Comparison of National and Regional Assessments of Soil Loss Rates by Water Erosion and Soil Erosion Control: An Application to the Tuscany Region (Italy)

Soil erosion assessments for policy are often derived from continental-scale datasets, but their suitability for regional planning remains unclear. This study compares two Revised Universal Soil Loss Equation (RUSLE) applications for Tuscany, Italy: one using high-resolution regional data (TuscReg) and another using European-scale data from the European Soil Data Centre (TuscNat). We found the mean estimated actual soil erosion rate was 58% higher in the regional assessment (10.7 vs. 6.8 Mg ha−1 yr−1). Remarkably, the spatial patterns diverged significantly in the complex landscapes characterizing some Tuscan soil regions. In mountainous areas like the Apuan Alps, TuscReg estimated soil erosion control (potential minus actual erosion) to be over 500 Mg ha−1 yr−1 greater than TuscNat for 30% of the area. Correlation analysis revealed these major differences were primarily driven by disparities in the rainfall erosivity (R) and soil erodibility (K) factors. Our results demonstrate that while EU-scale models provide a consistent, broad-scale overview, they can substantially underestimate erosion and the ecosystem service of erosion control in specific, high-risk environments. To implement policies like the EU Soil Monitoring Law (Directive (EU) 2025/2360), regional-scale data are essential to accurately identify priority areas for soil conservation and set meaningful local thresholds.