Glacial hydrological system characterization using ground-penetrating radar

Abstract

Hydrological systems near the terminus of a high Arctic glacier and a proglacial icing on Bylot Island, Canada, were investigated using ground-penetrating radar (GPR). The ice thickness and the location and depth of tunnels within the glacier and icing were imaged. Modelling of the GPR response was utilized to predict the data quality and to assist in its interpretation. The unique properties of the ice enabled velocity determinations from the diffraction patterns generated by point-source reflectors as well as traditional velocity surveys. The propagation velocity of the radar pulses through the ice depended on the air and water content in the ice. The identification of drainage tunnels was attained through pulse polarity analysis and interpolation between the profiles in gridded surveys. It was found that reflectivity analysis may enable GPR to be used for acquiring three-dimensional information on the thermal structure of glaciers. The much more complicated structure of the icing was imaged with higher frequency antennae and it was found that general ice types could be mapped using radar stratigraphical analysis. Both buried slush mounds and subsurface channel fills were identified within the icing. A portion of the icing near the centre of the valley floor, that has persisted perennially for over 50 years, was found to be sitting on a slightly higher area of the valley bottom and thus was not subjected to the same hydrothermal erosional forces as the edges of the icing, setting up a feed-back loop encouraging the preservation of the central core of ice and promoting the destruction and rebuilding of the edges every year. Copyright © 2000 John Wiley & Sons, Ltd.