Predicting Soil Erosion With RUSLE in Mediterranean

Accurate assessment of soil loss is essential for sustainable agricultural production, 11 management and conservation planning, especially in productive rain-fed agro-ecosystems 12 and protected areas. The European Union considers soil as a non-renewable resource and 13 identifies that soil degradation has strong impacts on soil and water resources. In this work the 14 Revised Universal Soil Loss Equation model was applied within a geographic information 15 system in the Estaña catchment (Spanish Pre-Pyrenees) as representative of a Mediterranean 16 agro-ecosystem to elaborate a map of soil erosion at high spatial resolution (5 x 5 m of cell 17 size). The soil erodibility factor (K) is calculated from three different approaches to evaluate 18 the importance of spatial variations in soil texture, field infiltration measurements (K fs) and 19 amount of coarse fragments. The average value of estimated soil loss for the whole study area 20 is 2.3 Mg ha-1 yr-1 and the highest rates are estimated in crops in steep areas (5.8 Mg ha-1 yr-1) 21 and trails (18.7 Mg ha-1 yr-1). Cultivated soils with high soil erosion rates (higher than 8 Mg 22 ha-1 yr-1) represent 20% of the cultivated area. The average value of soil loss in areas with 23 human disturbances (4.21 Mg ha-1 yr-1) is 4.4 times higher than that estimated for areas with 24 natural vegetation (0.96 Mg ha-1 yr-1). Field validation with 137 Cs shows that the estimated 25 value of soil loss in barley fields with the K-K fs-rocks factor improves the model predictions 26 in comparison with those obtained with the K-texture and K-K fs factors. The RUSLE model 27 predicts a decrease in soil erosion in fields in accordance with the increase of the age of 28 abandonment. Predicted values of soil erosion and measured soil organic matter and stoniness 29 in old abandoned fields agree with those in areas of natural forest and indicate the recovery of 30 the original conditions of the soil. Statistical analysis highlights that the C factor contributes 31 most of the variability of the values of predicted soil erosion, the K and LS factors contribute 32 in a similar way and the P factor contributes least to the variability of soil erosion. Cultivated 33 soils developed over clay materials in high slope areas are the most susceptible to soil 34 Soil Erosion in Mediterranean Agricultural Systems 2 degradation processes in comparison with soils developed over …