Hydraulic design model of underground bioretention system: a source control measure for wet weather urban stormwater management

The conventional practices of urbanization, land use strategies and stormwater management are considerably increasing the risk of wet weather flooding, downstream erosion and water pollution. To minimize the water pollution problem associated with the urban development various concepts of low impact development are being implemented. The city of Toronto has installed an underground bioretention system at Queensway Avenue. The hydraulic design criteria and specification of the underground bioretention system are not yet well developed. Hydraulic design model is developed using five mass balance equations of the five components of bioretention system. All design water depth variables of the bioretention system are solved simultaneously using Matlab program. An application of the model in Toronto is included to illustrate the design of the underground bioretention system.