Integrating 10Be analyses and an empirical erosion model to unveil catchment-scale landscape and sediment dynamics

In recent decades, the quantification of Earth surface processes such as erosion, sediment transport, and deposition has gained increasing attention, with a focus on investigating their interplay across different spatial and temporal scales. This study contributes to address these challenges by combining in-situ cosmogenic ¹⁰Be isotopic analyses with a modified version of the Erosion Potential Model (EPM) to explore landscape and sediment dynamics in the Sfalassà stream catchment in Calabria, southern Italy.

A total of 26 samples, including river sands of two different grain sizes and rock samples, were collected to estimate long-term erosion rates, sediment residence times (average exposure ages), and rates of vertical river dissection across the catchment. The adoption of ¹⁰Be cosmogenic nuclide enables a detailed understanding of erosion and sediment transport processes on millennial timescales, providing time frames for the main processes that have shaped the basin. The Sfalassà catchment, characterized by a diverse range of lithologies, geomorphological units, vegetation cover, land uses, and anthropogenic activities, was selected as a representative pilot basin in the central Mediterranean area. Sampling was conducted across the main channel and its tributaries to ensure comprehensive coverage. Field surveys formed the core of our sampling strategy, supplemented by aerial photo interpretation, GIS and thematic mapping analyses to enhance site selection.

The EPM was upgraded using the catchment’s geological and pedological erodibility parameters. The specific weights of geological parameters and the differentiation of lithological classes assigned to various lithologies available in the literature were modified, trying to enhance the model accuracy for estimating medium-term erosion rates. This adjustment involved an integration of the spatial distribution of rock outcrops with that of major soil types, focusing on their varying susceptibility to surface erosion. Additionally, rainfall data were extrapolated at different elevations using a regression function of data from weather stations. In contrast to the EPM, the ¹⁰Be analyses provided precise and direct in situ measurements, enriching our understanding of catchment-scale erosion processes through the integration of methodologies.

Despite operating on different temporal scales, the integration of isotopic data with the EPM may enhance the model’s accuracy. This synergy may provide a more robust framework for the quantification of sediment fluxes and erosion process modeling, contributing to a deeper understanding of sediment dynamics. This interdisciplinary approach not only sheds light on the connectivity between sediment source areas and the drainage system but can also suggest practical tools for assessing and managing sediment dynamics and coastal erosion risks. Based on the rates at which river sediments feed coastal areas, it highlights conditions of balance/unbalance in the sedimentary input, thus emphasizing broader geomorphological implications.

The research is part of the "TECH4YOU – Technologies for climate change adaptation and quality of life improvement" project, funded by Next Generation EU (PNRR M4.C2.1.5). By combining geochronological techniques with numerical modeling, this study contributes to advancing methodologies for basin-scale investigations, offering replicable protocols applicable to diverse geo-environmental contexts and improving our understanding of sedimentary processes from source to sink.