Incorporating seasonal and extreme hydrologic events into groundwater recharge and vulnerability assessment

区域范围内地下水资源的安全和可持续性取决于制定切合实际的水源保护战略和对自然补给或补给的准确估计，事实证明，这一参数在区域范围内极难量化。瞬变水文条件对地下水脆弱性和补给的影响很少被考虑，但可能是最关键的控制参数之一。例如，季节气候变异性和极端水文条件，如主要降水事件和仲冬融雪期，可在年度循环过程中显著影响补给量的分布和数量。极端的水文变化也可能是将地表污染源引入地下的一个主要因素。这在农业景观中尤其明显和关键，因为农业景观中存在从营养溶质到胶体病原体的各种非点源。气候证据表明，这些类型的极端水文事件在加拿大和全世界的发生频率正在增加，这可能是由于气候变化的影响。这一拟议研究方案的主要目标是调查和量化季节性水文变化对区域地下水补给估计和水源脆弱性评估的影响。研究工作将涉及实地实验，以收集密集的综合数据集，以便能够量化整个年度气候循环过程中的补给和污染物质量通量，并利用新出现的模型进行数值分析，这些模型可以在三维框架内纳入瞬变水文复杂性，包括气候变异性、地下水-地表水相互作用以及可变饱和条件下的温度和污染物迁移。该研究计划的结果将立即对省和市当局在制定长期地下水管理和水源保护计划以及制定与新出现的地下水保护立法有关的土地使用管理的科学政策方面有所帮助。

The security and sustainability of groundwater resources at the regional scale depend on the development of realistic source protection strategies and accurate estimates of natural replenishment or recharge, a parameter that has proven to be extremely difficult to quantify at the regional scale. The influence of transient hydrologic conditions on groundwater vulnerability and recharge is rarely accounted for yet may represent one of the most critical controlling parameters. For example, seasonal climatic variability and extreme hydrologic conditions, such as major precipitation events and mid-winter snow melt periods, can significantly influence recharge distribution and magnitude over the course of an annual cycle. Extreme hydrologic variability can also represent a major factor in introducing surface sources of contamination into the subsurface. This is particularly evident and critical in agricultural landscapes where diverse non-point sources exist ranging from nutrient solutes to colloidal pathogens. Climatic evidence suggests that the frequency of occurrence of these types of extreme hydrologic events is increasing in Canada and worldwide, potentially due to the influence of climate change. The main objective of this proposed research program is to investigate and quantify the impact of seasonal hydrologic variability on estimates of regional groundwater recharge and source vulnerability assessment. The research work will involve field experimentation to collect dense, integrated data sets designed to permit the quantification of recharge and contaminant mass flux throughout the course of the annual climatic cycle and numerical analysis using emerging models that can incorporate transient hydrologic complexity including climatic variability, fully integrated groundwater-surface water interaction, and temperature and contaminant transport under conditions of variably saturation in a three dimensional framework. The results of the research program will be immediately useful to provincial and municipal authorities in developing long-term groundwater management and source protection plans and in establishing science-based policies governing land use management related to emerging groundwater protection legislation.