Fig. 2. Plot of the –D (porosity–fractal dimension) plane showing regions of validity for percolation scaling, using the criterion cross-over water content _x 0.9. Below the electrical conductivity, (), lines, scaling is valid for electrical conductivity; below the hydraulic conductivity, K(), line, scaling is valid for hydraulic conductivity. Blue lines represent the criteria in Eq. [18] and [19]; red represent the Balberg (1987) formulation.