Regional-scale groundwater recharge in fractured bedrock aquifers: Development of defensible water management tools

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In many jurisdictions across Canada, Water Resources Managers are attempting to develop accurate water budgets for watersheds at a variety of scales. Where these watersheds are underlain by shallow bedrock aquifers, the feasibility of using water budgeting methods primarily developed for sand and gravel aquifers has been found in error. Recent studies by our partners in the Ontario Ministry of the Environment, the Rideau Valley Conservation Authority, the Cataraqui Region Conservation Authority and the Quinte Region Conservation Authority for example have shown that the traditional methods for estimating groundwater recharge in porous media are potentially highly inaccurate in fractured bedrock. The consequence of inaccurate recharge estimates is dire, as we now depend on these to determine the impact of water abstraction (i.e for water bottling, industrial requirements, and municipal needs) on groundwater and surface water supplies, and to estimate the potential impacts of climate change. In the first study of its kind, we propose to develop new tools more specifically designed to accurately predict groundwater recharge in fractured bedrock aquifers at the local and watershed scales. The focus of the research will be on both field study and model development, taking advantage of previous work conducted in a 900 km2 watershed located in eastern Ontario. Our first step will be to determine how much water is actually recharged during the year in this setting. By understanding the recharge mechanisms we propose to develop a new numerical modeling approach, new geochemical methods and new hydraulic measurements for the improvement of recharge estimates in areas of shallow bedrock. We strongly believe that the results of this study will change the standard of engineering and scientific practice for estimating recharge and preventing overexploitation in these settings and will greatly benefit other regions in Canada where bedrock aquifers are utilized such as in southern British Columbia, Quebec, elsewhere in Ontario, and in Atlantic Canada. One PhD student and four MSc students will be trained over the course of the three-year study.