Efeitos da utilização de biorretenção em uma área urbana: análises quantitativas em função do código de urbanismo e edificações de Maceió-AL

Abstract

The accelerated urbanization process occurred in Brazil, which began in the 1950s, caused changes in social and environmental structures in the country, causing significant impacts on urban hydrology. The municipality of Maceió - AL, has in its Urbanism and Buildings Code (Municipal Law No. 5,593, February 8, 2007), guidelines that deal with a permeability rate area application to try to minimize impacts generated by urbanization, with requires a minimum value of 15% to total lot area, for lots areas bigger than 2,400 m², while lots areas less than 1,200 m² are exempt from this rate. It is important to highlight the residential occupation pattern growth to multifamily type (buildings), developed by the constructor sector, such occupation is associated with subsoil existence (usually for garages use), in which lot total waterproofing can occur (for those smaller than 1,200 m²). The objective of this study was to evaluate the quantitative impact of bioretention devices usage, for different device configurations and return period (10, 5 and 2 years), as an alternative to permeability rate application, predicted on Maceió’s buildings and urban planning code. This study used the PCSWMM model, which is widely used for urban basins. It was possible to observe peak flow reduction’s potential variations due different device’s configurations proposed, with reduction values between 4.32 and 72.61%, for different settings and return period. As for basin scale application, the result pointed to peak flow reductions for different scenarios. It was possible to observe the peak flow reduction when applying bioretention in smaller areas when compared to permeability rate application, with peak flow reductions of 43.55 to 23.10% when applying bioretention in 50 to 7% of the permeability rate area predicted, with a return time of 2 years. The result points to the possibility of useful lot area increasing to be used for other purposes, such as garage. Therefore, this study can serve as a subsidy to incentive such compensatory technique application, since it shows advantageous for constructors and flow control, since it makes possible tradable area and peak flow reduction generated by lot.