Transient and Transition Factors in Modeling Permafrost Thaw and Groundwater Flow.

Autor: Langford JE; Department of Earth Sciences, University of Western Ontario, 1151 Richmond Street, N6A 5B7, London, ON, Canada., Schincariol RA, Nagare RM; ARKK Engineering, #168 2301 Premier Way, T8H 2K8 Edmonton, AB, Canada., Quinton WL; Cold Regions Research Centre, Wilfrid Laurier University, 75 Avenue West, N2L 3C5 Waterloo, ON, Canada., Mohammed AA; Department of Geoscience, University of Calgary, 2500 University Dr. N.W., T2N 1N4 Calgary, AB, Canada.
Jazyk: angličtina
Zdroj: Ground water [Ground Water] 2020 Mar; Vol. 58 (2), pp. 258-268. Date of Electronic Publication: 2019 Jun 12.
DOI: 10.1111/gwat.12903
Abstrakt: Permafrost covers approximately 24% of the Northern Hemisphere, and much of it is degrading, which causes infrastructure failures and ecosystem transitions. Understanding groundwater and heat flow processes in permafrost environments is challenging due to spatially and temporarily varying hydraulic connections between water above and below the near-surface discontinuous frozen zone. To characterize the transitional period of permafrost degradation, a three-dimensional model of a permafrost plateau that includes the supra-permafrost zone and surrounding wetlands was developed. The model is based on the Scotty Creek basin in the Northwest Territories, Canada. FEFLOW groundwater flow and heat transport modeling software is used in conjunction with the piFreeze plug-in, to account for phase changes between ice and water. The Simultaneous Heat and Water (SHAW) flow model is used to calculate ground temperatures and surface water balance, which are then used as FEFLOW boundary conditions. As simulating actual permafrost evolution would require hundreds of years of climate variations over an evolving landscape, whose geomorphic features are unknown, methodologies for developing permafrost initial conditions for transient simulations were investigated. It was found that a model initialized with a transient spin-up methodology, that includes an unfrozen layer between the permafrost table and ground surface, yields better results than with steady-state permafrost initial conditions. This study also demonstrates the critical role that variations in land surface and permafrost table microtopography, along with talik development, play in permafrost degradation. Modeling permafrost dynamics will allow for the testing of remedial measures to stabilize permafrost in high value infrastructure environments.
(© 2019, National Ground Water Association.)
Databáze: MEDLINE
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