Assessment of Sustainable Urban Drainage Measures for Flood Mitigation in a Densely Populated Watershed in São Paulo, Brazil

Abstract

In light of the increasing adoption of sustainable urban drainage measures for flood control, driven by advances in the urban drainage field and, particularly, in downtown São Paulo, by the significant challenge associated with implementing large detention reservoirs due to the scarcity of open spaces within the watershed, this study investigates the hydrologic and hydraulic parameters that influence the rainfall–runoff simulation in urban areas using the PCSWMM model. Real-time telemetry data, including measurements from meteorological radar, rainfall gauges, and fluviometric stations, were employed for model calibration and validation. Historical images of São Paulo from the 1930s were used to assess the potential impact of promoting permeable surfaces within the basin on current design hydrographs and flood-prone area extents. Two future scenarios incorporating sustainable urban drainage strategies for flood mitigation were analyzed to evaluate their effectiveness, complemented by a sensitivity analysis to identify the parameters with the greatest influence on the simulated hydrographs. Results indicate that, even though sustainable measures significantly reduce flood-prone area extents, their performance is highly dependent on rainfall duration and return period. Consequently, an integrated approach combining conventional and sustainable strategies is recommended for managing design storms with longer durations and higher return periods.