Groundwater Connection between Glaciers and Streams under a warming Climate

冰川融化在地下水补充和随后地下水排入河流方面的作用往往被忽视。冰川融水渗入土壤，又流回下坡的溪流。当地下水是河流的主要水源时，这些过程可以在维持河流流量方面发挥关键作用。在有冰川的流域变暖的情况下，地下水可以成为越来越重要的河流流量贡献者。更好地了解径流的季节性和长期变化将有助于更好地预测冰川融化如何影响下游水文和生态系统，并为水资源管理提供信息。该项目研究了冰川融化和山溪之间的地下水联系。首要的问题是：地下水在连接冰川融化和山区流域的溪流方面起着什么作用？这项研究对气候变化中的水资源管理有直接影响。这个项目是科罗拉多博尔德大学和Salish Kootenai学院之间的合作，该学院有75%的美国土著学生。通过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职业发展机会，并与美洲土著社区进行外联。近几十年来，冰川流域的径流量在夏末至冬季增加，当时流向溪流的地表径流量很小。据推测，冰川融化增加了对地下水的补给，由于冻土融化，含水层更具渗透性，因此地下水向河流的排放增加。从长远来看，由于冰川融化可能会消失，这种地下水排入溪流的情况无法持续。三个具体的研究问题是：（1）冰川融水如何在时间和空间上与径流相关？(2)随着含水层经历季节性冻融和冻土长期退化，气候变化如何影响含水层渗透性？(3)受冰川融水影响的地下水和河流的变化如何影响下游生态系统？为了解决这些问题，该项目有三个主要任务：（1）描述科罗拉多和蒙大拿州两个有代表性的冰川流域，这两个流域有共同之处，但在规模和水文条件上有所不同：（2）分析相关数据，重点是气温，冰川融化，流量，地下水位和水温;（3）综合数据进行传热与水流耦合的数值模拟。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.