Comparison of different measuring and calculating methods to quantify the hydraulic conductivity of unsaturated soil

The double-plate method and the evaporation method provide comparable results on the hydraulic conductivity of soil (K(h_s)). Adaptation of the water retention curve according to the method of Vachaud and Vauclin proved to be very reliable. The course of the K(h_s) function is well shown by all indirect identification methods included in the comparison. In some cases, the absolute deviations of the measured from the calculated values are, however, considerable and primarily determined by the initial value of the hydraulic conductivity. In quantifying the capillary water rise, best approximation to the measured values was reached in 11 of 13 cases with the van Genuchten method.