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 identify areas subjected to higher environmental risks. Over the last few decades, several techniques have been used to this purpose. They include mainly experimental sites, like plots and catchments of different size, and the use of prediction models calibrated using local parameters. More recently, some of the limitations associated with these techniques suggested the use of radiotracers, mainly 137Cs, both as alternative and complementary tools to traditional methods. However, some of the assumptions associated with the application of the 137Cs technique still require testing and validation to provide robust estimates of soil erosion rate. These assumptions relate mainly the 137Cs spatial variability on the reference area and the effects of possible additional fallout due to nuclear accidents (e.g., Chernobyl and/or Fukushima). In this contribution, a small experimental catchment located in Calabria, Southern Italy, was selected as a study area by virtue of its long-term record (29 years) of sediment yield measurements. This database made it possible a comparison between long-term observations and estimates of soil erosion rate provided by recent measurements of 137Cs. The overall results indicate that if the uncertainty of the reference value is taken into account and the Chernobyl additional flux is incorporated into a physically based conversion model, the latter is able to provide robust estimates of soil erosion rate in the area.