Assessment of Erosion in River Basins: A Distributed Model to Estimate the Sediment Production over Watersheds by a 3-Dimensional LS Factor in RUSLE Model

Erosive processes influence on several phenomena. In particular, they could influence on land depletion, on vegetation weakening, on aggradation phenomena of intermediate, and plain reaches of rivers, on waterways interruption due to overaggradation phenomena caused by floods, and on the losses of water volumes that may be stored in reservoirs. Among the models proposed in the literature for the prediction of erosion on the annual scale, one of the most widely used is the Revised Universal Soil Loss Equation (RUSLE). In the present paper, starting from the definition of the original model, the authors improved the important combined slope length and slope angle (LS-factor), taking into account the mutual interaction of solid particles, in terms of path and confluences, so as to transform the model, which was first classified on a slope scale or at most on a parcel one, into a distributed model on a basin scale. The use of a distributed approach is an integral part of the analysis of the hydrogeological risk. In this way, it is possible to obtain a map of the erodibility of any basin, from which to derive the most vulnerable areas. The proposed methodology has been tested on the Camastra Basin, located in Basilicata Region of Southern Italy