Abstract

The river Casale basin is placed in the Lucanian Apennine near Viggiano (Potenza). The main stream, Vth class, is left tributary of the river Agri. The basin mostly extends over complex rocks with very low permeability (Galestri, Gorgoglione Flysch, Albidona Flysch), that often are subject to failures. The stream pattern is dendritic elongated, with N-S direction and low elongation ratio (Re = 0,5). The IIIrd, IVth and Vth class stream orientation is strictly controlled by the Plio-Pleistocenic structural features. The river network geomorphic quantitative analysis emphasizes the young stage of drainage organization of the Casale Basin, characterized by uplift related active dynamics. The morfogenesis of the area is thence controlled by neotectonics. The surface and deep failures of the Galestri are linked to a big Pliocenic anticline. The formation, hard fractured, is subject to spread streaming, rapid erosion and translation landslides. The intense Pleistocene regional uplifting caused a quick deepening of the river network and acclivity increase that, together with the lithology features and the slope-plunging attitude of the Gorgoglione Flysch, has encouraged the landslides of the eastern slope of the Casale valley. Here the rototranslation is the most common failure mechanism that has given rise to a morphology characterised by landslides slopes and terraces, trenches and mudflows. At the moment the landslide reactivation is linked to the bank erosion which continuously removes the tip, causing the restoration of active conditions. The latter are facilitated by the low resistance of the slided rocks, with middle-high plasticity and subject to bulging, by the increase of the water pressure and by the high seismicity of the area.

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