Hydrologic performance assessment of regulated and alternative strategies for flood mitigation: a case study in São Paulo, Brazil.

This study examines the hydrologic performance of conventional and low-impact development (LID) stormwater approaches when implemented as retrofit measures in a highly urbanised catchment (10.23 km2). A hydrologic-hydrodynamic model was proposed to simulate different implementation scenarios. Rainfall data and downstream water level observations between 01/2016 and 02/2019 were used to calibrate and validate (0.77 ≤ NSE ≤ 0.97) the model for the current situation. The simulation of stormwater control, as indicated in the municipal regulation, involving on-site retention tanks at a lot scale, led to peak flow reductions of 5% for a 10-year design storm event. When the number of dwelling owners subjected to comply with the control measures was increased, a peak flow reduction of 18% for the same event was reached. Modelling tools can guide policy and rule-making processes from a catchment management perspective, supporting the evaluation and improvement of strategies adopted in urban stormwater management. [ABSTRACT FROM AUTHOR]