Analysis of solute redistribution in heterogeneous soil .1. Geostatistical approach to describe the spatial scaling factors

The soil water retention curve (WRC) and the saturated hydraulic conductivity (K-s) were measured in three overlying horizons in a vertical soil profile. The spatial variability in WRC and K-s was described with two separate sets of scaling factors, i.e., alpha(r,psi) and alpha(r,K) for WRC and K-s respectively. Both sets of scaling factors were found to be lognormally distributed. The log(c)-transformed scaling factors exhibited stationarity in their variance but showed non-stationarity in their median, both in vertical and horizontal direction. The trends or large scale deterministic variations were successfully removed using a median polish algorithm. The large scale variations contributed significantly to the total observed variability for the alpha(r,psi) parameters of the C2 horizon and for the alpha(r,K) parameters of the Ap horizon. Spatial structure for scaling parameters was only observed in these two cases, whereas a pure nugget was observed in all other cases.