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

在加拿大各地的许多司法管辖区，水资源管理人员正试图在不同的尺度上为流域制定准确的水资源预算。在这些流域被浅层基岩含水层覆盖的地方，使用主要为砂砾含水层开发的水预算方法的可行性被发现是错误的。例如，我们在安大略省环境部、里多山谷保护局、卡塔拉基地区保护局和昆特地区保护局的合作伙伴最近的研究表明，在裂隙基岩中，估计多孔介质中地下水补给量的传统方法可能非常不准确。不准确的补给估计的后果是可怕的，因为我们现在依赖这些估计来确定取水(即装瓶水、工业需求和市政需求)对地下水和地表水供应的影响，并估计气候变化的潜在影响。在第一次此类研究中，我们建议开发更专门设计的新工具，以在当地和分水岭尺度上准确预测裂隙基岩含水层中的地下水补给。研究的重点将是实地研究和模型开发，利用之前在安大略省东部900平方公里的分水岭进行的工作。我们的第一步将是确定在这种情况下一年中实际补充了多少水。通过对补给机制的理解，我们建议发展一种新的数值模拟方法、新的地球化学方法和新的水力测量方法来改进浅层基岩地区的补给估算。我们坚信，这项研究的结果将改变在这些环境下估计补给和防止过度开采的工程和科学实践标准，并将极大地有利于加拿大其他利用基岩含水层的地区，如不列颠哥伦比亚省南部、魁北克、安大略省其他地区和加拿大大西洋地区。一名博士生和四名硕士研究生将在为期三年的学习过程中接受培训。

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.