Tommaso Moramarco, Silvia Barbetta, Claudia Pandolfo, Angelica Tarpanelli, Nicola Berni, Renato Morbidelli, 2014, The spillway collapse of the Montedoglio dam on the Tiber River (central Italy): data collection and event analysis, Journal of hydrologic engineering (Online) 19 (2014): 1264–1270. doi_10.1061/(ASCE)HE.1943-5584.0000890,
URL: http://www.cnr.it/prodotto/i/271041

A large number of dams were built in Italy in the first decades of the last century to supply the need of industrial, electric power, agricultural and drinking purposes. Among them, the Montedoglio dam, an important reservoir on the Tiber River located in central Italy, with a drainage area of 276 km2 and a maximum storage volume of about 153 Mm3. The dam is an earth-fill structure with overfall spillway partly controlled by two sluice gates. On 29th December, 2010 due to the partial sudden collapse of the spillway a huge water volume flooded the valley below the dam with high damage for the territory and population, luckily without causalities. Considering that scarce data are available for this type of events worldwide, this paper aims, on the one hand, to illustrate the collected data of the event in terms of reservoir levels, discharge hydrograph observed at downstream gauged river sites and flooded valley area, on the other hand, to simulate the breach evolution and the downstream propagation of the outflow. Considering the Nash-Sutcliffe performance measure in simulation of the recorded reservoir levels, the time of breach formation and the corresponding discharge coefficient are obtained through an optimization procedure and values of 0.02 h and 0.15 are found, respectively. Finally, the Manning's roughness coefficients for the downstream main channel and the floodplain areas are detected through a methodology based on one-dimensional hydraulic modelling by considering different flooding scenarios of valley.

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