Collaborative Research: RUI: Zero-order to first-order: Hydrologic drivers of surface-subsurface storage dynamics in thawing permafrost landscapes

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。北极的液态水在被称为永久冻土的冻土表面或其附近流动。随着永久冻土的融化，水沿着新的路径流动，调动了以前冻结的碳。如果永久冻土解冻并干燥，碳的释放速度是永久冻土解冻并保持饱和的三倍，这意味着水模式部分控制了碳的释放。然而，人们对永久冻土饱和的模式或驱动因素以及它们如何随气候变化仍知之甚少。这项研究将使用野外测量、遥感和建模来调查阿拉斯加北坡山坡饱和模式的动力学、驱动因素和敏感性。结果将有助于为整个南部阿巴拉契亚山脉和爱达荷州的农村K-12学生和社区创建“H2cOld: Water in Arctic”旅行推广活动。该项目还将为科学事业培养四名本科生和一名研究生。在连续的永久冻土层下，北极山坡的水文很大程度上是由水道控制的，季节性饱和的零级特征排水了北极高地的三分之一。水迹可以迅速退化成热侵蚀沟渠，这是北极最常见的热侵蚀特征，改变了季节性饱和度和水、营养物质和沉积物的通量。尽管水道和热侵蚀沟渠是永久冻土碳释放的最大和最多变的水生来源，但它们的饱和动力学以及这些动力学如何随着永久冻土融化而变化，人们仍然知之甚少。假设这两个特征代表了北极山坡水文地表网络范围的末端成员，它们具有不同的饱和模式，随着气候变暖而分化。该研究项目将在阿拉斯加北部成对的水道和热侵蚀沟渠中通过遥感和实地活动来验证这一假设，以校准具有可变饱和度和冻融能力的水能输送模型。总的来说，这项工作将改善对北极饱和控制碳释放的预测。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。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Liquid water in the Arctic flows at or near the surface above frozen ground known as permafrost. As permafrost thaws, water flows along new paths, mobilizing previously frozen carbon. If permafrost soils thaw and dry, carbon is released three times more readily than if permafrost soils thaw and remain saturated, implying that water patterns partially control carbon release. Yet, the patterns or drivers of permafrost saturation and how they vary with climate remain poorly understood. This research will use field measurements, remote sensing, and modeling to investigate the dynamics, drivers, and sensitivity of hillslope saturation patterns on the North Slope of Alaska. Results will help to create an ‘H2cOld: Water in the Arctic’ traveling outreach activity for rural K-12 students and communities throughout the southern Appalachians and Idaho. The project will also train four undergraduate students and a graduate student for science careers.The hydrology of Arctic hillslopes underlain by continuous permafrost is largely controlled by water tracks, seasonally saturated zero-order features draining a third of the upland Arctic. Water tracks can rapidly degrade into thermoerosional gullies, the most common Arctic thermoerosional feature, altering seasonal saturation and fluxes of water, nutrients, and sediments. Although water tracks and thermoerosional gullies are the largest and most variable aquatic sources of permafrost carbon release, their saturation dynamics and how these dynamics change as permafrost thaws remain poorly understood. These two features are hypothesized to represent endmembers of the surface network extent of Arctic hillslope hydrology with distinct saturation patterns that are diverging as the climate warms. This research project will test this hypothesis in paired water tracks and thermoerosional gullies in northern Alaska via remote sensing and field campaigns to calibrate a water-energy transport model with variable saturation and freeze-thaw capabilities. Collectively, this work will improve predictions of saturation-controlled carbon release from the Arctic.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.