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Title: Thermal effects of groundwater flow through subarctic fens: A case study based on field observations and numerical modeling

Modeling and observation of ground temperature dynamics are the main tools for understanding current permafrost thermal regimes and projecting future thaw. Until recently, most studies on permafrost have focused on vertical ground heat fluxes. Groundwater can transport heat in both lateral and vertical directions but its influence on ground temperatures at local scales in permafrost environments is not well understood. In this paper, we combine field observations from a subarctic fen in the sporadic permafrost zone with numerical simulations of coupled water and thermal fluxes. At the Tavvavuoma study site in northern Sweden, ground temperature profiles and groundwater levels were observed in boreholes. These observations were used to set up one- and two-dimensional simulations down to 2 m depth across a gradient of permafrost conditions within and surrounding the fen. Two-dimensional scenarios representing the fen under various hydraulic gradients were developed to quantify the influence of groundwater flow on ground temperature. Our observations suggest that lateral groundwater flow significantly affects ground temperatures. This is corroborated by modeling results that show seasonal ground ice melts 1 month earlier when a lateral groundwater flux is present. Further, although the thermal regime may be dominated by vertically conducted heat fluxes during most ofmore » the year, isolated high groundwater flow rate events such as the spring freshet are potentially important for ground temperatures. Finally, as sporadic permafrost environments often contain substantial portions of unfrozen ground with active groundwater flow paths, knowledge of this heat transport mechanism is important for understanding permafrost dynamics in these environments.« less
 [1] ;  [2] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [1]
  1. Stockholm Univ. (Sweden). Dept. of Physical Geography. Bolin Center for Climate Research
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computational Earth Sciences
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change Science Inst. and Environmental Sciences Division
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC05-00OR22725; LDRD201200068DR; 60-1626/2009; 362-1593/2013
Accepted Manuscript
Journal Name:
Water Resources Research
Additional Journal Information:
Journal Volume: 52; Journal Issue: 3; Journal ID: ISSN 0043-1397
American Geophysical Union (AGU)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); Los Alamos National Lab. (LANL) (United States); Swedish Geological Survey (SGU) (Sweden); Swedish Society for Anthropology and Geography (Sweden); Bolin Center for Climate Research (Sweden)
Country of Publication:
United States
58 GEOSCIENCES; 97 MATHEMATICS AND COMPUTING permafrost; thermal hydrology; modeling