engleski

Simulation of flooding and drying in meteotsunami modelling

Meteotsunamis, sea level oscillations of meteorological origin with periods similar to those of tsunamis, can, in extreme cases, reach significant wave heights and cause large damage to property and even a loss of life. In this study we have taken four historic meteotsunamis in the Adriatic, the largest of which had a wave height of 6 meters, and attempted to improve upon previous numerical simulations (or to compute them for the first time) in order to model the events as accurately as possible. First, a set of simulations was done using a minimum depth of 4 m. Results for Vela Luka (21 June 1978), Široka (22 August 2007) and Mali Lošinj (15 August 2008) showed significant sea level oscillations in the bays but the amplitudes were, at best, 50% of the observed ones. In the case of Stari Grad (19 February 2010) the modelled oscillations were smaller, up to 30% of the observed ones. The situation in Stari Grad was specific that day – sea level was already elevated due to a storm surge and it is assumed that without the storm surge the meteotsunami that hit the bay would not have caused flooding on its own. The next set of simulations included flooding and drying of grid nodes. Grid resolution was enhanced in the entire Adriatic but especially in the four bays where the spatial resolution was several tens of meters and topography was included in order to allow for wave runup. All modelled wave heights were larger than in previous simulations, by up to a 100%. Even though some of the modelled wave heights were still lower than the observed ones, this result is a clear indication that modelling extreme wave heights of destructive meteotsunamis can benefit from a flooding and drying methodology incorporated into the model.

wave, grid resolution, Adriatic, meteotsunami

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