Morphometric properties of dolines in Matarsko podolje, SW Slovenia

Matarsko podolje, in SW Slovenia, is a karstic surface with many dolines, which appear between the flysch-composed Brkini hills in the NE and Mt. Slavnik in the SW. We have analyzed dolines to find the morphometric parameters of the depth, area, volume, and circularity index and also calculated the doline density and pitting index. All parameters were also calculated separately for individual lithological units to explain the variations of the calculated values among these groups. Morphometry was performed in GIS environment on a 1 × 1 m digital elevation model with bare earth obtained by lidar. The results show a high density of dolines (94 dolines/km²) and also a high pitting index (R_p = 8.27) compared to other studies. There are some significant differences between the measured values in individual lithologies, as the depths, areas, and volumes are largest in dolomitic beds (other beds include various types of limestones and carbonate breccia). The median values of depth, area, and volume are 2.98 m, 541 m², and 690 m³. The circularity index is also lowest in dolomite beds and Kozina limestones; however, the differences are not so pronounced as for areas and volumes. Dolines' longer axes are parallel to the directions of major structural elements; however, more detailed mapping should be done to confirm the influence of faults and fracture zones on the doline geometry.