Soil loss assessment in the Turbolo catchment (Calabria, Italy)

Soil loss caused by accelerated erosion is a growing problem in the Mediterranean belt in general, and in many parts of the Calabrian region (Southern Italy), in particular. It is due to the combination of peculiar geo-morphological, pedological and climatic features, very often exacerbated by unsuitable land management. The aim of this study was to analyze and map soil loss by water-induced soil erosion at catchment scale. Soil loss was quantified using the revised universal soil loss equation (RUSLE) model implemented in a geographical information system (GIS). The RUSLE is an empirical model which estimates the average annual soil loss that would generally result from splash, sheet and rill erosion. Soil loss (A) is measured as a product of rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), land use (C), and support practice and management (P). The analysis showed that the total soil loss estimated in the study area was 8,949.7 t yr-1 with an average annual soil loss of 3.07 t ha-1 yr-1. Spatial variation and rates of soil erosion are mainly linked to land use, and the rate of soil erosion varied from less than 1 t ha-1 yr-1 in the wooded areas to more than 10 t ha-1 yr-1 in the barren lands. In addition, the comparison between soil loss and slope maps showed that more than 50% of the estimated soil loss involved slopes with a gradient of over 20°. Finally, the soil loss map was classified into five classes: very low, low, moderate, high, and very high. About 17.5% of the study area falls in the high to very high soil loss classes, while about 53% of the study area falls in the very low soil loss class.