A numerical study of regional hydrostatic and sub-hydrostatic groundwater regimes in the Western Canada Sedimentary Basin

Amandeep Singh, Joseph Riddell, G.F. Huff, Dan Palombi

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Regional Aquifer Characterization I

ABSTRACT: A regional-scale study of groundwater flow dynamics is being undertaken in the Western Canada Sedimentary Basin, comprising parts of Alberta, Saskatchewan and British Columbia. The objective of the study is to develop a numerical model of basin-scale hydrogeology. The basin-scale model will subsequently provide boundary conditions for local-scale groundwater management models. The basin-scale model includes post-Colorado group aquifers, composed of late Cretaceous to Recent sediments, attaining maximum thicknesses of >2600 m. The study area is bound to the west by the Brazeau-Waptiti thrust (deformation) belt and to the south by the Canada-USA international border. The outcrop/subcrop of the upper-Cretaceous aged Colorado Group (top of the Lea Park Formation) along with Pierre Shale group forms lateral boundaries in the north and east as well as the basal boundary of our model. Major surface water bodies within the modeled area are the Peace, Athabasca, North and South Saskatchewan rivers. Topography varies from >1700 m in the west toward the Rocky Mountains to <600 m in the plains of Saskatchewan in the east. Aquifer units identified for the study include the major lithostratigraphic units and their equivalents from land surface to the top of the Lea Park Formation consisting of the Quaternary sediments, and the Paskapoo, Scollard, Horseshoe Canyon formations and the Belly River Group. The regional aquitards in the study area have been delineated as the Battle and Bear Paw formations. Previous work in the Alberta Basin has acknowledged the fact that in addition to topography controlled conditions, a substantial part of the basin demonstrates sub-hydrostatic regimes. The block-centric, finite difference groundwater code MODFLOW is being used to construct the basin-scale model. Preliminary results from the groundwater flow modeling indicate predominance of topography-driven, local- to intermediate-scale flow systems in the upper hydrostratigraphic units (Quaternary, Paskapoo, Scollard) with recharge of these units occurring in the foothills of the Rocky Mountains. The Battle aquitard, where present, acts as a regional flow barrier in the model. Flow paths in the Horseshoe Canyon Formation and Belly River Group hydrostratigraphic units are influenced by regional scale topography-driven flow systems and sub-hydrostatic pressure regimes.

Please include this code when submitting a data update: GEO2013_317

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