EVALUATING A NESTED-SCALE 3D MODELLING APPROACH TO ENHANCE GROUNDWATER POLICY ASSURANCE IN ALBERTA

Provincial regulators of the Water Act in Alberta, Canada are working to develop an enhanced groundwater management framework that utilizes geological modelling, groundwater mapping, and hydrogeological modelling. A growing demand for water reinforces the need to understand and quantify the cumulative effects of groundwater development across water-use sectors. The Alberta Energy Regulator – Alberta Geological Survey (AGS) and Alberta Environment and Sustainable Resource Development (AESRD) are evaluating long-term sustainable methods to water resource management. Through pilot projects and workshops, geoscientists and model users within AGS and AESRD have determined that a nested-scale geological and hydrogeological model development approach is required to evaluate cumulative impacts of groundwater authorizations and thresholds for sustainable use.

In this work we demonstrate two nested-scale studies: 1) development of a basin-scale (approx. 420,000 km²) groundwater flow model of the Upper Cretaceous aquifers across the Western Canada Sedimentary Basin; and 2) a regional-scale (approx. 6000 km²) groundwater study in central Alberta nested within the basin-scale groundwater flow model. Results from the basin-scale modelling indicates the predominance of topography-driven, local- to intermediate-scale groundwater flow systems in the upper hydrostratigraphic units, with recharge occurring in the foothills of the Rocky Mountains. Flow paths in some of the Upper Cretaceous aquifers are influenced by a combination of topography-driven groundwater flow and sub-hydrostatic pressure regimes. A multi-layer hydrostratigraphic model was constructed for the regional-scale study to represent the spatial distribution of depositional elements affecting groundwater flow. 3D hydrostratigraphic reconstructions of the bedrock topography, key bedrock units, and overlying unconsolidated sediments were created through the integration and analysis of multiple subsurface data types. This multi-scale nested approach is intended to provide boundary conditions for groundwater management models hosted within a decision-support system, allowing access to policy-makers and regulators for groundwater management and policy assurance.