Human Impact on Shoreline Evolution Along the Follonica Gulf (Southern Tuscany): How Tourism May Kill the Goose that Lays the Golden Eggs

Abstract

CIPRIANI, L.E., FERRI, S., LAMI, G and PRANZINI, E., 2011. Human Impact on Shoreline Evolution Along the Follonica Gulf (Southern Tuscany): How Tourism May Kill the Goose That Lays the Golden Eggs. In: Micallef, A. (ed.), MCRR3-2010 Conference Proceedings, Journal of Coastal Research, Special Issue, No. 61, pp. 290–294. Grosseto, Tuscany, Italy, ISSN 0749-0208.Follonica Gulf beach is subject to widespread low-rate erosion, which started in the 19th Century due to river diversion for coastal marsh reclamation. Once rivers were re-directed to the coast; land subsidence induced by water extraction sustained erosion. From 1954 to 1984 mean shoreline retreat was approximately 9 m.In the 1960's, development of coastal tourism villages increased beach use and the need for house protection from storms. Detached breakwaters were built, trapping sand from adjacent coastal sectors. This induced shoreline progradation in protected sectors creating a wider beach, but unprotected coastal sectors experienced severe erosion. Stakeholders requested additional protection: the most developed area was gradually protected by detached breakwaters up to complete closure. Comparing the 2005 and 1954 shoreline positions, we see that out of the total length of approximately 21 km of coastline 8 km are accreting; less than 1 km is stable and over 12 km are eroding. Recently, a marina was built on the eastern margin of the study area; however wave diffraction at breakwater tip induced longshore transport and entrance siltation at the cost of western neighbouring beaches.Tourism industry stakeholders, whose economy is based on beach width and quality, were responsible for such coastal degradation, but now cooperate with local and regional administrations, accepting reduction in the use of hard defences - although shoreline realignment will end up penalising someone. Some detached breakwaters have been lowered to 50 cm below mean sea level, whereas others will undergo similar reshaping in the near future. The two oldest sets of coastal defence are now under study, in order to find solutions for a gradual return to more natural conditions. Changes to the marina configuration are being designed to prevent siltation, reaching a new equilibrium for the adjacent beach. We now realise that money spent for shore protection in some sectors would have maintained the 1950's shoreline position along the whole Gulf using beach nourishment, with no landscape deterioration.