Unsaturated hydraulic conductivity in porous media: Percolation theory

The unsaturated hydraulic conductivity is an important property of porous media whose estimation is still investigated. In this study, we developed a new unsaturated hydraulic conductivity model from applying percolation theory to the pore–solid fractal approach (PSF). In actual applications the pore size distribution was obtained from the soil water retention curve. Using 104 soil samples from the UNSODA data base, the new developed unsaturated hydraulic conductivity model was compared with the Mualem's approach combined with water retention models of van Genuchten and PSF. The calculated root mean square error (RMSE) for the new model developed in this study, vG-M and PSF-M models was 0.69, 0.91 and 0.83 cm day− 1, respectively. The results showed that percolation theory model estimated unsaturated hydraulic conductivity curve better than the vG-M and PSF-M models especially at high water contents.

► We proposed a more general hydraulic conductivity model.
► The developed model was compared to two other models.
► Our model estimated conductivity better than other models.
► All models underestimated conductivity at low water contents.