Author(s)

G. Lollino, M. Cuccureddu, A. Berra & G. De Renzo

Abstract

A numerical model simulation of an instability phenomenon: the Gardiola case (Germanasca Valley -Italy) G. Lollino1, M. Cuccureddu1, A. Berra1 & G. De Renzo2 1 National Research Council - IRPI di Torino, - Torino Italy 2 Provincia di Torino- Sewizio Difesa del Suolo - Torino Italy Abstract A water course obstruction caused by a landslide is a phenomenon that may cause high risky situations for anthropic sites located both up and down the natural dam. Following the intense raining period of last 13-16 October 2000 in the North West Piedmont and Aosta Valley, a lot of instability cases were reported to the authorities of all Turin Province; in particular, the CNR-IRPI of Turin has been in charge to check the cracks phenomenon that destroyed part of the road that connect Pinerolo to the Germanasca Valley (West Piedmont) with particular regard to the landslide interference with the Germanasca stream. Immediately after the first report, a topographic monitoring system was installed in the area and the relationship between the landslide and the raining phenomena was clear. A numerical model of the system was then developed to assume possible scenarios caused by an eventual collapse of the natural dam, assess the risk of stability and to design appropriate defensive handmade. 1 Introduction The area where the landslide reactivated, is on the left side of the Middle Germanasca Valley, North West of Gardiola, Salza di Pinerolo municipality. In the Gardiola area the valley is very steep and narrow, with a valley floor 30m wide. On the right side, the valley's original glacial profile is deformed with a pronounced gravitational spur. The surface reactivated by the landslide occupies a morphologically well defined hollow along the slope, characterized by scarps and counterslopes features which witness repeated reactivations. Geomorphological evidences of

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