Investigating sediment sources within a small catchment in southern Italy.

Soi! erosion is a serious problem in many areas of Italy, particularlr in the south, where rates of soil loss can exceed 100-150 t ha-I year' . Although the impact of these high rates of soi! loss has traditionally been assessed in terms of soil degradation, off-site problems related to more generaI environmental degradation are attracting increasing attention. In order to implement meaningfu1 sediment control strategies, it is necessary to establish both the nature and the location of the main sediment sources within a catchment. Sediment fmgerprinting has been increasingly identified as an effective approach for assembling infonnation on suspended sediment sources. The study reported uses source fingerprinting techniques, based primarily on radiometric fmgerprints (137Cs and unsupported 21Opb) to establish the primary sediment sources within a small forested catchment (1.38 ha) 10cated in Calabria, southem Italy, where independent information on the spatial pattem of surface erosion rates was available from 137Cs measurements. The source tracing investigation showed that most sediment originates from the southfacing 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 137Cs measurements, which again identified the south-facing slopes with discontinuous tree cover as the areas with the highest rates of soil loss.