Integrated use of orthophotos and geo-thematic knowledge for sinkhole risk mitigation in Quaternary alluvial plains

Abstract

Sinkholes formation is a widespread reality in Italy, but it is often not as well known as other hazards, such as landslides and earthquakes. The study of these phenomena has led over time to a better understanding of sinkholes and their associated formation mechanisms. In this work, we focused on sinkholes that originate in alluvial contexts, mostly due to deep piping and suffosion phenomena. The objective was to verify the presence of common evidence by observing the sites of 29 sinkholes before and after the collapse phase through the study of historical and recent orthophotos. After producing an initial list of surface evidences common to several sinkholes, various areas in the Italian alluvial plains were examined that maintained the catalogued evidences in the orthophotos. On the basis of these evidences, the number and quality of previous geothematic knowledge and the ease of access, an area in southern Tuscany was selected, where photogrammetric surveys, geophysical surveys and analysis of rainfall data were carried out to verify possible connections with deep piping/suffosion phenomena potentially active in the area and the surface evidences found in the orthophotos.