Identifying Sediment Source Areas in an Agricultural Mediterranean Basin

Human activities have significantly escalated soil erosion rates across landscapes. The impact of accelerated soil erosion and its socio-environmental consequences have been a focal point of scientific inquiry for over a century. Effective basin management plays a critical role in mitigating soil depletion and protecting soil and water resources, necessitating the quantification of erosion and identification of sediment sources within basins. The aims of this work were to (i) evaluate SWAT model suitability in simulating streamflow and soil erosion in the Canale d'Aiedda River (Italy), (ii) Evaluate the effectiveness of the model in identifying critical sources areas to guide erosion control. Following sensitivity analysis, the model underwent calibration for runoff and sediment dynamics. At the basin scale, average water yield was calculated at 147.9 mm, equivalent to 25% of total annual rainfall (612.8 mm), with an estimated annual sediment load of 0.035 t ha-1year-1. Subbasin analysis revealed changes in sediment yield, showing significant variation among upper (0.9 to 4.1 t ha-1year-1), lower, and central (< 1 t ha-1year-1) parts of the basin area. Contrarily, sediment deposition in the river reaches was most pronounced in the central basin areas, characterized by an alluvial plain. Major sediment contributors were identified as winter wheat and olive land uses. These findings underscore the vulnerability of Mediterranean basins as fragile ecosystems requiring effective soil conservation measures.