Evaluating the hydraulic performance of stormwater management infrastructure with 2D modeling and in situ monitoring: Water Square Place des Fleurs-de-Macadam case study

Juan Esteban Ossa Ossa, Sophie Duchesne and Geneviève Pelletier


In situ monitoring and numerical modeling are essential activities to quantify the advantages and improve future designs of stormwater management infrastructure. This infrastructure can reduce runoff volume and alleviate sewer overflow problems in densely developed urban sectors. This project assessed the hydraulic performance of a water square called Place des Fleurs-de-Macadam located in Montreal, Canada. The water square is composed of a detention pond and bioretention cells that redirect and accumulate surface water from adjacent streets, enabling the infiltration of retained water and preventing excess water from surcharging the sewer system. The water square was evaluated with a 2D model in PCSWMM under different rainfall conditions, to better understand its hydrological behavior and to obtain an initial assessment of the site’s performance. Furthermore, in situ monitoring of the site was achieved by a flood test, in which a three-hour rainfall of 62 mm was simulated using fire hydrants, which is equivalent to a 100-year event for this area. During the test, inlet and outlet flows were measured by installing flow meters, and a visual inspection around the entire water square was conducted to verify water levels and flow paths. Results obtained during the flood test and the 2D modeling indicated that the water square and bioretention cells can effectively mitigate urban stormwater runoff. Indeed, for the event evaluated in the test, the studied stormwater management infrastructure reduced the runoff volume by 98%, with an outflow delay of 75 minutes. In summary, results indicated that the hydraulic performance of the water square Place des Fleurs-de-Macadam was very good.

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