Soil Moisture Movement by Temperature Gradient

Results from a one-dimensional analytical model and experiments showed that redistribution of moisture due to temperature gradients was maximum when initial saturation was about 20%. Increase in moisture at the cold end was then on the order of 0.03 g/cm³ or 1.2% by weight, after 3 days at a temperature gradient of 0.9°C/cm and about 80% of this in the first day. At low moisture content the adsorbed water is held firmly relative to diffusion due to vapor concentration gradient and only insignificant redistribution takes place. A layer of fine initially dry material would absorb water until all the adsorbed water requirements are satisfied. Since the vertical movement of moisture due to temperature gradients was found to be insignificant, any buildup of moisture in the basecourse must result from other causes, either seepage through the top seal or lateral movement. For lateral movement, temperature gradients could be important because movement from berms under the cooler seal at nighttime is followed by movement vertically down during the day, possibly leading to eventual moisture accumulation.