Over winter freeze-thaw events are notoriously difficult to represent in
hydrologic models and have serious implications for the hydrologic
function of intermittently freezing regions. With changing climate
leading to higher variability in observed weather patterns, it is
anticipated that mid-winter thaw events may become more numerous,
especially in cold regions. Midwinter thaw events are often the cause of
flooding due to the coupled impact of rain-on-snow, and limited soil
infiltrability. A numerically efficient, semi-analytical coupled thermal
and mass transport model is presented that is capable of representing
the ice content of near-surface soil. This model allows for rapid and
stable prediction of the ice content of frozen or partially frozen soil
without having to solve a discrete form of the coupled partial
differential equations. The model tracks pore ice formation and soil
cold content in terms of enthalpy. It is tested against data collected
in Southern Saskatchewan and is shown to reproduce field observations.
This model is efficient enough to be incorporated as a module into
existing regional hydrologic models and is expected to improve
predictions of over-winter streamflow and flooding potential.