The role of groundwater in mountain hydrological systems under a changing climate

气候变化在高海拔地区进展迅速，全球山地积雪和冰川正在缩小，积雪融化时间提前，蒸散量（ET）增加，威胁着全球重要的山地径流和水资源。地下水最近被认为是山地水文系统的一个至关重要的组成部分，在冰雪储量下降的情况下，地下水有望帮助维持山地溪流的流动。然而，地下水并非不受气候变化的影响；气温、雨雪比例和植被格局的变化可能对山区地下水储量产生负面影响。我们为山区设计有效水资源管理策略的能力受到地下水观测数据异常稀缺、水文地质复杂性和山地地下水系统变化的不确定性的限制。这项研究计划的总体目标是提高对全球山区地下水和地表水过程的认识，并预测未来的变化，为水资源管理提供信息。将在今后五年内实现两个中期目标。首先，将开发非常规数据源（如地下水泉、湿地井）并将其纳入野外监测和数值模拟，以克服数据限制，提高山地地下水系统的观测能力。新的综合观测和建模方法将在新斯科舍省布雷顿角高地国家公园一个相对容易接近的地方进行测试，以调查地下水补给来源和变化。第二，构建包括观测井、地下水泉和湿地井在内的全球山地地下水野外数据集。将对这些数据进行统计分析，以确定趋势，并与现有的全球数据集相结合，以确定关键的脆弱性因素（例如，地形、地质、气候）。基于新的全球数据集，将开发三维地下水流量数值模型，并应用气候预估来阐明未来山区地下水储存损失及其对水资源管理的影响。培养8名高素质人才（博士2名，硕士2名，本科生4名）。这项研究计划将扩大我们测量、模拟和管理山地地下水的能力，这是一种隐藏的、未被充分研究的、但至关重要的水资源。这是首次评估不同地理环境下山区地下水系统的大规模变化，以揭示新趋势和预测未来影响。这项工作将为气候变化适应战略的设计提供信息，并有助于改善山区下游19亿人口的饮用水、农业、水电和工业用水管理。

Climate change is progressing rapidly at high elevations such that mountain snowpack and glaciers are shrinking globally, snowmelt is occurring earlier in the year and evapotranspiration (ET) is increasing, threatening globally important mountain runoff and water resources. Groundwater has recently been recognized as a critically important part of mountain hydrological systems and it is expected to help sustain mountain streamflow as snow and ice storage declines. However, groundwater is not immune to the impacts of climate change; changing air temperatures, snow/rain fraction and vegetation patterns may negatively impact mountain groundwater storage. Our ability to design effective water resource management strategies for mountain regions is limited by exceptionally scarce observational data of groundwater, hydrogeologic complexity and uncertainty around how mountain groundwater systems are changing. The overall goal of this research program is to improve understanding of linked groundwater and surface water processes in mountain regions globally and project future changes to inform water resource management. Two medium-term objectives will be tackled over the next five years. First, unconventional data sources (e.g., groundwater springs, wetland wells) will be developed and incorporated into field monitoring and numerical modeling to overcome data limitations and improve observational capacity of mountain groundwater systems. New integrated observational and modelling approaches will be tested at a local, relatively accessible field site in the Cape Breton Highlands National Park, Nova Scotia, to investigate groundwater recharge sources and variability. Second, a global dataset of mountain groundwater field data will be compiled, incorporating observation wells, groundwater springs and wetland wells. This data will be statistically analysed for trends and combined with existing global datasets to identify key vulnerability factors (e.g., topography, geology, climate). Based on the new global dataset, three-dimensional groundwater flow numerical models will be developed, and climate projections will be applied to elucidate future mountain groundwater storage loss and the consequences for water resource management. 8 Highly Qualified Personnel (2 PhD, 2 Master's and 4 Undergraduate students) will be trained as part of this research. This research program will expand our ability to measure, model and manage mountain groundwater, a hidden, understudied, yet critical water resource. It constitutes the first effort to assess large-scale changes in mountain groundwater systems across different geographic settings to reveal emerging trends and project future impacts. This work will inform the design of climate change adaptation strategies and contribute to improved water management for drinking water, agriculture, hydropower and industrial use for the 1.9 billion people in the world who live downstream of mountains.