Flooding hazard mapping in floodplain areas affected by piping breaches in the PoRiver, Italy

In the recent years the flood--related risk is increasing worldwide being inundations among the natural disaster which induces the maximum damage in terms of economic losses. In this study a methodology to map the flooding residual hazard due to levees 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 1D and 2D hydrodynamic models. The methodology is applied considering 96 different locations and sizes of breache 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 limit a $100 \, \mathrm{km^2}$ study area. The influence of obstacles to the flood propagation and consequent hazard mapping was investigated, taking into account several standard criteria to map flooding hazard in different European countries. The results obtained from this study 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, levees fragility and to the presence of topographic obstacles. All these details should be taken into account in land planning and flood risk management.