Flood hazard maps for vehicles and pedestrians

Floods are responsible of many casualties, which, in developed countries, are often caused by the attempt to wade flooded roads by car or on foot. Experimental activities and numerical models clarified, from the mechanical point of view, the occurrence of the phenomenon of instability for vehicles and pedestrians in floodwaters. However, putting into practice this knowledge is still a subject for research. This work aims at demonstrating the capabilities of flood hazard maps for vehicles and pedestrians as a support for risk assessment and management. Flood maps are implemented with a full 2D numerical model, whose mesh is refined enough to capture the urban roads/building pattern. The stability of parked vehicles and pedestrians is assessed through a dimensionless diagram, which allows the selection of a specific target receptor (Arrighi et al. 2015, 2016). The method is applied to a district of the city of Genoa (Italy) affected by a flood in 2014. The inundation model reproduces the actual flood event (Silvestro et al. 2015, 2016), whose water marks have been used for validation. Hazard maps for vehicles and pedestrians are compared to georeferenced images and videos taken during and immediately after the flood, showing a good agreement, although qualitative. This application allows the identification of particularly hazardous zones, which after the analysis of variuos scenarios, can support civil defence actions and citizens’ education.