Anthropogenic impact on river basins: temporal evolution of sediment classes and accumulation rates in the northern Tyrrhenian Sea, Italy

In this study, sedimentological and geochronological data from sections of a core (GRT50) collected in the Northern Latium coastal area were compared to data on pluviometric (rainfall) trends, river flows and the temporal evolution of human interventions in the three most important hydrographic basins (Mignone, Marta and Fiora) of this coastal area. The statistical analysis of pluviometric trends identified variations due to a decreasing trend in the Fiora river basin, whereas in the two other locations the decrease was not so significant. Data from the sedimentological analysis of the core confirmed a progressive decrease in the sandy component, which declined from about 30% to the current level of 7% over the last 36 years. There was no significant variation in the sediment mass accumulation rates (MAR), which were characterized by an almost cyclic trend that was probably determined by the most intense floods in the study area. The results revealed that the variations caused by the fluvial processes have affected the water runoff of the Fiora River, and that the consequent decrease in the sand production has been responsible for the recession of beaches in the coastal area between Tarquinia and Montalto di Castro.