Assessing the susceptibility to water-induced soil erosion using a geomorphological, bivariate statistics-based approach

摘要

The aim of this study was the assessment, at basin scale, of the susceptibility to water-induced soil erosion processes (i.e. gully erosion and sheet/rill erosion) using geomorphological analysis, Geographical Information Systems (GIS) and bivariate statistics. The study was carried out in a watershed located in Southern Italy. A detailed analysis of the pre-existing literature led to select lithology, land-use, slope angle and slope aspect as soil-erosion determining factors (DFs), as they are "non-redundant" and affect both the soil-forming processes that control soil erodibility and the erosive power of running waters. Water-produced erosional land-forms, such as gullies and areas severely affected by sheet/rill erosion, were surveyed and mapped using classical techniques of geomorphological analysis. The GIS processing of the geomorphological data allowed calculating the areal density of these landforms in each DF class. Weighting values (W,), corresponding to the susceptibility level of each DF class, were calculated using bivariate statistics. Finally, GIS overlay procedures of the thematic maps, previously reclassified on the basis of the calculated W_i allowed to produce two Susceptibility Maps (i.e. Gully Erosion and Sheet and/or Rill Erosion Susceptibility Map). The soil-geomorphological coherence of the produced results has been checked and widely discussed in the framework of the pre-existing literature. Both the geomorphological coherence of the calculated W_i, and the results of the validation procedure suggested a good reliability of the method, which is also relatively easy to apply and update.