The unsaturated soil hydraulic properties (the soil water characteristic and relative permeability curves)
are key hydrodynamic parameters in the fields of soil science and civil engineering. Because of the strong
dependency of these properties on water content, their determination is subject to considerable
experimental and numerical problems. Difficulties increase when the soil approaches oven-dry
conditions, a situation often encountered in arid and semi-arid areas. Moreover, computational costs of
estimating the hydrodynamic properties can be relatively high also. After a short review of alternative
modeling approaches for the hydraulic functions from saturation to oven-dryness, we present a
theoretical-numerical approach, along with a relatively simple, robust and inexpensive experimental
method for inverse determination of van Genuchten/Mualem soil hydraulic parameters. For gravimetric
water contents greater than 0.04, numeral results agreed well with experimental data, while some
discrepancies were observed at very low water contents.