Modélisation des effets de la végétalisation en milieu urbain sur les eaux de ruissellement dirigées à l'égout

Abstract

Many solutions exist to reduce the effects of urbanization which are damaging to the peak flow rate and water volumes of the urban drainage system. The Low Impact Development infrastructures, which are an integrated approach to stormwater management, attempt to capture the stormwater before it reaches the drainage system. The main goal of the study was to quantify the effects of LID on runoff water normally directed to the drainage system in an urban setting, looking especially at highly urbanized areas. To accomplish this, SWMM software was used to simulate the incorporation of several LID infrastructures (green roofs, porous pavement, swells, street planters) on Beaudoin street situated in the Southwest neighbourhood of Montreal. Different modeling methods were used, especially for the different infiltration methods (Green-Ampt, Curve Number) to simulate the LID (green roofs and trees) on SWMM 5. Five layout scenarios were created and simulated with different rain events (12 mm, 24 mm, 32 mm and 21 mm+11mm). Analysis showed that green roofs permitted a reduction of max flow rate of stormwater of 22% for the 12 mm rain and of 15% for the rain of 24mm. This reduction is at approximately 8% for the volume of the two rains. The reduction of max flow rate and volume is at 20% for the porous pavement regardless of the rainfall. With regards to the total surface occupied, the trees perform well with a reduction of 1% for only 77 m2 of planted trees. The porous pavement showed the best performance to surface area ratio. The green roofs and trees both are much less effective with wet soil with green roofs performing at half their previous results. The LID infrastructures are efficient at reducing the peak flow of weak rain but perform at much reduced rates with medium rainfalls and wet soil. The scenario that performed the best was the one that offered a mix of the different LID infrastructures. The study of other neighbourhoods with different typologies would allow more generalized conclusions to be obtained. Also, complementary studies on the effects of trees on rainfall would allow better quantification of the true effects of the trees.

Date	25 Jul 2011
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Frédéric Monette (Supervisor) & Mathias Glaus (Co-supervisor)