Green infrastructure measures as a strategy to adaptation of flooding risks in the Iguaçu-Sarapuí river basin, Rio de Janeiro, Brazil

 

Extreme weather events and the occurrence of hydrological disasters have intensified and grown into environmental challenges in many Brazilian cities. Given the current climate crisis scenario and the escalating frequency and magnitude of extreme events, it is imperative to not only implement prevention and mitigation measures but also to embrace strategies for disaster adaptation. This article aims to explore green infrastructure solutions that can mitigate flooding impacts in the Iguaçu-Sarapuí river basin, situated in the Metropolitan Region of Rio de Janeiro state, Brazil. To achieve this, we analyzed precipitation thresholds for the basin over each decade (from 1980 to 2020) using boxplots and quantile techniques, and assessed the impacts based on Civil Defense data from cities within the basin - institutions which are fundamental to disaster risks management. Additionally, we utilized Landsat data to map land cover, focusing on detecting changes in wetlands and flooded areas of the basin to identify correlations between these changes, the intensification of extremes, and the severity of impacts. Preliminary analysis of the study area revealed that extreme rainfall events and land use characteristics have contributed to flooding, leading to a range of environmental and social consequences including loss of life, economic damage, and displacement of populations. The expansion of urbanized areas and reduction of green spaces have notably decreased infiltration zones capable of capturing rainwater, consequently increasing surface runoff within the basin. Over the decades, local governments have predominantly favored gray infrastructure measures in the basin, leading to significant growth in paved and impermeable surfaces. Despite the implementation of flood control measures, the issue persists nowadays.