Shoreline change and coastal erosion: The role of check dams. First indications from a case study in Calabria, southern Italy

Currently, most of the world’s coastal territories are subject to erosive processes, often caused by an alteration of sediment balance due to both natural and anthropogenic factors. This issue is relevant in many Mediterranean territories such as Calabria region, in southern Italy. Here, considerable anthropogenic pressures affect about 750 km of coast on which debouch short torrential rivers locally termed ‘fiumare’. The regional climate, hydrology and geomorphology leads to intensive fiumare catchment erosion and high fluvial solid loads. The work focuses on the Gallico fiumara, chosen as case study affected by an intense hydraulic regulation programme in order to investigate the poorly studied effects of engineering control works on shoreline changes. The paper has considered the effects of the 264 check dams (completely filled a few years after their realization) only investigating the relationships between the volume retained by the structures and shoreline change during the several arrangement campaigns. Although the work does not consider the other processes that explain the complexity of the watershed-coast sediment balance, it has been clearly demonstrated an influence of check dam system on the evolution of the shoreline, especially due to the hydraulic works installed in the lower part of the watershed. In the light of the results obtained, it would be desirable to promote a debate on the opportunity to convert or demolish the check dams in the torrent reaches closest to the coast, where, moreover, the engineering control most reduced the already limited natural riverbed slope.