Soil erosion susceptibility maps of the Janare Torrent Basin (Southern Italy)

Soil erosion susceptibility mapping provides a classification of the land surface into zones each of which has a different likelihood, or risk, of experiencing specific soil erosion processes. Such maps are fundamental to land-use planning aimed at the conservation of soil resources. In this paper, 1:46,500-scale maps showing susceptibility to different soil erosion processes (sheet/rill erosion, gully erosion and landslide-induced mass erosion) are presented. The study was carried out in the 10.5 km2-wide Janare Torrent basin, located in Southern Italy. The basin was first characterized from a lithological, morphological and land-use standpoint. Landslides, gullies and landsurfaces affected by intense sheet and/or rill erosion were then surveyed and mapped by integrating the analysis of aerial photos and topographic maps with field observations. Using ArcView GIS 3.2 software, the densities of each type of erosional landforms in each lithological, slope, aspect and land-use class were obtained by means of intersections procedures. From densities, weights expressing the susceptibility to soil erosion of each class were calculated using bivariate statistical analysis. The thematic maps were then reclassified according to the calculated weights and overlain in a GIS environment, thus calculating the soil erosion susceptibility value in each point of the study area. The range of susceptibility values was finally subdivided into four classes to produce the final susceptibility maps. The procedure is based on processing of directly surveyed, mapped and interpreted data, is easy to apply, allows frequent updating of the susceptibility assessment, and is scientifically reliable.