CGRG Bibliography of Canadian Geomorphology
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Author : Burgess, D.
Date : 2006.
Title : Ice dynamics and recent geometric changes of the Devon Island ice cap,Nunavut, Canada.
Publication : Unpublished PhD dissertation. University of Alberta, Edmonton,
Issue :
Page(s) :
Abstract
In this study, recent changes in geometry and dynamics of the Devon Island ice cap are quantified from remote sensing techniques and field observations. Comparisons of the ice margin position in 1960's aerial photography and 1999 Landsat7 ETM+ imagery indicate a net decrease in area by -338 ± 40 km2 or 2.4%, over this time period. The dominant changes include retreat of tidewater glacier margins on the eastern side of the ice cap, shrinkage of the southwest arm, and increased bedrock exposure in the ice cap interior. Variability in the changes observed reflect inter-basin differences in the sensitivity of glacier mass balance to climate warming. Surface velocity fields mapped across ~95% of the ice cap using satellite radar interferometry indicate that the western half of the ice cap is dominated by relatively uniform 'sheet' flow, but 3 fast-flowing outlet glaciers that extend 14--23 km beyond the ice cap margin also drain this region. Several outlet glaciers that extend up to 60 km inland from the easternmargin drain the eastern side of the ice cap. Four dominant ice flow regimes were derived from the relationship between the driving stress and the ratio of surface velocity to ice thickness and indicate that ~22% (8%) of the east (west) half of the ice cap is sliding at the glacier bed. The volume of ice calved between 1960 and 1999 was estimated to be 20.5 ± 4.7 km3 of ice which accounted for ~30% of the total blation for this interval. Long-term thickness change rates were derived at several spatial scales across most of the Devon Island ice cap. Results reveal accumulation zone thinning throughout the southern and eastern basins with a maximum rate of ~ -0.23 ma-1 in the southeast sector. Dynamic thinning by of the Southeast 1 and possibly Southeast 2 outlet glaciers above the ELA likely contributes to the basin-wide thinning of the southeast accumulation zone. Dynamic thinning of ~ -2 m occurs near the terminus of the Belcher Glacier as well as thinning by ~ -2 m along the lower reaches of the South Croker Bay Glacier. Dynamic thickening by up to ~2 m along the lower reaches of the North Croker Bay Glacier and by ~1 m in the ablation zone of the southeast region along the Southeast 1 and 2 Glaciers prevails. In total, the main portion of the Devon Island ice cap has decreased by -74 ± 9 km3 of ice (67 ± 7 km3 water equivalent) between 1960 and 1999, contributing ~0.19 mm to global sea-level rise over this time period
Bibliography of Canadian Geomorphology