Observations of soil freezing and frost heave at Inuvik, Northwest Territories, Canada

Field observations of soil temperature, moisture regime, and frost heave in silty clay hummocks at Inuvik, Northwest Territories, over the fall and early winter reveal that a significant amount of moisture migration and frost heave occurs within frozen soil at temperatures down to −2.4°C. The field data are analysed using thermodynamic considerations, and the apparent hydraulic conductivity is determined as a function of negative temperature. The conductivity falls from near 7 × 10 −9 m s −1 above 0 °C to about 3.5 × 10 −12 m s −1 at −1 °C, then remains fairly constant down to −2.4 °C. The observed decrease in heave with time is explained in terms of a diminishing water supply at the base of the active layer.