Investigating sediment sources within a small catchment in southern Italy

Soil erosion is a serious problem in many areas of Italy, particulary in the south, where rates of soil loss can exceed 100-150 t ha(-1) year(-1). Although the impact of these high rates of soil loss has traditionally been assessed in terms of soil degradation, off-site problems related to more general environmental degradation are attracting increasing attention. In order to implement meaningful sediment control strategies, it is necessary to establish both the nature and the location of the main sediment sources within a catchment. Sediment fingerprinting has been increasingly identified as an effective approach for assembling information on suspended sediment sources. The study reported uses source fingerprinting techniques, based primarily on radiometric fingerprints (Cs-137 and unsupported Pb-210) to establish the primary sediment sources within a small forested catchment (1.38 ha) located in Calabria, southern Italy, where independent information on the spatial pattern of surface erosion rates was available from 137Cs measurements. The source tracing investigation showed that most sediment originates from the south-facing slopes, where the tree cover is discontinuous, emphasizing the importance of vegetation cover in influencing sediment mobilization from the study area. These findings are consistent with the previous work involving Cs-137 measurements, which again identified the south-facing slopes with discontinuous tree cover as the areas with the highest rates of soil loss.