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

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。北极的液态水在冻土或冻土表面或附近流动，称为永久冻土。随着永久冻土的融化，水沿着新的路径流动，动员了以前冻结的碳。如果永久冻土融化和干燥，碳的释放比永久冻土融化并保持饱和时容易三倍，这意味着水模式部分控制了碳的释放。然而，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然知之甚少。这项研究将使用现场测量、遥感和建模来调查阿拉斯加北坡山坡饱和度模式的动态、驱动因素和敏感性。这些成果将有助于为阿巴拉契亚山脉南部和爱达荷州的农村地区的K-12学生和社区创建一项名为“H2cOld：北极之水”的旅行推广活动。该项目还将为科学职业培训四名本科生和一名研究生。被连续多年冻土覆盖的北极山坡的水文在很大程度上受水迹控制，季节性饱和的零级特征耗尽了北极三分之一的高地。水迹可以迅速退化为热侵蚀冲沟，这是北极最常见的热侵蚀特征，改变了水、营养物质和沉积物的季节性饱和度和通量。尽管水迹和热蚀冲沟是永久冻土碳释放的最大和最多变的水生来源，但它们的饱和动态以及这些动态如何随着永久冻土融化而变化仍然知之甚少。这两个特征被假设为代表北极山坡水文地表网络范围的末端成员，具有不同的饱和模式，随着气候变暖而发散。这项研究项目将在阿拉斯加北部的成对水迹和热侵蚀沟壑中验证这一假设，方法是通过遥感和实地活动来校准具有可变饱和度和冻融能力的水-能量传输模型。总的来说，这项工作将改善对北极饱和控制碳排放的预测。这一奖项反映了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。

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.