Relating 137Cs and sediment yield from uncultivated catchments: the role of particle size composition of soil and sediment in calculating soil erosion rates at the catchment scale

Abstract Purpose Soil loss is considered one of the most important consequences land degradation as it affects production agricultural and forested areas, natural equilibrium aquatic ecosystems downstream. For these reasons, availability tools techniques able to identify areas at risk essential. Over last 3–4 decades, theoretical models, based on use 137 Cs, an anthropogenic radiotracer, proved be very effective for this purpose. However, models require specific information soil sediment particle size provide estimates erosion or deposition summarised by a correction factor ‘ P ’. Empirical methods calculation assume basic hypothesis that selectivity takes place in processes results general enrichment fine component sediments corresponding higher radionuclide activity. In contribution, we demonstrate not valid everywhere, consequently, cannot estimated using traditional approaches. Materials A long-term experiment, conducted Southern Italy two small experimental catchments (approximately 1.5 ha size), which measurements yield are available period 1978–2020, used work. More specifically, Cs carried out within reference area provided basis obtain rate sites. Combined activity both soils sediments, obtained 46 events, were also explore possible effects final loss. Results discussion Particle analyses showed there evidence eroded finer fractions. Conversely, radiometric revealed generally lower than surface soil. These reflect decreasing associated with depth undisturbed deeper horizon soils. findings preclude application empirical calculate , suggest opportunity use, erosion, = 1. This assumption uncertainty analysis spatial variability value incorporated into Diffusion Migration Model (DMM) rates study catchments. Conclusions The DMM values close during period. overall demonstrated DMM, if properly calibrated value, can useful tool individuate more prone risks appropriate strategies reduce