Groundwater Connection between Glaciers and Streams under a warming Climate

冰川融化在地下水补给和随之而来的地下水排入溪流中的作用往往被忽视。冰川融化的水渗入土壤，并返回到下坡的溪流中。当地下水是河流的主要水源时，这些过程可以在维持溪流流动方面发挥关键作用。在冰川流域变暖的情况下，地下水对径流的贡献可能会越来越重要。更好地了解径流的季节性和长期变化，将改善对冰川融化如何影响下游水文和生态系统的预测，并为水管理提供信息。这个项目考察了融化的冰川和山间溪流之间的地下水联系。最重要的问题是：地下水在连接融化的冰川和山区分水岭的溪流方面起到了什么作用？这项研究对气候变化中的水资源管理有直接的影响。这个项目是科罗拉多大学博尔德分校和萨利什·库特奈学院的合作项目，该学院有75%的美洲原住民学生。通过有计划的研究和指导活动，该项目将为来自不同背景的学生提供教育和专业发展的机会，并向美洲原住民社区提供服务。近几十年来，冰川集水区的溪流在夏末至冬季期间有所增加，此时流向溪流的地表径流最少。据推测，冰川融化增加了对地下水的补给，含水层因冻土融化而更具渗透性，因此向溪流排放的地下水增加。从长远来看，这种向溪流排放地下水的做法是不可持续的，因为融化的冰川可能会消失。三个具体的研究问题是：(1)冰川融水在时间和空间上如何与径流相关？(2)随着含水层经历季节性冻结和融化以及冻土的长期退化，气候变化如何影响含水层的渗透性？(3)受冰川融水影响的地下水和溪流的变化如何影响下游生态系统？为了解决这些问题，该项目有三项主要任务：(1)描述科罗拉多州和蒙大拿州两个具有代表性的冰川流域的特征，这两个流域有共同之处，但在规模和水文条件上不同；(2)分析相关数据，重点是气温、冰川融化、水流、地下水位和水温；(3)综合数据并进行耦合热传输和水流的数值模拟。这些任务将在现场和实验室环境中进行。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The role of melting glaciers in groundwater replenishment and consequent groundwater discharge to streams is often overlooked. Glacier meltwater seeps into soils and emerges back into downslope streams. These processes could play a critical role in sustaining streamflow when groundwater is the main source of water for the streams. Under warming in watersheds with glaciers, groundwater can be an increasingly important contributor to streamflow. Better understanding of seasonal and long-term variations in streamflow will improve predictions of how melting glaciers impact downstream hydrology and ecosystems and inform water management. This project examines the groundwater connection between melting glaciers and mountain streams. The overarching question is: What is the role of groundwater in connecting melting glaciers to streamflow in mountain watersheds? This study has direct implications for water resource management in a changing climate. This project is a collaboration between University of Colorado Boulder and Salish Kootenai College, which has 75% Native American students. Through planned research and mentoring activities, this project will provide opportunities for education and professional development of students from a diverse background and for outreach to Native American communities.Streamflow in glacierized watersheds has increased in recent decades during late summer to winter when surface runoff to streams is minimal. It is hypothesized that melting glaciers enhanced recharge to groundwater, aquifers are more permeable because of thawing frozen ground, and consequently groundwater discharge to streams increases. In the long run, such groundwater discharge to streams cannot be sustained as melting glaciers may disappear. Three specific research questions are: (1) How does glacier meltwater correlate to streamflow temporally and spatially? (2) How does a changing climate affect aquifer permeability as aquifers undergo seasonal freezing and thawing and long-term degradation of frozen ground? (3) How do changes in groundwater and streams affected by glacial meltwater influence downstream ecosystems? To address these questions, the project has three main tasks: (1) Characterize two representative watersheds with glaciers in Colorado and Montana that share commonalities but are distinct in scales and hydrologic conditions; (2) Analyze relevant data focusing on air temperature, glacier melt, streamflow, groundwater levels, and water temperature; (3) Synthesize the data and conduct numerical modeling that couples heat transfer and water flow. These tasks will be carried out in both field and laboratory settings.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.