Fig. 1. A comparison of the van Genuchten parameterization for K with the critical path analysis prediction for K. The latter uses 
= 0.6, D = 2.81, and 
t = 0.1. The moisture content at which Eq. [6] is replaced by Eq. [9] is 0.154. The former uses = 0.6, m = 0.285714, and r = 0.1. Equation [13] for the water-retention curve relates S to the hydraulic head, h, to the –(3 – D) = –0.19 power, whereas the van Genuchten parameterization, with the condition m = 1 – 1/n, yields S
h–0.4 for large h.