Urban floods are becoming a great concern of growing cities. Urban growth pressed by poverty and social drivers, together with possible climate change, may pose difficult challenges and increasing risk to safety and urban livability. In the face of this growing risk, urban drainage management is being pressed to move towards a flood risk management approach and that builds city resilience, or the capacity to continue functioning even in future hazardous conditions. In this context, this study proposes the development of an integrated Flood Resilience Index, departing from mathematical modelling tools and flood risk concepts. The Flood Resilience Index was built to support decision-making process in choosing design alternatives that improve flood control responses in future scenarios that surpass design standards. This way, flood control design decisions would be made under a quantitative assessment of the performance of a design alternative on potential flooding events in the long term. Flood Resilience Index was successfully tested in a watershed in the metropolitan region of Rio de Janeiro/Brazil where there is uncontrolled urban growth. It identified the best alternative to be a combined approach including sustainable urban drainage measures with river restoration techniques. When looking to the city centre area, this alternative scored a Flood Resilience Index of 47 over 100 against a conservative alternative of a dam, which only scored 20.

Urban flood modelling has been evolving in recent years, due to computational facilities as well as to the possibility of obtaining detailed terrain data. Flood control techniques have also been evolving to integrate both urban flood and urban planning issues. Land use control and flow generation concerns, as well as a set of possible distributed measures favouring storage and infiltration over the watershed, also gained importance in flood control projects, reinforcing the need to model the entire basin space. However, the use of 2D equations with highly detailed digital elevation models do not guarantee good results by their own. Urban geometry, including buildings shapes, walls, earth fills, and other structures may cause significant interference on flood paths. In this context, this paper presents an alternative urban flood model, focusing on the system behaviour and its conceptual interpretation. Urban Flood Cell Model-MODCEL is a hydrological-hydrodynamic model proposed to represent a complex flow network, with a set of relatively simple information, using average values to represent urban landscape through the flow-cell concept. In this work, to illustrate model capabilities, MODCEL is benchmarked in a test proposed by the British Environmental Agency. Then, its capability to represent storm drains is verified using measured data and a comparison with Storm Water Management Model (SWMM). Finally, it is applied in a lowland area of the Venetian continental plains, representing floods in a complex setup at the city of Noale and in its surroundings.