Urban Resilience to Floods: Real Challenges and Misleading Myths

Flooding is one of the most challenging weather-induced risks in urban areas, due both to the typically high exposures in terms of people, buildings and infrastructures, and to the uncertainties lying in the modelling of the involved physical processes.In the last decades, European cities are increasingly facing challenges associated with urban sustainability and urban water issues.Floods are normally a consequence of extreme rainfall events, but they can also happen because of infrastructure failures.Climate change also leads to flood risk increase, due to hydrological alterations, including changing patterns of precipitation and rising sea levels.Hazard and risk assessment is an essential issue in the reduction of adverse effects of extreme events.Here, the term "hazard" refers to the occurrence probability of a potentially damaging event, while the term "risk" refers to the extent of consequent damages and losses.Several procedures, less or more detailed, are available in scientific literature for the assessment of hazard and risk maps, in most cases designed to provide maps or charts from the combination of probabilistic analysis of historical records and geographic information knowledge.In many countries, standard procedures are also available, mainly for planning purposes.The European Directive 2007/60/EC (Flood Directive) establishes the framework for the assessment and the management of flood risks.A crucial tool for the achievement of these objectives is the preparation of flood hazard and flood risk maps.This activity calls for an active involvement of all the stakeholders in developing flood risk management plans.