Evolution of the North Tyrrhenian Calabrian beaches in the last 50 years

Abstract

Coastal erosion and degradation is of paramount importance for a peninsular region like Calabria, which has only 6% of plains (concentrated along its coast) and whose economy depends largely on sea-side tourism. This paper is aimed to reconstruct and interpret the very recent (1953÷83 and 1983÷99) coastline evolution of a 80 km reach of the Tyrrhenian coast of Calabria. Data regarding beach progradation and retreat were obtained by comparing aerial photos and topographic maps of different epochs, coupled with direct measurements of the present (1999) beach width at numerous control points. The lithological nature of beach deposits sampled in twenty sites was also used to delineate the geomorphological domains feeding the various coastal sectors. In order to evaluate the role of human impact on the fluvial supply of sediments to the beaches, the major streams of the study area were classified by different degrees of artificial canalization. By analysing the obtained data in terms of time-space distribution of progradation and erosion events, it was possible to make some interesting deductions about the general evolutionary trend of the last 50 years and the possible causes of the observed changes. The beaches of the considered coastal reach experienced an average rate of retreat of about 0,9÷1 m/year in the period 1953÷1983. Such tendency was then gradually reduced during the period 1983÷1999, until a situation of substantial balance was reached. Most probably, this result was only due to the progressive expansion of artificial defences, which affect nowadays about 50% of the available beaches. A decisive role of anthropogenic factors can be recognised also for the erosion phenomena observed in the period 1953 to 1983, which reversed the pre-existing tendency to progradation. The present coastal dynamics shows a coexistence of prevailing erosion on emerged beaches and availability of long-shore moving sediments, which encourages the search for new measures of defence and reconstruction of beaches that could create less impact than the ones till now adopted.