CGRG Bibliography of Canadian Geomorphology
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Author : Flowers, G.E.; Clarke, G.K.C.; and Marshall, S.J.
Date : 2003.
Title : Hydrologically coupled simulations of the glacial cycle in North America.
Publication : Canadian Geophysical Union. Annual Meeting, May 10 -14, 2003. Banff Centre, Banff, Alberta.
Issue :
Page(s) :
Abstract
Terrestrial and marine records suggest that basal hydrology may have had an important influence on the history and dynamics of the North American ice sheets, particularly during deglaciation. Water at the bed of a glacier facilitates basal motion through sliding and substrate deformation, which, in turn, affect the geometry of the ice sheet. Areas very sensitive to hydrology include surge lobes and other regions of the ice margin. We have coupled ice-thermomechanical and hydrological models to objectively resolve the feed-backs operating between them. Ice-sheet hydrology is represented as a two-layered model accounting for drainage at the ice{bed interface and in underlying groundwater aquifers. The capacity of these systems is parameterized in terms of their mapped geological and lithological properties. Temporally varying ice thickness, bed elevation and thermal state, basal and surface melt rates, surface accumulation and ice-marginal lake levels are returned by the thermomechanical model and used by the hydrology model to compute the volume and pressure of basal water. Basal motion is then parameterized in terms of the buoyancy fraction. In simulated glacial cycles, we find the total area of the North American ice sheets to be minimally affected by introducing hydrologically driven basal motion. However, the ice volume record is more sensitive, with a 10-20% reduction in simulated ice volume at last glacial maximum. Simulations with and without groundwater drainage exhibit almost identical behaviour when measured in terms of these global ice variables, but show significant differences in local sectors of the ice sheet. The simulated ice-sheet surface is lowered when any kind of basal motion is introduced, but hydrologically coupled simulations produce much smoother surface profiles than do standard parameterizations based solely on driving stress. Because the controls on ice-sheet hydrology are geological, topographical, thermal and source-related in nature, the hydrologically coupled ice model naturally produces flow enhancement that is spatially selective. This has significant implications for ice-sheet configuration during deglaciation.
Bibliography of Canadian Geomorphology