Flooding scenarios due to levee breaking

摘要

In this paper the results of mathematical modelling of flooding scenarios for two important italian rivers are shown. The first concern the middle portion of the Po river, the main italian one. In this region in the nineteenth century occurred some levee breaks that caused the inundation of wide plain regions (500-600 km~2), with considerable water depths. The present embankments characteristics and the river morphology induce to consider a levee breach in this zone still possible today. The other scenarios considered are about Dora Baltea river, one of the main Po tributaries. Inside the river valley is located a high risk industrial plant that was moderately damaged during the recent floods. The sudden breaking of a railway embankment, crossing the river just upstream the industrial area, would create an extremely dangerous additional flood with a high potential risk for the site. The flooding scenarios were numerically simulated with a 2D mathematical model based on Saint Venant equations solved by means of the well known McCormack finite difference scheme. When possible, a calibration of the model parameters on the basis of the available information about recent and historical events was performed. The results of the mathematical simulations have been used for the contouring of flooding maps for risk assessment and for the design of protection structures.