Numerical modelling of integrated hydrogeological systems in complex porous and fractured media

加拿大拥有世界上最丰富的地下水资源，这些资源对饮用水、农业和工业用途以及维持生态系统和河流流量至关重要。这些资源正受到过度开采、污染和气候变化的威胁。一些最复杂的地下水系统是在裂隙多孔介质中发现的，这对表征、修复和保护都具有挑战性。 这个发现补助金提案“复杂多孔和裂隙介质中综合水文地质系统的数值模拟”概述了一项研究计划，用于开发和应用新的计算建模方法来测试概念模型，以更好地保护和管理地下水资源，并提高我们修复污染场地和防止未来影响的能力。该提案部分是在研究员的加拿大二级断裂多孔介质定量水文地质学研究主席的背景下制定的。 该提案包含三个主要研究主题，涉及裂缝系统的数值模拟： 1.裂隙岩石含水层地下水资源保护数值方法的发展， 2.应用数值模型优化受污染的裂隙含水层的补救， 3.了解在应力条件下断裂水文地质系统的风险。 为确保有限的地下水资源的可持续利用而开发量化的数字工具是涵盖所有主题的基本目标。 该提案的主题1将侧重于开发新的数值工具和建模方法，以保护断裂岩石含水层中的地下水，这些含水层越来越普遍地用于城市和农村供水。新的计算技术，以确定水源的城市供水威尔斯在破碎的岩石，并预测地下水年龄和预期寿命作为衡量含水层和井的脆弱性，分别将充分开发离散断裂多孔介质在三维空间。 对于已经受到污染的含水层，需要采取更有效和更具成本效益的补救方法。在主题2下，将开发一个强大的三维数值流动和传输模型，用于模拟石油烃污染地下水的“处理列车”过硫酸盐-ISCO（原位化学氧化）修复。该方法包括硫酸盐增强原位生物修复（IBR），再加上与自然背景地球化学反应。该模型将为多孔和离散裂缝多孔介质开发，并将在各种水文地质条件下的监测现场进行测试。将研究最佳设计参数（包括注入浓度、流速和处理顺序时间）、不确定性以及非均质性和背景地球化学的影响。 主题3讨论页岩气开发对地下水资源的环境影响，重点是模拟水力压裂对裂隙岩石中深层区域流动系统的潜在干扰，并评估甲烷气体和地层卤水泄漏到浅层淡水含水层的风险。这些环境对当前的模型提出了挑战，需要创新的数字策略来充分理解。模拟结果将用于帮助设计地下水监测战略，以便及早发现对饮用水资源的影响。 该提案将导致直接HQP培训2个硕士和2个博士生。

Canada has some of the world's most abundant groundwater resources which are critical for drinking water, agricultural and industrial use, and for maintaining ecosystems and stream flow. These resources are being threatened by over-exploitation, contamination and climate change. Some of the most complex groundwater systems are found within fractured porous media which are challenging to characterize, remediate, and protect. This Discovery Grant Proposal "Numerical modelling of integrated hydrogeological systems in complex porous and fractured media" outlines a research plan for developing and applying new computational modelling approaches to test conceptual models, to better protect and manage groundwater resources, and to improve our ability to remediate contaminated sites and prevent future impacts. The proposal has been developed in part within the context of the Researcher's Tier II Canada Research Chair in Quantitative Hydrogeology of Fractured Porous Media. The proposal contains three primary research themes involving numerical modelling of fractured systems: 1. Development of numerical methods for protecting groundwater resources in fractured rock aquifers, 2. Applying numerical models to optimize remediation of contaminated fractured aquifers, and 3. Understanding the risks from fractured hydrogeological systems under stressed conditions. Developing quantitative numerical tools for ensuring sustainable use of limited groundwater resources is the underlying objective encompassing all themes. Theme 1 of the proposal will focus on developing new numerical tools and modelling approaches for protecting groundwater in fractured rock aquifers which are becoming more commonly used for urban and rural water supply. New computational techniques for identifying source water provenance for municipal water supply wells in fractured rock, and for predicting groundwater age and life expectancy as a measure of aquifer and well vulnerability, respectively, will be fully developed for discretely-fractured porous media in three dimensions. In aquifers which are already contaminated, more efficient and cost-effective remediation methods are needed. Under Theme 2, a robust 3D numerical flow and transport model will be developed for simulating 'treatment-train' persulfate-ISCO (in-situ chemical oxidation) remediation of groundwater contaminated by petroleum hydrocarbons. The approach includes sulfate-enhanced in-situ bioremediation (IBR), coupled to reactions with the natural background geochemistry. The model will be developed for both porous and discretely-fractured porous media, and will be tested at monitored field sites under various hydrogeologic conditions. Optimal design parameters (including injection concentrations, flow rates, and treatment sequence timing), uncertainty, and effects of heterogeneity and background geochemistry will be investigated. Theme 3 addresses environmental impacts of shale gas development on groundwater resources, focusing on simulating potential disturbances to deep regional flow systems in fractured rock caused by hydraulic fracturing, and assessing the leakage risks of methane gas and formation brines into shallow freshwater aquifers. These environments challenge current models and require innovative numerical strategies to fully understand. The simulation results will be used to help design groundwater monitoring strategies for early detection of impacts on drinking water resources. The proposal will lead to direct HQP training of 2 MSc and 2 PhD students.