Comparing long-term observations of sediment yield with estimates of soil erosion rate based on recent 137Cs measurements. Results from an experimental catchment in Southern Italy

Recent increase of soil erosion rates in Southern Italy emphasizes the need to iden-tify areas subjected to higher environmental risks. Over the last few decades, severaltechniques have been used to this purpose. They include mainly experimental sites,like plots and catchments of different size, and the use of prediction models cali-brated using local parameters. More recently, some of the limitations associated withthese techniques suggested the use of radiotracers, mainly137Cs, both as alternativeand complementary tools to traditional methods. However, some of the assumptionsassociated with the application of the137Cs technique still require testing and valida-tion to provide robust estimates of soil erosion rate. These assumptions relate mainlythe137Cs spatial variability on the reference area and the effects of possible addi-tional fallout due to nuclear accidents (e.g., Chernobyl and/or Fukushima). In this con-tribution, a small experimental catchment located in Calabria, Southern Italy, wasselected as a study area by virtue of its long-term record (29 years) of sediment yieldmeasurements. This database made it possible a comparison between long-termobservations and estimates of soil erosion rate provided by recent measurements of137Cs. The overall results indicate that if the uncertainty of the reference value istaken into account and the Chernobyl additional flux is incorporated into a physicallybased conversion model, the latter is able to provide robust estimates of soil erosionrate in the area.