Water movement in soil freezing and thawing cycles and flux simulation

One dimensional and two dimensional field experiments were conducted to investigate soil water flux in frozen soil, based on tracer concentration changes and water balance analysis. A capillary bundle model was developed to incorporate the Hangen-Poiseuille law into the flow analysis in frozen soil. The model demonstrated how the soil water flux changes as function of liquid soil water content and hydraulic conductivity. Results showed that the effect of water potential and temperature gradient caused liquid water to accumulate near the freezing front to form the maximum water flux. Water flux was influenced by the intermediate frozen soil layer blockage and groundwater movement during the thawing of soil from two directions: the surface downward and the bottom upward. The capillary bundle model well described water flow in the frozen soil under various temperature conditions and was a useful tool to characterize water movement in the water-ice and soil system.