Thermally Induced Water Transfer in Salinized, Unsaturated Soil
- I. N. Nassar,
- Robert Horton and
- A. M. Globus
Natural soil surfaces are exposed to nonisothermal conditions. Resulting thermal gradients cause water to redistribute. The combined effects of solute concentration and temperature gradient on water transfer has not been fully studied. In this work, a model describing the simultaneous transfer of heat, water (liquid and vapor), and solute in porous media was used to predict water transfer under different initial solute concentrations and mean temperatures in closed soil columns. The initial solute concentrations ranged from 0.0 to 3.085 mol kg−1, and mean soil temperatures ranged from 17 to 37°C with thermal gradients of 100°C m−1. The predicted water contents were compared with observed values obtained from soil column experiments. Both the predicted and observed values of water content showed accumulation of water at the cold ends of the soil columns. The predicted and measured net water transfer decreased nonlinearly as the solute concentration increased. Net water transfer increased as the mean temperature increased. Both the predicted and measured solute concentrations showed an increase at regions close to the hot end of the soil columns. The soil column with initial water content of 0.232 m3 m−3 had a large accumulation of solute at the hot end relative to columns with 0.132 or 0.072 m3 m−3 initial water contents. This suggested that water moved mostly in liquid form under the initial water content of 0.232 m3 m−3, whereas it moved primarily in vapor from under initial water content of 0.072 m3 m−3.
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