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Characterizing the Two‐Dimensional Thermal Conductivity Distribution in a Sand and Gravel Aquifer
Author(s) -
Markle Jeff M.,
Schincariol Robert A.,
Sass John H.,
Molson John W.
Publication year - 2006
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2005.0293
Subject(s) - thermal conductivity , aquifer , geology , plume , soil water , hydraulic conductivity , thermal conduction , mineralogy , thermal , soil science , geotechnical engineering , materials science , groundwater , thermodynamics , composite material , physics
Both hydrologic and thermal transport properties play a significant role in the movement of heat through permeable sedimentary material; however, the thermal conductivity is rarely characterized in detailed spatial resolution. As part of a study of the movement of thermal plumes through a sand and gravel aquifer, we have constructed a two‐dimensional profile of thermal conductivity. This work consisted of: (i) measuring the thermal conductivity of the soil solids, λ s , for the main stratigraphic units using the steady‐state divided‐bar apparatus and estimating conductivity from mineral composition; (ii) measuring the volumetric water content and porosity using crosshole ground‐penetrating radar; (iii) evaluating four models used to predict the apparent thermal conductivity, λ, of variably saturated soils and selecting the best model using the information‐theoretic approach, (iv) calculating the λ field on a 0.25‐m square cell grid using measured data and the selected model, and (v) simulating thermal transport within the two‐dimensional domain using a finite element numerical model. The apparent thermal conductivity in the saturated aquifer ranges from 2.14 to 2.69 W m −1 K −1 with a mean of 2.42 W m −1 K −1 Numerical simulations show that the heterogeneous thermal conductivity field results in increased thermal dispersion that is most pronounced at the plume front. Our values for λ and λ s may be used for glacial soils with similar mineralogy and texture. Our methods may also be used at other sites to construct the thermal conductivity distribution.