Geomorphological Evolution and Sedimentology of the Ombrone River Delta, Italy

The geomorphological evolution and nearshore sediments textural characteristics of the Ombrone River delta are here described. The delta evolution, as deduced from archaeological and historical sources as well as from traditional geological studies, has been influenced by changes in land use that occurred during the last 2,500 years within the Ombrone River catchment area. The sedimentological study has been carried out using different granulometric data analysis techniques, such as the comparison of graphic parameters, grain-size spectra map analysis, and cluster analysis. These results are concordant with data coming from numerical modelling of longshore transport energy. The resulting sediment grain-size uniformity is explained on the basis of the recent Ombrone River plain evolution, which prevented coarse sediments from reaching the outlet, and also by wave energy which attacks the beach and removes the fines even at greater depths.