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

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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.