Urban Runoff Source Control Measures in São Paulo: Technical and Legal Aspects (PAP014718)

Código

PAP014718

Autores

Julio Fracarolli Canholi, Mario Thadeu Leme de Barros

Tema

Urban Floods

Resumo

New urban developments may cause serious inconvenience on urban drainage systems when their hydrologic impacts are not properly mitigated. Many cities around the world tried to minimize the effects of urbanization by implementing source control measures encouraged by regulations, laws or ordinances. In many cases, the introduction of this type of solution has led to adverse outcomes, not only because of the choice of the device, but also due to regulations control standards. This study evaluated four different urbanization scenarios in order to analyze São Paulo´s ordinance efficacy on controlling hydrologic impacts of new developments. Among these scenarios, the installation of micro reservoir and rain gardens were evaluated. Results showed that it would possible to attenuate peak flows from source controlled areas by 20%., and by 11% and 9% considering the contribution from the whole development of the catchment, respectively. When the location of the micro reservoir was changed, it was possible to double the attenuation efficacy. The use of rain gardens showed worse results for peak flow attenuation. However, these devices can reduce by 64% the number of runoff events from controlled areas, which are strongly linked to water quality. It was concluded that the existing law (municipal law 41.814/02 and state law 12.526/07) only partially meets its goal for flood control. The law presents a good opportunity to increase the effectiveness of urban drainage systems and its contents should be revised in order to allow non point source pollution control and urban river degradation.