ABSTRACT
Since thermodynamic similarity exists between freezing and drying, i.e., both are functions of pore size, it is often assumed that for similar liquid water contents, the hydraulic conductivity of a frozen soil and an unfrozen soil will also be similar.[4] Models that employ this assumption sometimes overestimate water movement during freezing, leading some to posit additional, unspecified impedance to unsaturated flow in frozen soil.[5] Conclusive data remain elusive, due primarily to experimental difficulties, but some generalizations are possible. Coarse-textured, sandy soils, when unfrozen, generally have high saturated hydraulic conductivities, but since their pores drain at gauge pressures close to zero their conductivities decrease dramatically with desaturation. Finer textured soils generally have lower saturated hydraulic conductivities, but since the decrease in water content with declining pore water pressure is more gradual, their conductivities decrease more slowly, so that they can often sustain more water movement in the frozen state than sandy soils. For this reason, they are more prone to redistribution and frost heave during freezing.
