Estimation of Soil Hydraulic Properties from Numerical Inversion of Tension Disk Infiltrometer Data

Many applications involving variably saturated flow and transport require estimates of the unsaturated soil hydraulic properties. Nu-merical inversion of cumulative infiltration data during transient flow, complemented with initial or final soil water content data, is an in-creasingly popular approach for estimating the hydraulic curves. In this study, we compared Mualem–van Genuchten (MVG) soil hydraulic parameters obtained from direct laboratory and in situ unsaturated hydraulic conductivity measurements with estimates using numeri-cal inversion of tension infiltration data of four coarse- to medium-textured soils in Alentejo (Portugal). The laboratory methods used were suction tables, pressure plates, and the evaporation method as applied to undisturbed soil samples collected from the surface horizons of four different soil profiles. Field measurements were taken with a tension disk infiltrometer using consecutive supply pressure heads o