Avaliação dos impactos das mudanças climáticas no sistema de drenagem urbana do município de João Monlevade, MG

Abstract

Floods are natural events typical of rainy seasons, which occur annually in several Brazilian cities. However, due to climate change, these events are occurring more frequently in urban areas, as their effects can be amplified according to the soil use and occupation of the hydrographic basin. Therefore, the removal of vegetation cover in Permanent Preservation Areas (APP), the occupation of river banks and the obsolescence of drainage systems are some of the factors that promote the increase in the number of floods. João Monlevade is a municipality in Minas Gerais State that fits this scenario, as it concentrates 99% of its population in its urban area, with 10% of this total being on the banks of water courses, such as the streams Carneirinhos, Areão, Loanda, Metallurgical and Tietê. Due to climate change, increases in the volume and intensity of rainfall are projected in the southeast region of Brazil, where the municipality is located. In addition, João Monlevade has a frequent history of flooding due to the inefficiency of its urban drainage system. Given this scenario, this study aimed to assess the vulnerability of the urban drainage system in the municipality of João Monlevade-MG in the face of a future climate change scenario. For this, the sub-basin analyzed in this study was delimited and its morphometric characterization was performed. In addition, the soil use and occupation were established and measured in order to elaborate a current diagnosis of the region's urban drainage system; also, the observed and simulated rainfall data (over an interval of 30 years) were obtained. A climate change scenario projected for the future, which represents high emissions of greenhouse gases, was used and, through rainfall data simulated with the dynamic downscaling technique applied in a global climate model, the vulnerability of the drainage system in the municipality was assessed from simulations with a hydrological model. In this way, it was possible to evaluate the volumes drained in the study sub-basin in the current and future scenarios using the HEC-HMS software. It was found that the municipality's drainage system is obsolete and is no longer able to meet the drainage demand generated by the rains, therefore, it is recommended that non-structural actions, such as the implementation of an alert system, based on rain duration monitoring, be taken.