GIS-based morphometric study to genetically characterize dolines in the SE sector of the Classical Karst Region (NE Italy)

Starting from October 2022, in collaboration with ISPRA (Italian Institute for Environmental Protection and Research) and the Geological Survey of the Friuli Venezia Giulia Region, activities have been launched for the creation of the Sheet 110-131 ”Trieste-Caresana” of the Italian Geomorphological Map as part of the CARG project. The territory to be mapped includes a section of the Italian part of the Classical Karst Region, the one limited by the village of Aurisina (NW) and the Rosandra Valley (SE). The Karst area is globally renowned for its pronounced expression of the karst processes and the wide variety of landforms. For these reasons it has represented the cradle of karst studies since the end of the 17th century. In the Classical Karst area, dolines are probably the most distinctive landforms, being widespread and characterized by significant variety in shapes and sizes. One of the main challenges related to characterization of dolines in a mature karst context is the difficulty in determining their genetic process with a defined, large-scale applicable criterion. The dissolution process can, over time, conceal markers that allow to clearly distinguish on the field a doline formed by the collapse of a cavity from one generated by the solution of bedrock. A morphometric approach is proposed to classify dolines in an intensely karstified area on the basis of the predominant genetic process (collapse or solution), using slope steepness as the main parameter. The carrying out of the remote sensing and field surveying activities, as part of CARG project, has facilitated the collection of a substantial amount of new data on epigean landforms. Specifically, a new high-resolution (0.5 meters) Digital Elevation Model has enabled a more accurate delineation of these features for morphometric analyses. All karst depressions and their bottoms were digitized through remote sensing starting from the homogenization of existing data and with the support of field surveys. A total of more than 7,000 dolines have been identified in a total surface area of 115 km2. Information regarding the edges and bottoms of the dolines have been processed using the GIS zonal statistics tool. The areas related to the slopes of the dolines have been extrapolated and then parameterized according to their steepness. This methodology has allowed for the formulation of a preliminary genetic model for dolines in the study area. To validate this model, a sample of dolines with clearly defined genesis has been selected. Geophysical investigations, as well as a borehole, have been planned to verify the GIS-based procedure. The geological context has been also considered, paying particular attention to the dip of the strata.