A Numerical Model of the Wave that Overtopped the Vajont Dam in 1963
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A Numerical Model of the Wave that Overtopped the Vajont Dam in 1963 Silvia Bosa & Marco Petti
Received: 16 December 2011 / Accepted: 25 September 2012 / Published online: 5 October 2012 # Springer Science+Business Media Dordrecht 2012
Abstract The Vajont landslide took place in northern Italy on October 9th 1963 and caused a huge impulse wave to travel along the artificial reservoir and overtop the dam, flooding and devastating a considerable area along the Piave riverbed. In this event about 1900 people died, 1700 of them in the Piave Valley alone. The water depth of the wave in some points exceeded 50 m. Although the phenomenon is clearly tridimensional, the application of a pure 3D hydraulic numerical model to this wide and natural territory is very complicated. Recently, the authors have presented a numerical model of the impulse wave that wasted the Vajont basin as a consequence of the landslide Bosa and Petti (Environ Model Softw 26:406–418, 2011). In this paper, a 2DH numerical model has been applied to study the effects of the overtopping wave in the Piave Valley, in order to verify if the simplifications assumed by a 2DH model still make it possible to describe the evolution of the wave in the proper manner. Keywords Vajont landslide . Longarone . Numerical model . Shallow water equations . Finite volume scheme
1 Introduction On October 9th 1963 at 22:39 a huge landslide of about 270 million m3 slid from Mount Toc into the Vajont artificial reservoir, in north-eastern Italy (Schnitter 1964; Slingerland and Voight 1979; Datei 2003; Genevois and Ghirotti 2005). The amount of water in the basin at that moment was about 115 million m3. The resulting displacement of water caused the generation of an impulse wave that spread throughout the basin. Its impressive wave run-up on the north slope of the lake, in front of Mount Toc, reached and damaged buildings located in Casso about 235 m over the original height of the lake surface (Fig. 1a). The resulting wave rundown crashed into the front of the landslide and partially crossed over the slide bulk, reaching the depressions behind the slide (Fig. 1b). On the east side of the basin, a portion of the water which This paper was originally presented at the EWRA2011 conference Catania June 29th – July 2nd 2011.
S. Bosa (*) : M. Petti Department of Chimica, Fisica e Ambiente, University of Udine, via Cotonificio 114, 33100 Udine, Italy e-mail: [email protected]
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was pushed forward by the landslide formed a wave with smaller amplitude that travelled to the east, reaching the eastern most end of the reservoir in the mountains. During the whole event several impulsive waves crested the dam or moved onto the surrounding slopes which became a way for the water to move out into the narrow canyon that connects the dam to the Piave Valley (Bosa and Petti 2011). The mass of water that poured into the canyon, compressing the air, generated a wave of pressure that acted as a wind. This “wind”, propagating at a speed greater than the waterfront, prec
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