Influence of Seasonal Hydrology on Watershed Dynamics and Groundwater Vulnerability

地下水资源的可持续性已成为一个全球范围的关切问题，特别是考虑到极端气候的增加和遗留污染物的影响。了解和适应这些不断变化的现实需要考虑流域规模的水文现象。传统的地下水水源保护策略受到挑战，将瞬态水文条件的影响和历史的土地利用实践的影响。现代数值模型是研究流域尺度区域地下水可持续性和脆弱性的主要工具。主要的挑战涉及这些模型的适当参数化和最大限度地减少结果的不确定性。特别具有挑战性的是地下水补给的可变性，它直接控制地下水库的补给和污染物的装载。季节性事件，包括高强度降水和积雪融化可以显着影响补给过程和他们的影响知之甚少。拟议的研究计划将包括三个主要组成部分。第一个是对安大略南部农村地区瞬时地下水补给的实地估算。这些资料将有助于深入了解地下水补给过程的瞬时性质以及不同水文、地质和地形条件下污染物的可变负荷模式。第二个组成部分将涉及将补给估计数纳入大规模的流域地下水-地表水综合模型。将进行模拟，以比较根据传统的补给估计技术和采用实测补给值的方法对农业非点源的区域污染物质量负荷、水平衡计算和捕获区动态进行预测估计的结果。总体而言，这项工作将说明的价值，提供现场测量的适用性和不确定性程度的区域尺度建模的补给估计。第三个组成部分是详细监测流域内季节性气候事件期间发生强烈短期补给现象的地点的近地表水文现象。这些类型的本地补给现象是具有挑战性的区域模型内捕获的结果可以提供有价值的信息，以加强区域建模工作和量化的公共供应井的脆弱性。总的来说，这项研究将提供关键的洞察控制补给现象和内在的不确定性的主要过程，并将有助于告知决策者谁是在重新审视整个加拿大的地下水源保护战略的过程中。

The sustainability of groundwater resources has become an issue of concern at a global scale particularly in light of increasing climatic extremes and the impact of legacy contaminants. Understanding and adapting to these changing realties is requiring consideration of hydrologic phenomena at the watershed scale. Conventional groundwater source protection strategies are challenged to incorporate the influences of transient hydrologic conditions and the influence of historical land use practices. Modern numerical models serve as primary tools to investigate regional groundwater sustainability and vulnerability at the watershed scale. Major challenges relate to the appropriate parameterization of these models and minimizing uncertainty in the results. Particularly challenging is the variability in groundwater recharge, which directly controls the replenishment of subsurface reservoirs and the loading of contaminants. Seasonal events including high intensity precipitation and snow melt can significantly influence recharge processes and their influence is poorly understood. The proposed research program will include three main components. The first involves field estimates of transient groundwater recharge throughout rural landscapes within southern Ontario. The information will provide insight into the transient nature of the groundwater recharge process and the variable loading patterns of contaminants under different hydrologic, geologic and topographic conditions. The second component will involve the incorporation of the recharge estimates into large scale, integrated groundwater-surface water models of the watersheds. Simulations will be conducted to compare the results of predictive estimations of regional contaminant mass loading from non-point agricultural sources, water balance calculations and capture zone dynamics based on conventional recharge estimation techniques and on an approach that incorporates measured recharge values. Overall, this work will illustrate the value of providing field measured estimates of recharge in the applicability and degree of uncertainty related to regional scale modeling. The third component involves detailed monitoring of near-surface hydrologic phenomena at locations within the watersheds where intense, short term recharge phenomena occur during seasonal climatic events. These types of local recharge phenomena are challenging to capture within a regional model and the results can provide information valuable to enhancing the regional modeling exercises and the quantification of public supply well vulnerability. Overall, the research will provide critical insight into the major processes controlling recharge phenomena and intrinsic uncertainty, and will help to inform policy makers who are in the process of re-examining groundwater source protection strategies across Canada.