Indicadores de fragilidade do sistema de drenagem urbana aplicados em microbacia do município de Itaituba-PA

Abstract

Considering that the Urban Drainage System (UDS) is designed for a given rainfall regime and that extreme precipitation events have become increasingly intense and frequent due to climate change, there is a need to evaluate the performance of these systems and identify their potential weaknesses. In this sense, this study presents a diagnosis of the macro-drainage of the Igarapé Oriundo microbasin, a small tributary of the Tapajós River that runs through the urban center of the city of Itaituba-PA, using System Fragility Indicators (SFI) categorized into 4 types: environmental, social, technical and institutional. To this end, a Systematic Literature Review (SLR) was initially carried out, using the StArt software and consulting the Scopus and Web of Science databases, to extract and select the indicators most used in the scientific community, with a view to analyzing and evaluating the weaknesses that impact the performance of urban drainage systems. The indicators were then applied, with weights assigned, to 6 points of interest (PI) along the Igarapé Oriundo, through on-site inspections that took place in 2 moments, with an interval of 1 year. In total, 20 indicators were evaluated, formulated from 10 articles resulting from the RSL. To characterize the weaknesses of each PI, the General Fragility Indexes (GFI) were calculated by adding the weights assigned to the IFS, which were classified as: very low, low, medium, strong and very strong weaknesses. In this way, it was possible to establish a point-by-point diagnosis and identify the main vulnerability, with the following being observed: medium fragility in PI-1 (source) and PI-6 (exutory), especially in the environmental scope; strong fragility in PI-2 and PI-3 (both partially urbanized), with emphasis on the technical and environmental parameters; and very strong fragility in PI-4 and PI-5 (both in areas with consolidated urbanization), with emphasis on the technical, environmental and social natures. All PI demonstrated worsening institutional fragility. Finally, it was possible to indicate, in a matrix of proposed solutions, possible mitigating measures that could be adopted in the microbasin, aiming to reduce the weaknesses found, highlighting: promulgation of the Urban Drainage Master Plan, creation of the Oriundo Urban Park, adoption of compensatory techniques and relocation of the marginalized population.