Hidrologia e drenagem urbana na prevenção e mitigação de riscos hidrológicos em Belo Horizonte – MG: análise de sensibilidade e diagnóstico da eficiência de jardins de chuva como solução baseada na natureza
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Abstract
The municipality of Belo Horizonte, Minas Gerais, due to its rugged topography and high rates of precipitation and soil impermeability, faces significant challenges related to hydrological risks, such as flooding. In this context, rain gardens emerge as a sustainable, nature-based solution, promoting the retention and infiltration of rainwater, and consequently reducing surface runoff. This study analyzed the hydrological efficiency of rain gardens implemented in the Northern Region of Belo Horizonte, based on a sensitivity analysis that considered variables such as precipitation rates, soil infiltration rate, device area, freeboard, contribution area and surface runoff coefficient. For this, computational simulations were performed using modeling spreadsheets. The results of the sensitivity analyses and hypothetical simulations performed demonstrated that, although rain gardens are effective in retaining considerable volumes of rainwater – achieving efficiency above 40% in almost all cases analyzed, and even reaching 100% in some –, their efficiency is clearly affected by factors such as incorrect sizing (especially regarding the contribution area), inadequate maintenance, accumulation of waste, slope of the land where they are installed, and variations in rainfall intensity. The diagnosis in the city of Belo Horizonte revealed that the implemented structures have little efficiency, being less than 15% in the observed scenarios, since they are insufficient to serve large areas, as they are currently arranged. It is concluded that, in order to maximize the benefits of this compensatory technique, it is essential to adopt an integrated approach, which involves urban planning, continuous maintenance of the devices, data monitoring, engagement of the local community in the conservation of these spaces, and incentives for their implementation directly in residences, commercial and industrial areas, especially in locations where the permeability rate is low.
