Relative sea-level rise and marine erosion and inundation in the Sele river coastal plain (Southern Italy): scenarios for the next century

In order to assess the effects of possible future sea-level rise in the Sele plain, the lowlands prone to inundation and the rate of coastal erosion in the years 2050 and 2100 have been discussed and some conclusions are here proposed. The sea level at these two dates was calculated as the combination of three components: response of Italian coastal zones to the past deglaciation, variations in ocean volume due to the global warming and vertical land movements. The morpho-stratigraphical data, chronologically supported by C-14 and by archeo-tephro-stratigraphical dating, have allowed the identification of paleo-sea levels of the upper Pleistocene and Holocene (Amato et al. 2011). Such paleo-sea levels compared with those of the tectonically stable areas (Lambeck et al. 2011), permitted the detection of the different vertical land movements in the study area. In particular, in the SE sector of the coastal plain, the Holocene paleo-sea levels are slightly higher (ca. 1-2 m). These values could be considered due to a gentle uplift of the area during Holocene times (0.22 mm/year). In the central sector of the plain, near the Sele river mouth and in the NW sector, between the Sele and Tusciano river mouths, the altitude of the Late Quaternary coastal and lagoonal deposits are slightly lower (ca. 2-3 m). These values could be related to a gentle subsidence of the area during the Holocene (0.4 mm/year). The sea level rise of 5.9 mm/year (IPCC 2007) and 14 mm/year (Rahmstorf 2007) was considered to represent the maximum trends in the ocean volume variation at global scale. The third component, the glacio-hydro-isostasy, was represented by the value of 0.44 mm/year identified by Lambeck et al. (2011) at the Sele plain. The sum of these three components allowed to identify three sea-level scenarios slightly different for the northern and the southern sector of Sele plain, with values ranging from 357 to 1,526 mm and from 307 to 1,424 mm, respectively. For each scenario a simple approach was used, mainly based on the topographic elevation analysis of study area, applied to identify the extension of possible areas of inundation. It corresponds to a minimum value of about 0.42 km(2) for the 2050 AD and a maximum value of 7.6 km(2) for the 2100. Furthermore, according to the methodology proposed by Davidson-Arnott (2005), also the beach erosion was evaluated. The computations showed a potential mean landward retreat of the shoreline ranging from 19 to 93 m.