Impermeability Rate Analysis for In-Line Detention Reservoirs—Introducing Multiple-Use Green Reservoir in the Urban Environment of São Paulo, Brazil
The watershed of Verde Stream, located in São Paulo, Brazil, is the object of projects that aim to minimize flood events’ damage, due to high slopes, consolidated urbanization, and few available areas for detention reservoirs. A locally well-known alternative for minimizing flood impacts is the Abegoária Reservoir. Despite its hydraulic benefits, population is resistant to its construction, allegedly associated with the imperviousness of green areas and the loss of space for social interaction. This study considers a new reservation approach that preserves permeability and multiple use of space, serving as both flood control system during rainy season and recreational area during dry periods. The average imperviousness rates were evaluated for the current scenario and two other reservoir conceptions, considering different types of ground coverage. Results showed that the presented reservoir would promote an increase in permeable surfaces by 35%. Average impermeability would only be increased if an impermeable underground reservoir was implemented.