Long-term evolution of the shoreline of the south Lazio region (Italy) littoral cell by combining historical aerial photography and satellite imagery

Historical maps, aerial photos, and satellite images are often used to investigate coastal area conditions and their historical evolution, in terms of shoreline location, coastal structures deployment, and anthropic pressure. The application of multi-temporal shoreline extraction by combining historical aerial photographs and tri-stereo Pleiades images of the littoral cell bounded by Capo d’Anzio and Circeo headlands (Central Italy, Lazio region, Tyrrhenian Sea) is illustrated and discussed in this paper. The analyzed coastal area presents great environmental and tourism values, mainly due to the presence of the Circeo National Park, and its Special Protection Areas (SPAs) and Sites of Community Interest (SCI), belonging to the Natura 2000 network. The area is also characterized by its own high morphological vulnerability due to the absence of sediment supplies and the presence of coastal structures in the updrift area that trap, at least partially, the incoming longshore sediment transport. The available aerial photographs and satellite images have been orthorectified by using aero-triangulation and rational function techniques, respectively. The digitized shorelines, spanning from 1954 to 2019, have been used to gain insight into the advancing/retreating coastal stretches along the area, by applying the Transect Based Analysis and the Area Based Analysis. The obtained results have been related to the Lazio region coastal management measures, implemented within the same time frame.