A framework for assessing flood risk responses of a densely urbanized watershed, to support urban planning decisions

This study aims to provide a framework to analyse future flood scenarios considering the effects of three main drivers of flood aggravation: climate change (rainfall intensification and sea level rise); unplanned urbanization; and poor maintenance of urban drainage systems. These stressors were chosen because they represent the aggravation of a natural phenomenon, the urban sprawl effects and the degradation of the drainage system. This analysis intends to make it clear what the main drivers of increasing risks are. Subsequently, a uchronic scenario is developed to analyse how adequate urban planning and infrastructure provision can contribute to a sustainable and resilient city regarding flood alleviation. The method is supported by hydrodynamic simulation. Results demonstrate that precarious urban growth without providing adequate infrastructure coverage can be even more dramatic than climate change. Otherwise, the uchronic scenario demonstrates the benefits of adequately planning cities in a sustainable way, giving lessons to this process.