Late Quaternary soil erosion and landscape development in the Apennine region (central Italy)

Abstract

This study on past soil erosion processes focuses on a catchment located in a mountainous sector of the Central Apennines, 60 km northeast of Rome. Humans are known to have interacted with the landscape in this region at least since the early Iron Age. The area is highly sensitive to climatic changes and human intervention and thus is susceptible to soil erosion. The environmental impact of past human activities has been examined by geomorphological and sedimentological investigations and supported by modelling operations.Percussion drillings in the floodplains reveal up to 10 m thick alluvial deposits. Combined sedimentological and geomorphological analysis suggests that the total sediment volume of the valley infill totals about 300,000 m3 of sediments. Radiocarbon dating documents that this alluvial sedimentation started during the sub-Atlantic period (between the 1st and 2nd centuries BC) and coincides with a shift from a flood-quiescent to a flood-prone phase. According to historical sources, the flood phase correlates chronologically with the Roman occupation of the area, when they practiced extensive logging in their territories. GIS modelling operations show a loss of soil surface of about 71 cm on average for the entire catchment (1,600,000 m3 loss of soil), if long-term land exploitation for wood supply is assumed. The modeling showed that approximately 80% of the eroded soil has been fluvially transported out of the catchment, so the present alluvial plains may represent only about 20% of the overall lost soil mass.