REGIONAL-SCALE AQUIFER MAPPING IN CANADA

Groundwater is important to health, economy and ecosystems in Canada. It has been routinely surveyed since early last century, yet groundwater has not been mapped in a systematic way across the country. A current federal groundwater initiative includes establishing a framework to link national, regional and watershed-scale groundwater flow systems. The country can be classified into 9 regions of similar character on the basis of geology, physiographic, and permafrost from existing national maps. These regions provide a first order summary for comparison at 1:1,000,000 scales.

A common approach utilized in developing a national aquifer classification (e.g. United States, Ireland) is the use of geological mapping, and, organization into simple aquifer types. Five types are used in the US national principal aquifer map. A similar approach is applicable to organize regional aquifer mapping in Canada, based on key water-bearing openings: i) porous or inter-granular, ii) fractures, iii) karst. This scheme uses classes such as un-consolidated sand and gravel, sandstone, carbonate, carbonate-clastic and crystalline rocks. A limited set of aquifer types can be linked within hydrogeological settings (e.g. depositional environment/ landform; glaciofluvial/ esker) to permit rapid and simple characterization of hydrogeological conditions (e.g. water table or confined). Aquifer types can be linked to a hierarchical scale of geological maps and hydrogeological regions to facilitate a systematic assessment of groundwater resources in Canada.

Case studies in Ontario are presented defining the 3D distribution, geometry and architecture of individual aquifer settings, e.g. landforms; buried valleys, stratified moraines. Mapping in aquifer settings indicates that they may contain a number of aquifer sub-types, e.g. esker, fan and delta. Improved delineation of these aquifer types requires integration of archival field data organized within a stratigraphic database, and linked to a training framework of high-quality geophysical, sediment core and surface map data. The availability of sound conceptual models and seamless geological mapping will lead to improved 3-D geological modeling that will in turn help constrain the lack of data coverage and data quality encountered in regional hydrogeological mapping.