GEOSTATISTIC INTERPOLATION OF SOIL-MOISTURE

The spatial distribution of soil moisture defines preferential flow pa ths in the unsaturated zone. Hence, three dimensional (3D) estimates o f soil moisture are of great importance to understand transport of con taminants as well as remediation processes in the unsaturated zone. In this study 3D estimates conditioned on spatially frequent observation s of soil moisture, have been obtained by kriging. The observations we re divided into subdomains consistent with the local stratigraphy, and directional semivariogram analysis was applied It was found difficult to clearly identify a 3D semivariogram function in this case, but fro m a georadar survey two semivariogram functions were derived. describi ng two different sedimentological units, By conditioning the estimates of soil moisture on the sedimentological architecture computed by ind icator kriging, more accurate estimates were achieved. These improveme nts were quantified by a 'jackknife' cross validation procedure. Besid es the practical aspects of finding the most important flow paths, est imates of soil moisture are valuable when validating unsaturated flow models.