KEY REGIONAL-SCALE AQUIFERS IN CANADA ASSESSED IN PRE-DEVELOPMENT CONDITIONS

Water is considered as a renewable resource. However, this is not always apparent at the regional scale and life-time scale. The full hydrologic cycle includes both surface water and groundwater Thus, the management of water as a resource should be applied conjunctively to both. Canadians are fortunate to possess abundant surface water and even greater quantities of safe freshwater in the ground. There is ample information on the former but scatter information on the latter. In recent years, however, Canada has seen an increase in awareness of the importance of groundwater and in the assessment of groundwater resources through the detailed characterisation of regional-scale aquifers.

To provide information to groundwater managers, we originally considered the traditional concept of “safe yield” to assess the long-term use of the resource; but discarded it because it can not be sustainable; it ignores the surface-water connection. To account for groundwater feeding riparian zones, rivers and lakes, we adopted the watershed approach. We introduced the revised concept of sustainable safe yield, and suggest its use in the inventory of the Canadian groundwater resources.

Why should Canadians assess the sustainable safe yield of the country's groundwater resources? The main reasons for this are: 1) because given its vast amounts of surface water Canada must adopt the conjunctive surface water-groundwater use; 2) because there is a need to carefully manage its groundwater resources with a long-term sustainable development to prevent over-exploitation; and 3) because knowledge for the sustainable, long-term yield of aquifers is needed in order to adapt to climate changes.

An initiative from the federal government of Canada is presently being developed to integrate groundwater data from across the country in order to assess and monitor regional groundwater systems to address issues of sustainable development. This national program includes an inventory of the groundwater resources of Canada through the assessment and quantification of groundwater resources as a first step to evaluate their sustainability. We present three cases of regional-scale assessments including sustainability issues in the Mirabel and Châteauguay aquifers in the Province of Quebec, and the Annapolis Valley in the Province of Nova Scotia.