Quantitative Characterization of Coastal Cliff Retreat and Landslide Processes at Portonovo–Trave Cliffs (Conero, Ancona, Italy) Using Multi-Source Remote Sensing Data

The integration of multiple data sources, including satellite imagery, aerial photography,and ground-based measurements, represents an important development in the study of landslideprocesses. The combination of different data sources can be very important in improving ourunderstanding of geological phenomena, especially in cases of inaccessible areas. In this context,the study of coastal areas represents a real challenge for the research community, both for theinaccessibility of coastal slopes and for the numerous drivers that can control coastal processes(subaerial, marine, or endogenic). In this work, we present a case study of the Conero Regional Park(Northern Adriatic Sea, Ancona, Italy) cliff-top retreat, characterized by Neogenic soft rocks (flysch,molasse). In particular, the study is focused in the area between the beach of Portonovo and Trave(south of Ancona), which has been studied using aerial orthophoto acquired between 1978 and 2021,Unmanned Aerial Vehicle (UAV) photographs (and extracted photogrammetric model) surveyed inSeptember 2021 and 2012 LiDAR data. Aerial orthophotos were analyzed through the United StatesGeological Survey’s (USGS) tool Digital Shoreline Analysis System (DSAS) to identify and estimatethe top-cliff erosion. The results were supported by the analysis of wave data and rainfall from thecorrespondent period. It has been found that for the northernmost sector (Trave), in the examinedperiod of 40 years, an erosion up to 40 m occurred. Furthermore, a Digital Elevation Model (DEM)of Difference (DoD) between a 2012 Digital Terrain Model (DTM) and a UAV Digital Surface Model(DSM) was implemented to corroborate the DSAS results, revealing a good agreement between theretreat areas, identified by DSAS, and the section of coast characterized by a high value of DoD.