Analysis of Karst Surface Anisotropy Using Directional Semivariograms, Slovenia

The paper presents a study of the anisotropic properties of the karst surface through the use of semivariograms. Karst is formed by hydrogeological and tectonic deformations that determine the surface and subsurface characteristics of the area. Among the most prominent surface features are dolines, which generally form in a linear direction. Semivariograms can be used to determine both the preferred direction of anisotropy and the degree of anisotropy. The surface exhibits the greatest elevation variability in the direction of the most diverse terrain, corresponding to dolines. The results, based on the eight karst areas studied, show that it is possible to detect and, more importantly, quantify anisotropy in all karst areas, although in some cases it is impossible or difficult to detect visually. The directions of the semivariograms agree very well with those obtained from the visual inspection of the maps, as well as with the orientations of the main faults. The method is therefore very useful for quantitative determination of anisotropy and its interpretation could be greatly improved by using the detailed structural geological maps of the karst.