Impact of glaciation on groundwater vulnerability

随着人口增长、气候变化和污染物给地下水生产井带来压力，水源保护是当务之急。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，另外农业（60%的地下水被开采）和工业（20%）也大量使用地下水。这些脆弱的资源存在于加拿大和世界各地以前冰川地区的冰川沉积物或基岩中。管理和保护水井需要一个强大的地质模型，该模型可以识别井场或污染物羽流尺度上的水力相关特征的几何形状。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，在那里纹理不是控制地下水流动或污染物途径的主要驱动因素。末次冰期不仅对构造产生了深远的影响，而且对地下物质的变化分布、地表地形和下伏基岩表面也产生了深远的影响。此外，基岩的渗透率还受到断裂和溶蚀特征或与地壳回弹和冰期及冰期后水力学有关的岩溶发育的影响。这一地质历史在确定现代污染物路径和烟羽演化、含水层的体积和深度、含水层的完整性以及流动系统特征、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创建区域尺度模型方面取得了长足的进步，但井场尺度上冰川沉积物的异质性仍然是一个挑战。提出的研究通过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来解决这一问题；2)研究冰川过程与基岩之间的相互作用，以及这如何影响基岩含水层的喀斯特分布。将检查大量高分辨率岩心和水质数据，以测试某些景观和地下沉积物剖面是否比其他地区更容易受到污染，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检查a)埋藏基岩山谷的地质演化及其与生产性喀斯特基岩含水层的关系和b)沉积物-基岩界面的地质特性来探索，以阐明冰下过程，并评估是否存在任何对地下建模和接触含水层保护有用的预测关系。研究成果和5名具有将冰川地质学应用于水文地质学急需的技能的毕业生将通过推进我们对这些以前冰川景观的地质历史的理解，对加拿大在井场规模上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rely on groundwater for drinking and daily use, with additional significant use by agriculture (60% of groundwater withdrawn) and industry (20%).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.