CGRG Bibliography of Canadian Geomorphology
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Author : Copland, L.; Sharp, M.; and Nienow, P. W.
Date : 2001.
Title : Relationships between short-term velocity variations and the subglacial hydrology of a high Arctic polythermal glacier.
Publication : Annual Scientific Meeting of the Canadian Geophysical Union. May 14-17, 2001, University of Ottawa, Ottawa.
Issue :
Page(s) :
Abstract
To investigate the relationships between ice flow dynamics and the characteristics and seasonal evolution of the subglacial drainage system of a polythermal glacier, surface velocities were determined for successive two day periods in summer 1998 and 1999 at John Evans Glacier, Ellesmere Island. Two distinct high ice motion events were recorded in 1999, and one in 1998. These events occurred during periods of rapidly increasing meltwater input to the glacier bed: (i) at the start of the summer melt season, and (ii) as air temperatures rapidly rose after a mid-summer cold spell (in 1999). The magnitude of velocity increases during these events was non-uniform, with highest increases above regions of the glacier bed where subglacial drainage is predicted. Early season events were focused close to the glacier snout, where an artesian fountain that occurred in 1998 indicates that basal water pressures reached at least 120% of ice overburden pressure. The mid-season event was focused at the top of the terminus region above an area where vertical velocities suggest closure of drainage passages during the preceding cold spell. These observations suggest that the high motion events were due to enhanced basal motion driven by high basal water pressures that are localised along subglacial drainage pathways.
Bibliography of Canadian Geomorphology