ASSESSMENT OF FLOOD HAZARD INDUCED BY LEVEE BREACHES IN THE MIDDLE PO VALLEY

Lowland areas protected by river levees may be subject to inundation in case of embankment failures, especially during extreme events. Therefore, the European Floods Directive (2007/60/EC) specifically requires that residual risk be included in the assessment of flood hazard and risk, in view of designing effective flood risk management plans. This paper presents a practicable approach for mapping the residual flood hazard in lowland areas, applied to the case study of the middle Po River Valley (Italy). By exploiting a fast and accurate shallow‐water model (PARFLOOD), fully two‐dimensional simulations of several hypothetical scenarios of breaching on the right river levee and of the subsequent inundations are performed for a flood event with return period of 500 years. The results of all scenarios are combined to obtain maps of maximum depths and velocities, representing the “worst‐case” conditions that can be expected at each location. The mapping of all floodable areas can be useful for identifying strategies to increase the resilience to flooding in these territories.