L’EVOLUZIONE RECENTE DELLA COSTA MOLISANA (ITALIA MERIDIONALE)

Abstract

Aucelli et al., The recent evolution of Molise coast (Southern Italy). (IT ISSN 0394 – 3356, 2004).
This study deals with the recent geomorphological evolution of the sector of the Adriatic coast referring to the Molise region. The analysis was based on the examination of topographic sheets and aerial photographs referring to the period 1869-1998 and on field surveys to verify and integrate geomorphological data, and to analyse present trends and coastal dynamics. Taking into account morphological and related hydrological features, the coast was subdivided into three sectors (from north to south sectors A, B and C). The collected data were analysed and compared by using a GIS (software Arc View) to obtain quantitative results about the changes of the shoreline and the beach surface which affected the three distinguished sectors during different periods (1869-1907, 1907-1954, 1954-1992 and 1992-1998). For the first period, with reference to data obtained for the sector including the Biferno river mouth (sector C), a substantial stability of the delta and positive beach variations can be evidenced. Within the second period, an inversion of tendency occurred and the erosion of the main fluvial deltas (the Trigno delta in sector A and the Biferno delta in sector C) started. The river mouths erosion was accompanied by the progradation of the adjacent coast sectors giving rise to a general positive beach surface variation. During the following periods (1954-1992 and 1992-1998), the shoreline retreat largely persisted affecting sectors A and C, while sector B was characterised by a slight progradation. On the basis of discussed data, two main evolutive phases can be reconstructed. The first one is characterised by prevailing progradation which lasted at least to 1907 and is evidenced in the study area by the construction of the Trigno and Biferno delta’s. The second phase is controlled by progressive beach erosion, at present still active. The phase of prevailing progradation can be related most probably to the last cold fluctuations of the Little Ice Age, although man induced changes of land-use may have played an important role by favouring soil erosion and sediment production. Conversely, the following phase of erosion can be mostly related to the progressive amelioration of climatic conditions after the Little Ice Age and to the relative hydrological changes, combined with land-use changes essentially related to land-abandonment and, in the last decades, to the interventions on the fluvial systems as gravel mining, channel management and daming.