Impact of glaciation on groundwater vulnerability

保护水源是当务之急，因为人口增长、气候变化和污染物给地下水生产井带来了压力。大约1150万加拿大人和全世界20亿人依赖地下水饮用和日常使用，农业(60%的地下水被提取)和工业(20%)还大量使用地下水。这些脆弱的资源在加拿大和世界各地以前冰川地区的冰川沉积物或基岩中发现。管理和保护水井需要一个坚固的地质模型，以确定井场或污染物羽流尺度上与水力有关的地物的几何形状。在以前的冰川环境中，创建这种类型的模型是具有挑战性的，因为在那里，纹理不是控制地下水流动或污染路径的主要驱动因素。最后一次冰期不仅对结构产生了深远的影响，而且还对地下物质的变化分布、地表地形和下垫面基岩表面产生了深刻的影响。此外，基岩的渗透性还受到与地壳回弹和冰期及冰期后水力作用有关的裂解和溶蚀作用或岩溶发育的影响。这一地质历史在确定现代污染物路径和羽流演化、含水层的体积和深度、含水层的完整性、从而决定流动系统特征、油井产能和对污染的敏感性方面发挥着关键作用。虽然地质调查和环境部门在建立区域尺度模型方面取得了很大进展，但井场尺度的冰川沉积的非均质性仍然是一项挑战。*拟议的研究通过以下方式解决这一问题：1)确定特定冰川环境中的典型沉积风格或建筑，并评估其对水质的影响；2)研究冰川过程与下伏基岩之间的相互作用，以及这如何影响基岩含水层中的岩溶分布。将审查大量高分辨率岩心和水质数据，以测试某些地貌和地下沉积物剖面是否比其他地貌更容易受到污染，从而改善井口保护区的划定。冰川过程和基岩之间的关系将通过研究a)埋藏的基岩山谷的地质演化及其与富含岩溶的基岩含水层的出现的关系以及b)沉积物-基岩界面的地质特性来阐明冰下过程并评估是否存在任何有助于地下建模和保护接触含水层的预测关系来探索。*研究成果和5名拥有将冰川地质学应用于水文地质学的急需技能的毕业生将通过促进我们对这些以前冰川地貌的地质历史的理解，对加拿大在井田规模保护地下水的能力产生重大影响。

Source water protection is a priority as population growth, climate change and contaminants have put pressures on groundwater producing wells. Approximately 11.5 million Canadians and 2 billion people worldwide rely on groundwater for drinking and daily use, with additional significant use by agriculture (60% of groundwater withdrawn) and industry (20%). These vulnerable resources are found in glacial deposits or bedrock of previously glaciated regions in Canada and around the world. Managing and protecting water wells requires a robust geological model that identifies the geometry of hydraulically relevant features at the well field or contaminant plume scale. Creating this type of model is challenging in previously glaciated settings, where texture is not the primary driver controlling groundwater flow or contaminant pathways. The last glaciation had a profound impact not only on texture, but also on the variable distribution of subsurface materials, the surface topography, and the underlying bedrock surface. In addition, the permeability of bedrock was affected through fracture and dissolution feature or karst development associated with crustal rebound and glacial and post-glacial hydraulics. This geological history plays a key role in determining modern contaminant pathways and plume evolution, volume and depth of aquifers, integrity of aquitards, and consequently, flow system characteristics, well productivity and susceptibility to contamination. While geological surveys and the environmental sector have made strides in creating regional scale models, the heterogeneity of glacial deposits at the well field scale remains a challenge.******The proposed research addresses this by 1) identifying typical sedimentation styles or architecture in specific glacial settings, and assessing its influence on water quality; and 2) examining the interactions between glacial processes and the underlying bedrock and how this has impacted karst distribution in bedrock aquifers. Numerous high-resolution core and water quality data will be examined to test if certain landscapes and subsurface sediment profiles are more susceptible to contamination than others, thus improving delineation of wellhead protection areas. The relationship between glacial processes and bedrock will be explored by examining a) the geological evolution of a buried bedrock valley and its relationship to the occurrence of productive karstic bedrock aquifers and b) the geological properties of the sediment-bedrock interface to shed light on subglacial processes and to assess if there are any predictive relationships useful for subsurface modelling and protection of contact aquifers.******Research findings and 5 graduates with the much-needed skills of applying glacial geology to hydrogeology will have a significant impact on Canada's ability to protect groundwater at the well-field scale, by advancing our understanding of the geological history of these previously glaciated landscapes.