Geomorphological mapping and anthropogenic signature along the rocky coast in the Tigullio Gulf (Eastern Liguria, Italy)

Abstract

This paper describes the geomorphology of the coastal stretch between Zoagli and Chiavari, a dramatic rocky coast facing the Ligurian Sea which has been severely impacted by anthropogenic morphogenesis, and presents the annexed geomorphological map at the scale of 1:5000. The study area has been historically prone to landslides and is characterized by (i) a geological setting markedly conditioning the geomorphological evolution, (ii) small valley bottoms that have been entirely artificialized, (iii) hillslopes that are almost completely terraced, and (iv) a hydrographic network that is largely modified through channelization and culverting. Unlike many other areas worldwide where agricultural terraces have been abandoned over the past century, here they have partially preserved their agricultural function and have been partially transformed by urban expansion especially in the 1960s and 1970s. The urbanization process has been characterized by the construction of large settlements and discontinuous, scattered buildings associated with the development of residential and tourism infrastructure, which in some cases extends up to, and even beyond, the sea cliff edge. This landscape setting, combined with high relief energy and the ubiquitous presence of infrastructure and facilities, makes the area highly exposed to geo-hydrological hazards, including mass movements, flash floods, and storm surges. The geomorphological map was implemented through collection and review of archival data, geomorphological field surveys and indirect survey techniques based on the photointerpretation of aerial photographs, orthophotos, and satellite images, and the analysis of digital elevation models. All data were imported and managed in a GIS environment allowing an original geomorphological database to be developed. The outcomes of this research provide further insights to enhance both public awareness of geomorphological processes and risk perception, and represent a solid base for supporting local authorities in the sustainable land management and adaption planning.