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Transient and Transition Factors in Modeling Permafrost Thaw and Groundwater Flow
Joelle E Langford1, Robert A Schincariol, Ranjeet M Nagare2
1Department of Earth Sciences, University of Western Ontario, 1151 Richmond Street, N6A 5B7, London, ON, Canada.
Ground Water
|May 14, 2019
Summary
Permafrost degradation is modeled using a 3D approach, revealing that transient simulations with unfrozen soil layers improve accuracy. Microtopography and talik development significantly influence permafrost thaw, crucial for infrastructure stability.
Area of Science:
- Geosciences
- Hydrology
- Climate Science
Background:
- Permafrost degradation impacts Northern Hemisphere infrastructure and ecosystems.
- Understanding groundwater and heat flow in permafrost is complex due to variable frozen zones.
- Characterizing permafrost thaw requires advanced modeling techniques.
Purpose of the Study:
- To develop and validate a 3D model for simulating permafrost degradation.
- To investigate methodologies for establishing accurate permafrost initial conditions for transient simulations.
- To assess the influence of microtopography and talik development on permafrost thaw.
Main Methods:
- A 3D model of a permafrost plateau and surrounding wetlands was created using FEFLOW and piFreeze.
- The Simultaneous Heat and Water (SHAW) model provided boundary conditions for ground temperature and surface water balance.
- Transient spin-up methodologies were compared to steady-state conditions for initializing permafrost models.
Main Results:
- Models initialized with transient spin-up, including an unfrozen layer, provided superior results compared to steady-state initial conditions.
- Land surface microtopography and talik development were identified as critical factors in permafrost degradation.
- The study highlights the importance of accurate initial conditions for simulating permafrost evolution.
Conclusions:
- Transient simulations are more effective for modeling permafrost degradation.
- Microtopography and talik development are key drivers of permafrost thaw.
- Accurate permafrost modeling can inform strategies for stabilizing degrading permafrost and protecting infrastructure.
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