FIG. 3. Relationship of (a) vs. _Y² and (b) n vs. _Y² for the total liquid retention curves for an air–water (data from Zhang et al., 2003) and air–NAPL–water system. , inverse macroscopic capillary length; n, pore-size distribution parameter; Y = ln(K_s) with K_s being the saturated hydraulic conductivity; _Y², variance of Y.