Flooding Hazard Mapping in Floodplain Areas Affected by Piping Breaches in the Po River, Italy

In recent years, flood-related risk has been increasing worldwide, being inundations among the natural disasters which induce the maximum damage in terms of economic losses. In the research reported in this paper, a methodology to map the flooding residual hazard due to levee failure events induced by piping in embankments protecting flood-prone areas is proposed. Ensemble simulations are used to account for uncertainties in location, geometry, and time-evolution of the levee breaches. Probabilistic flooding-hazard maps are generated combining the results of 192 inundation scenarios, simulated by using one-dimensional (1D) and two-dimensional (2D) hydrodynamic models. The methodology is applied considering 96 different locations and sizes of breaches occurred along a 23-km reach protected by the right levee of the Po River, the right levee of the Taro River, and the left levee of the Parma River, which delimit a 100-km2 study area. The influence of obstacles to the flood propagation and consequent hazard-mapping was investigated, taking into account several standard criteria to map the flooding hazard in different European countries. The results obtained from the research reported in this paper provide an example of a rational method to map the residual hazard in areas protected against flooding due to embankment-overtopping, taking into account uncertainties due to breach location, levee fragility, and the presence of topographic obstacles. All these details should be taken into account in land-planning and flood-risk management.