Historical Analysis of Shoreline Dynamics and Evolution at the Mouth of Calabrian Torrents Stabilized with Check Dams

A survey was conducted on the historical evolution of the shoreline at the mouth of eight watersheds in Calabria (south Italy). The investigated watersheds-coast systems fall in the Ionian (six) and the Tyrrhenian side (two) of the Aspromonte Massif (southern Calabrian) and are characterized by significant differences in terms of climatic and geomorphological features. The torrents under study have been stabilized with check dam systems installed from 1954 to today. A comprehensive study was conducted on approximately 700 check dams located across the ‘mountain,’ ‘intermediate,’ and ‘valley’ reaches. The volume of sediments associated with shoreline changes (typically retreat, occasionally advance) and those accumulated upstream of the check dams (generally silt up a few years post-construction) were estimated and calculated. The findings reveal a connection between the tendency of the shoreline to retreat (with retreats observed up to 170 m and affected coastline sections extending up to 5 kms) and the construction of transverse control structures. Overall, the results suggest that particular attention should be paid to the number, location, and type of retention dams in valley reaches, which are responsible for the immobilization of a large part of the sediment from upstream. The valley reaches of these streams, in fact, cross the interface areas between rural and urbanized environments, where hydraulic safety is a priority. However, a more appropriate design of the hydraulic works in these river reaches can make it possible to combine the needs of hydrogeological safety with the stability of the shoreline asset.