https://escholarship.mcgill.ca/concern/theses/44558k36w

In cold regions, the unfrozen water content plays an important role in a number of processes, including
permafrost thaw, groundwater-surface water exchange, and heat and solute transport in soils. The
relationship between unfrozen water content and sub-freezing temperatures (or suction at the ice-water
interface) is known as the soil-freezing characteristic curve (SFCC). Previous studies have shown that
considering the unfrozen water content can significantly improve accuracy in heat and water transport
modelling. However, the differences in how various soil-freezing functions and parameterizations affect
hydrogeologic properties and thermal regimes are not well understood. In this thesis, SUTRA-ice, a
numerical model that couples groundwater flow and energy transport with dynamic freeze-thaw processes,
is used to simulate and compare the performance and parameterization of three widely used SFCC functions
(exponential, piecewise linear, and power law). The shape of the SFCC is dependent on parameters including
the residual unfrozen water content, freezing point depression, or empirical constants characteristic of a
given soil. A two-dimensional homogeneous model with time-dependent thermal and hydrological surface
boundary conditions represents a simple permafrost cross-section. Results show that the type and
parameterization of the SFCC significantly affects permafrost evolution, active zone dynamics, and stream
discharge in coupled heat and water transfer modelling of frozen soil. Depending on the SFCC used, the
residual liquid water saturation and freezing point depression can control the level of ice saturation in the
model, talik and permafrost formation, as well as the thickness of the active layer.

https://escholarship.mcgill.ca/concern/theses/44558k36w