HR: 0800h
AN: H11C-1271    [Abstracts]
TI: Impact of the Wisconsinian Glaciation on Canadian Continental Groundwater Flow
AU: * Lemieux, J
EM: jmlemieux@uwaterloo.ca
AF: University of Waterloo, Department of Earth Sciences, 200 University Avenue West, Waterloo, On N2L 3G1 Canada
AU: Sudicky, E A
EM: sudicky@sciborg.uwaterloo.ca
AF: University of Waterloo, Department of Earth Sciences, 200 University Avenue West, Waterloo, On N2L 3G1 Canada
AU: Peltier, W R
EM: peltier@atmosp.physics.utoronto.ca
AF: University of Toronto, Department of Physics, 60 St. George Street, Toronto, On M5S 1A7 Canada
AU: Tarasov, L
EM: lev@atmosp.physics.utoronto.ca
AF: University of Toronto, Department of Physics, 60 St. George Street, Toronto, On M5S 1A7 Canada
AB: During the last glacial period (75 kyr - 10 kyr), the Canadian landscape was almost entirely covered with ice. The Laurentide ice-sheet, the largest of the three North-American ice sheets, reached a thickness of about 4 km and the force exerted by its weight on the earth's crust was sufficient to cause a depression of the surface of about 1 km and an over-pressurization of porewater fluids. These dramatic conditions are suspected to have had a large impact on the groundwater flow system over the whole continent. Although an analysis of the evolution of groundwater flow systems during glacial periods is relevant to a number of problems, such as the long-term stability of high-level spent nuclear-fuel repositories located at depth, very few studies have been conducted to assess the impact of glaciation on deep-seated groundwater flow systems, particularly in a North-American context. A transient, three-dimensional groundwater flow model including the effect of the advective-dispersive redistribution of shield brines was constructed in order to capture the impact of the advance and retreat of the ice sheet over the Canadian landscape. The model is driven by a thermomechanical ice-sheet model of the last glacial cycle [Tarasov and Peltier, 2004] which provides the transient boundary conditions that includes the spatio-temporal distribution of the glacial ice, the elevation of the surface topography, meltwater rates, permafrost thicknesses, as well as temporal changes in sea level along the coastal margins. The evolving surface water drainage patterns and features such as proglacial lakes are also incorporated based on the hydrologic routing calculations performed by Tarasov and Peltier [2005]. The treatment of physical processes related to the influence of the ice sheet on the groundwater flow system such as hydromechanics, isostasy, subglacial melting and permafrost formation are also discussed. Simulation results show that hydraulic heads at depth below the ice sheet increase by several hundred meters and groundwater flow directions also change dramatically from what is observed today. Infiltration of subglacial meltwater also plays a key role in the increase of subsurface hydraulic heads as the meltwater is driven into the subsurface by the weight of the ice.
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
DE: 1807 Climate impacts
DE: 1823 Frozen ground
DE: 1833 Hydroclimatology
DE: 1847 Modeling
SC: Hydrology [H]
MN: Fall Meeting 2005