Frost heaving

Frost heave is optionally accounted for (see switch FrostSwelling) in a simplistic way provided that frost interaction has been chosen. A soil compartment will heave if the total volume of ice and unfrozen water exceeds the porosity of the soil in one layer.

During a situation when the soil tends to swell, the thickness of a compartment is calculated as:

                                  (1.38)

where ∆z^* is the orginal thickness of the layer, f_l ,f_i and f_s is the volumetric fractions of liquid water, ice and solids respectively, as calculated from the original thickness of the layer. The p_ms coefficient represents the parameter that corresponds to the maximal allowed swelling.

During shrinking the correspondent compartment size is calculated as:

                            (1.39)

where ∆z_t-1 is the compartment size for the previous time step and p_rf is the maximal shrinking rate parameter. See viewing function Shrinkage Function.