The ability to conceptualize and represent uncertainty in the geometry, dimensionality, and parameterization of key geosphere processes is a necessary element in the development of credible geosphere models. In crystalline rock typical of the Canadian Shield, these three-dimensional geosphere models are principally composed of discrete fracture network models and numerical groundwater models, which when combined, form an integrated platform for the on-going synthesis of geosphere data.

Fracture network modelling involves using three-dimensional, geostatistical tools for creating realistic, structurally possible models of fracture zone networks within a geosphere that are based on field data. The fracture network models, by honouring and incorporating available site data, allow for a greater understanding of the geometry and interconnectivity of the fractures in a quantitative manner. MoFrac, based upon the legacy fracture network modelling software FXSIM3D, is a new fracture network modelling tool capable of generating fracture network geometry composed of both stochastic and deterministic features.

The groundwater modelling methodologies applied within this project were developed and tested within the NWMO Geoscience Technical R&D program, and provide a numerical framework to assemble and integrate geosphere data including topography, surface water features, fracture networks, and hydraulic conductivities. These geosphere data, when synthesized into a three-dimensional geosphere conceptual model, form the basis for the integrated groundwater systems models. These models provide a quantitative assessment of suitability and facilitate a full understanding of the influences of geosphere factors such as topography, surface water features, and fracture zone geometry and interconnectedness. The numerical groundwater modelling software HGS was employed for this study.

A representative sub-regional scale test case based upon Canadian Shield data was used in order to demonstrate the modelling workflow. Performance measures include groundwater heads, velocity magnitudes, Mean Life Expectancies (MLEs), and depth of recharge of a surficial tracer.