Flood risk is generally composed of two parts: the probability of happening a hazardous event and its consequences. The first part is the source of risk and it is mainly given by the flooding magnitudes, although flow velocities and flooding permanence may play important roles. The second one reflects the vulnerability of the socioeconomic system exposed to flooding. Three aspects can represent vulnerability: exposure, susceptibility and value. Additionally, resilience can work to diminish vulnerability, incorporating the system responsive capacity. However, it is usual that risk assessment considers only the direct damage of flooding, tending to prioritize areas with high potential losses using an economic-based approach. This approach can exclude socioeconomically vulnerable communities from receiving proper attention and consequent investments in flooding mitigation measures. In this context, this paper presents an index to measure the Socioeconomic Recovery Capacity of urban areas prone to flooding through a multi-criteria approach, contributing to knowledge by introducing a social bias into flood risk discussion. The Flood Risk to Socioeconomic Recovery Capacity Index (Ri-SoRCI) considers the relative potential damage of flooding events, based on the capacity of the affected inhabitants to recover from losses. The Ri-SoRCI represents a socioeconomic parcel of the flood risk, through two indicators. The first represents the economic recovery capacity of an impacted region. The second indicates the region’s social vulnerability. The Ri-SoRCI was applied to the Canal do Mangue basin, in Rio de Janeiro, Brazil, supported by an environmental modeling tool able to simulate flooding phenomena with an integrated approach. The result shows the risk variation for different areas, from the socioeconomic point of view, subsidizing decision-making for public investments and allowing the construction of sustainability indicators to assess multiple scenarios. The case study validated the proposed index.

INTRODUCTION

The urban population of the world has been growing rapidly over the last years, having increased from 30% in 1950 to 55% in 2018. By 2050, the world’s population residing in urban areas is projected to be 68% (DESA/UN-WUP, 2018). The current number of people at risk from flooding is about 1.2 billion and, by 2050, this number rises to 1.6 billion, nearly 20% of the world’s population (WWAP/UN-Water, 2018). Urbanization associated with changes in land cover results in significant increase of impervious areas and decrease in vegetated surfaces, heavily modifying the characteristics of the surface runoff (Goonetilleke et al., 2005), increasing peak flows and stormwater volumes (Barbosa et al., 2012). Such effects associated with a forecasted increase in the precipitation intensity, caused by global climate change (Meehl et al., 2007), can intensify the stress on drainage infrastructures and increase flood hazards (Hoegh-Guldberg et al., 2018), expanding flood prone areas (PetitBoix et al., 2017). The increased flood risk encountered in today’s cities is mainly related to changes in land use and to the intense process of urbanization (Gogate et al., 2017).