ASSESSMENT OF VARIOUS METHODS FOR THE DETERMINATION OF HYDRAULIC CONDUCTIVITIES OF TWO GREEN ROOF SUBSTRATES BY STEADY STATE INFILTRATION EXPERIMENTS

The unsaturated hydraulic conductivity as a function of water content, K(theta), of two substrates used in green roofs was calculated, using the equations of Jackson (1972), van Genuchten (1980) and Valiantzas (1989). The comparison of the three calculated functions of K(theta) with experimental data was done in an indirect way. The steady state water profiles, with constant infiltration rate of 5.5 x 10(-6) ms(-1), were calculated using the three above-mentioned different K(theta) for each substrate. These profiles were compared to the experimental steady state water profiles shaped after the application of a constant rainfall of 5.5 x 10(-6) ms(-1) in the laboratory. The comparison between the calculated and the experimental water profiles showed that the above-mentioned equations can be used for the calculation of K(theta) for low-depth substrates. The proposed method is a simple indirect method to compare the calculated K(theta) methods. Copyright (C) 2009 John Wiley & Sons, Ltd.