Estimation of soil erosion and sediment yield integration with RUSLE and SDR models in the Mesima basin, Calabria, southern Italy

Water-induced soil erosion is a significant contributor to land degradation, posing a threat to both environmental and socioeconomic sustainability. The present study aimed to evaluate the mean annual soil loss in the Mesima river basin (area: 806.41 km²) located in the middle-southern sector of the Calabria region, southern Italy. Additionally, the study calculated the mean sediment yield and identified the primary sediment sources within the basin. A spatially distributed approach was employed, integrating the Revised Universal Soil Loss Equation (RUSLE) and Sediment Delivery Ratio (SDR) models with Geographic Information Systems (GIS) and remote sensing techniques. The results showed that annual soil loss within the basin varied from 0 to 258.35 t/ha/yr with a mean of 3.37 t/ha/yr. The computed yearly soil loss was approximately 271.76 × 10^3 tonnes. Additionally, the estimated sediment yield within the basin ranges from 0 to 95.75 t/ha/yr, with a mean of 1.07 t/ha/yr; consequently, the yearly sediment yield will realistically amount to 86.64 × 10^3 tonnes. These results indicate that approximately 31.9% of eroded soil is transferred to streams, while 68.1% remains and is deposited without reaching the streams. Our results show that the Mesima basin is highly diverse in terms of erosion and sediment yield, owing to the variable topographic, geomorphic, and land-use/cover characteristics of its sub-basins. Topographic steepness (LS factor) contributes the most to soil erosion, followed by crop and management (CP) factors in most sub-basins. The current investigation effectively identified erosion-prone areas and critical sediment sources, offering valuable support for sustainable land management and soil conservation planning.