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PI-Submitted Research Highlights for
Terrestrial Ecosystem Science Program

Arctic Greening Thaws Permafrost, Boosts Groundwater Flow

Elchin Jafarov

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January 2019

Models are used to understand how low-Arctic landscapes are changing in a warming climate.

The Science
Models of permafrost dynamics were used to show that snow drifts associated with tall shrub patches warm the underlying soil, resulting in holes called “through taliks” in the permafrost. Through taliks can activate deep flow pathways that significantly alter groundwater flow patterns in shrub-tundra landscapes.

The Impact
The resulting increases in groundwater discharge suggest that observed increases in tall shrub abundance throughout the Arctic may be a driver of observed increases in winter Arctic river discharge.

Summary
At hilly field sites in the southern Seward Peninsula, Alaska, patches of deep snow in tall shrubs are associated with higher winter ground temperatures. Reseachers from the Next-Generation Ecosystem Experiments (NGEE)–Arctic study show that through taliks—thawed zones extending through the entire permafrost layer—can form under these patches. The formation of through taliks creates new hydrologic pathways connecting the near surface to deeper regions, with significant hydrological and biogeochemical consequences. In particular, through taliks enable exchange and transport of nutrients and soil carbon from shallow upland hillslope sources to streams and lakes through groundwater discharge. To better understand the processes controlling and consequences of through taliks, researchers used NGEE–Arctic’s permafrost hydrology model, Arctic Terrestrial Simulator (ATS), to simulate through taliks associated with snow drifts. Scenarios were developed based on an intensively studied hillslope transect on the southern Seward Peninsula. In these scenarios, when through taliks formed, subpermafrost groundwater flow greatly increased. The simulations showed that through talik can form quickly (over a few decades) and then drive a rapid increase in subpermafrost groundwater.

Contacts
BER Program Manager
Daniel Stover
SC-23.1
Daniel.Stover@science.doe.gov (301-903-0289)

Principal Investigators
Elchin Jafarov
Los Alamos National Laboratory
Los Alamos, NM 87545
elchin@lanl.gov

Ethan Coon
Oak Ridge National Laboratory
Oak Ridge, TN 37831
coonet@ornl.gov

Funding
This work is part of the Next-Generation Ecosystem Experiments (NGEE)–Arctic project, which is supported by the Office of Biological and Environmental Research within the U.S. Department of Energy (DOE) Office of Science.

Publications
Jafarov, E.E., E.T. Coon, D.R. Harp, C.J. Wilson, S.L. Painter, A.L. Atchley, & V.E. Romanovsky. “Modeling the role of preferential snow accumulation in through talik development and hillslope groundwater flow in a transitional permafrost landscape." Environmental Research Letters 13(10), 105006 (2018). [DOI:10.1088/1748-9326/aadd30].

Related Links
NGEE Arctic

Los Alamos National Laboratory, Oak Ridge National Laboratory, Next Generation Ecosystem Experiment, NGEE-Arctic. Software: Advanced Terrestrial Simulator developed through Los Alamos National Laboratory LDRD funding and DOE BER NGEE-Arctic funding. 

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