Rockfall source areas assessment in an area of the Pollino National Park (Southern Italy)

Abstract

In the mountainous areas, rockfalls are a common type of massmovements that represents a major cause of fatalities and damages to properties because of their high energy and mobility. For this reason, the assessment of rockfall hazard and risk constitutes an important issue for technicians, administrators and local planners and requires reliable methods, in order to assure a proper land management. This paper is an attempt to assess rockfall susceptibility; in particular, the attention has been focused on the potential rockfall source areas assessment in the territory of the twenty-four Lucanian municipalities belonging to the Pollino National Park (Southern Italy). A DEM-based approach has been used, according to the Slope Angle Distribution (SAD) procedure, allowing to identify the most important Morphological Units of the topography: Cliffs, Steep Slopes, Foot Slopes and Plains. A terrain unit (usually a grid cell) is considered as potential rockfall source when its slope angle lie over an angle threshold, which is defined where the Gaussian distribution of the morphological unit “Cliffs” become dominant over the one of “Steep slopes”. The software Histofit [31] has been a very useful tool for the assessment of rockfall susceptibility. The results of the application of this approach have been compared with the rockfalls niches observed on the field in order to validate the method. Finally, the influence of the cell size of the DEM has been inspected by applying the methodology over two different DEM resolutions (5 m and 20 m).