New Approach for Estimating Hydraulic Properties of Soils in Cold Regions

One of the arduous tasks in cold regional studies is estimating soil hydraulic properties, such as soil freezing characteristics and hydraulic conductivity, which are important when studying transport process in frozen soils. Costly data collection methods and existing isothermal models are limitations in understanding soil water dynamics in frozen soils. Pedotransfer functions have become a hot topic in the earth- and environmental-related sciences to predict soil physical and chemical properties easily, routinely, or cheaply for a specific non-frozen geographical region. Based on similarity between wetting and freezing processes in soil, we presented a new approach to derive soil freezing characteristics from soil water characteristics of non-frozen soils using existing pedotransfer functions. We considered a conventional soil water characteristic model and existing pedotransfer functions for determining the relationships; unfrozen water content vs. subzero temperature, and hydraulic conductivity vs. subzero temperature using Clapeyron equation. The proposed approach successfully predicted unfrozen water content and hydraulic conductivity for different soils when compared with those reported in the literature. Furthermore, effect of soil bulk density (porosity) on unfrozen water content and hydraulic conductivity at different subzero temperatures was discussed for range of soils.