New pedotransfer function ("CRC") for the prediction of unsaturated soil hydraulic conductivity using soil water retention data

Several review articles have emphasized, that a comprehensive set of pedotransfer functions may be applied throughout a wide range of disciplines of Earth system sciences and are of great importance for land surface models. Most pedotransfer functions deducing soil hydraulic data from nonhydraulic soil data such as soil texture and bulk density, yield soil water retention predictions, but do not provide information concerning soil hydraulic conductivity. For this reason, a simple method was developed to estimate soil hydraulic conductivity using soil water retention information. Empirical equations are established to predict soil hydraulic conductivity from soil water retention information. These equations are relatively straightforward and do not require the fitting of nonlinear functions. Predictions of soil hydraulic conductivity using 106 soil samples indicates the reliable performance of the new method. The prediction quality of the new method was estimated from the calibration data set, which produced equivalent results to the Zacharias and Wessolek pedotransfer function, which were even better than the predictions obtained from the original Mualem-van Genuchten model, the Soto fractal model, and the pedotransfer function reported by Weynants and Vereecken. The stochastic structure of the calibration data reflects the presence of important soil structural properties, which are not represented by the soil water retention characteristics.