Multi-approach study to genetically characterize dolines in the SE sector of the Classical Karst Region (NE Italy)

Since 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 underway for the development of Sheet 110-131 “Trieste-Caresana” of the Italian Geomorphological Map, within the framework of the CARG project. The area under investigation covers the Italian sector of the Classical Karst, bounded by the village of Aurisina to the northwest and the Rosandra Valley to the southeast. This region is internationally recognized for the intensity of karst processes and the richness of related landforms, and has served as a reference area for karst studies since the late 17th century. The final cartographic products of the CARG project reveal a very high density of karst landforms, as evidenced, for example, by the presence - within an area of 115 km² - of 10 km² of karren fields and “griza”, more than 2,700 cave entrances and over 7,000 dolines. Within the Classical Karst, dolines are among the most emblematic and widespread landforms, exhibiting a remarkable range of morphologies and dimensions. A key issue in their characterization - particularly in mature karst systems - is the difficulty of defining their genetic origin based on field evidence alone. Over time, dissolution processes may obscure diagnostic features that distinguish dolines formed by collapse from those resulting from solution. To address this, a range of morphometric parameters is assessed to classify dolines according to the prevailing genetic mechanism. Remote sensing and field survey activities conducted as part of the CARG project have enabled the acquisition of extensive new data on surface karst landforms. In particular, the availability of a high-resolution (0.5 m) Digital Elevation Model has significantly improved the accuracy of morphometric analyses. All karst depressions and their bottoms were digitized. A morphometric analysis within a GIS environment was carried out to extract significant parameters and assess their applicability in determining the genetic process of individual dolines. In order to calibrate the selection of morphometric parameters to be used, several in-depth study methodologies were applied at selected specific sites. In particular, geophysical surveys were conducted to analyze the configuration of the bedrock beneath the soil cover. ERT profiles, refraction seismics, and electromagnetic methods were employed. At the same time, a geomorphological analysis was carried out in the study area to highlight the relationship between the presence of dolines and ipogean karst features, whether active or relict. This methodology made it possible to develop and propose a preliminary genetic model of dolines for the Classical Karst, accompanied by considerations regarding the most effective strategies for representing these landforms in geomorphological mapping.