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 ( θ) , 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 ( θ ) with experimental data was done in an indirect way. The steady state water profiles, with constant infiltration rate of 5.5 × 10 −6  m s −1 , were calculated using the three above‐mentioned different K ( θ ) 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 × 10 −6  m s −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 ( θ ) for low‐depth substrates. The proposed method is a simple indirect method to compare the calculated K ( θ ) methods. Copyright © 2009 John Wiley & Sons, Ltd.