Residual saturation defined ad hoc by Brooks & Corey, 1964 as given in [16]



Time elapsed



Time at the final stage of percolation


(T), (Ti)

Temperature, (i) denotes the initial phase



Time at the initial stage of percolation



Time at the beginning of the ponding stage of percolation



Percolation depth (vertical)/wetting front/heat transfer length (vertical)/membranes penetration depth



Water volume



Volume of the bulk soil or massive soil (control volume)



Vertical percolation velocity defined as the percolation that occurs in the vertical direction



Vertical distance/penetration depth/wetting depth/penetration depth at saturation state