrologic response unit within the Lake O'Hara Research Basin (LORB) in Yoho National Park, British Columbia. In this alpine environment, previous studies have shown that groundwater plays an important hydrological role. Although little is known about groundwater storage in these media, they are likely a significant groundwater reservoir and an important control on groundwater flow. The goals of this study are to develop a conceptual model of the talus and moraine complex and the fractured bedrock. The approximately 0.3km2 Babylon drainage basin within the LORB was chosen as the study site as it contains a talus and moraine complex that drains into one gaugeable stream. The conceptual model of this basin has been developed using geophysical, hydrological and hydrogeological methods. Three Ground Penetrating Radar (GPR) and Electrical Resistivity Imaging (ERI) surveys were used to characterize the subsurface structure and water distribution within the talus and moraine complex. The bedrock surface is clearly defined in the GPR profiles and its elevation agrees with that in the ERI inversions. Highly resistive talus material is observable in the ERI results, and areas of low resistivity are found within the bedrock. Hydraulic conductivity estimates of the geologic media, calculated using tracer slug injection and baseflow recession analysis methods, fall within the ranges from gravel to fractured rock. Isotopic hydrograph separations indicate that groundwater is a significant contributor to stream discharge. Linear reservoir models show basin response times of up to 16 hours. The geophysical and hydrological evidence points toward two flow systems operating in the Babylon basin, those of flow through the fractured bedrock and flow through the talus and moraine complex. Understanding the hydrologic characteristics of alpine talus and moraine complexes and fractured bedrock is of great importance to increasing our knowledge of alpine hydrology. The results from this study will enable the estimation of hydrologic parameters of these geologic media and provide valuable information for the predictive modelling of mountain streams.
DE: 1829 Groundwater hydrology
DE: 1835 Hydrogeophysics
SC: Canadian Geophysical Union [CG]
MN: 2009 Joint Assembly