Hydraulic Conductivity in Frozen Unsaturated Soil Kunio Watanabe

Freezing experiments of silt and sand columns were carried out, and water and heat flows were observed. To estimate unsaturated hydraulic conductivity of soils, K(h), at above-freezing and subzero temperatures, Darcy’s law was solved under a non-isothermal condition with ice formation. K(h) steeply decreased with decreasing soil water pressure, h, and more gradually decreased with soil freezing. The results show that the hydraulic model, in which water content became constant under h<-105 cm, underestimated the K(h) of frozen soil, and suggest that the impedance factor, which reduced K(h) for frozen soil, is not necessary when accurate soil water and soil freezing characteristics are available. The hydraulic model, which can express two types of soil water flow, such as capillary and film flows, appears to be useful for expressing the hydraulic properties of soils under the freezing process