CAREER: Follow the Water: Understanding River Discharge Dynamics in Rapidly Changing High Northern Latitudes

随着平均气温、降雨量、冰川和冰盖融化速度以及永久冻土深度的增加，北极地区正在迅速变化。然而，这些过程之间的联系以及它们如何影响北极河流中水的排放、来源和营养物质浓度还没有得到很好的了解。为了描述河流来源变化的特征并弥合这一知识差距，该项目将测量格陵兰一系列冰川覆盖（包括无冰川覆盖）的永久冻土流域水循环的多个组成部分。模型将检验这样一个假设，即在未来更温暖、更湿润的北极，流经地面的水流对河流的贡献将会增加，并在该季节的后期持续存在，这将有助于抵消因冰块稳步减少而导致的河水损失。通过与阿拉斯加本土科学与工程项目、格陵兰研究机构、哈佛大学贝尔弗中心北极倡议、格陵兰当地社区和北极大学Læra研究所合作，将研究和教育结合起来，开发一个强大的平台，增加阿拉斯加和格陵兰本土学生对水文学的参与。该平台包括为阿拉斯加原住民和格陵兰学生提供格陵兰实地研究机会以及开发以北极水循环为重点的课程等项目。在过去的一百万年里，三个重要的水文变化与温暖湿润的高北极格陵兰岛有关：1)冰川融化带来的淡水增加；2)活动层加深（多年冻土融化）；3)降水增加。当前的气候变化正导致北极格陵兰岛更像过去的环境。北极变暖可能会增加活动层的深度，再加上北极预计会有更多的降雨，可能会导致更多的流量通过活动层，从而形成河流流量，但这一点尚不清楚。该项目将测量格陵兰高北极地区一系列冰川覆盖（包括无冰川覆盖）的永久冻土流域水循环的多个组成部分。这些数据将描述河流来源变化的特征，并提供校准新的数值水文模型所需的关键现场数据。然后，这些模型将帮助测试河流流量假设，假设未来北极在不同气候情景下的变化（例如，降水更多，活动力层更深）。这些分析将有助于理解活动层流量的增加如何减轻冰川衰退和未来向无冰流域过渡的水文影响。该项目将支持研究生和本科生，并开发一个强大的多方面平台，以增加阿拉斯加和格陵兰土著学生在STEM领域的参与。一门新的以北极为重点的水文学课程将通过远程授课，并利用关系将阿拉斯加和格陵兰的土著学生聚集在一起。该项目还将为阿拉斯加和格陵兰土著本科生提供在与研究人员合作的同时在实地共同学习的变革性体验。更大的社会效益包括了解北极水循环是如何变化的，这可能影响全球水循环、淡水资源和地球上的气候模式。该奖项反映了美国国家科学基金会的法定使命，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 Arctic region is rapidly changing as average air temperatures, rainfall, glacier and ice sheet melt rates, and permafrost depths all increase. However, the connections between these processes and how they influence the discharge, source, and nutrient concentrations of water in Arctic rivers are not well understood. To characterize shifting river source contributions and bridge this knowledge gap, this project will measure multiple components of the water cycle in permafrost watersheds across a range of glacial coverages (including glacier free) in Greenland. Models will test the hypothesis that in the warmer and wetter future Arctic, contributions from flow through the ground to the river will both increase and persist later in the season, which will help offset the loss of river water from steadily decreasing ice masses. Research and education are integrated by collaborating with the Alaska Native Science and Engineering Program, research institutions in Greenland, the Belfer Center’s Arctic Initiative at Harvard University, local Greenland communities, and the University of the Arctic Læra Institute to develop a powerful platform that increases Indigenous Alaskan and Greenland student participation in hydrology. This platform includes programs like Greenland field research opportunities for Indigenous Alaskan and Greenland students and development of Arctic water cycle focused courses. Three important hydrological shifts associated with a warmer and wetter High Arctic Greenland occurred within the last million years: 1) increased freshwater from glacier melt; 2) deepening active layer (permafrost thaw); and 3) increased precipitation. Current climate changes are leading to an Arctic Greenland more like these past environments. A warmer Arctic will likely increase active layer depths, which when coupled with greater rain expected in the Arctic, could result in more flow through the active layer contributing to river discharge, but this remains unknown. This project will measure multiple components of the water cycle in permafrost watersheds across a range of glacial coverages (including glacier free) in High Arctic Greenland. These data will characterize shifting river source contributions and provide critical field data needed to calibrate novel numerical hydrological models. These models will then help test river discharge hypotheses given future Arctic change under different climate scenarios (e.g., more precipitation, deeper active layer). These analyses will help understand how increased active layer flow could mitigate the hydrological impact of glacier recession and future transition to ice-free watersheds. This project will support graduate and undergraduate students and develop a powerful multifaceted platform to increase participation in STEM fields of Indigenous Alaskan and Greenland students. A new Arctic focused hydrology course will be taught via distance delivery and leverage relationships to bring together Indigenous Alaskan and Greenland students. This project will also provide Indigenous Alaskan and Greenland undergraduate students with a transformative experience learning together in the field while working with researchers. Larger societal benefits include understanding how the Arctic water cycle is changing, which can impact the global water cycle, freshwater resources, and climate patterns across Earth.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.