WATER AND SALT MOVEMENT IN UNSATURATED FROZEN SOIL - PRINCIPLES AND FIELD OBSERVATIONS

Soil temperatures, electrical conductivities, and water redistribution were measured at four field sites during a 30-day period in which the soil was never completely thawed. The soil on each site was a silt loam with varying aspects and vegetation covers. Both upward and downward flow of water and solutes were observed. Assuming that liquid water flow in frozen soil is analogous to unsaturated liquid flow in unfrozen soil, led to a simple equation that in general agreed with the field observations. Infiltration and frost heaving are discussed with respect to this simple theory. The liquid flow is so closely coupled with temperature that heat flow must be considered simultaneously in any comprehensive analysis. This coupling, as expressed in the simple liquid flow equation, accounts for the effect of soil water content on frost heave rates and the effects of temperature on maximum heaving pressures.