Urban flood resilience - A multi-criteria index to integrate flood resilience into urban planning

Climate change and increasing urbanization pose huge challenges in managing urban planning for a sustainable future. Intense urbanization resulting in the so-called mega cites aggravates floods by increasing the amount of impermeable surfaces and modifying flow routes. Statistics show that flood disasters are one of the most significant in terms of damages and losses. Urbanization rates are increasing rapidly and it is important to learn how to live with floods by alleviating their consequences, in the present and future. This concern points to the resilience concept. By including the concept of resilience in flood risk analysis and decision-making, urban drainage design moves towards sustainable drainage systems. This study discusses resilience in the flood risk contextWe considered three main drivers to define a quantitative measure of flood resilience: the capability of a drainage system to resist and provide its service continuously over time; the capability of an urban area to recover from flood losses; and the capability of urban systems to evacuate floodwaters and return to a functional state. Consequently, this paper describes how flood resilience can be modeled and spatialized by a multi-criteria index called Spatialized Urban Flood Resilience Index (S-FRESI). The S-FRESI composition (according to the resilience definition adopted) combines: the hazard characteristics and the system exposure and susceptibility, to represent flood resistance mapped over time; the ability for material recovery from losses caused by inundation, considering the income variable; and the functional capacity of the drainage system, represented by the flood duration. S-FRESI can be used to measure and visualize the changes in flood resilience attained by different flood control measures, as well as in future scenarios of population growth, uncontrolled urbanization or climate change. The index was tested with coherent and consistent results in the Dona Eugenia river catchment in Rio de Janeiro. Four different scenarios were formulated: (1) the current situation; (2) the current situation considering the implementation of sustainable flood control measures; (3) a future situation with the same infrastructure as today; and (4) a future situation with the considered flood control measures.