where Se is the effective saturation, Ks (m day1) is the saturated hydraulic conductivity, us (L L1) and ur (L L1) are the saturated and residual water contents, respectively, n is a fitting parameter, and m = 1 1/n. Ks and water retention curves were obtained experimentally according to the methods of Klute (1986) and Klute and Dirksen (1986), respectively, for undisturbed soils sampled using 0.1-L cores. Based on the water retention curve (Fig. 1), pressure heads were calculated from volumetric soil water