UBC Theses and Dissertations

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UBC Theses and Dissertations

Rainwater recycling on green roofs for residential housing : case studies in Richmond, British Columbia; San Antonio, Texas; and Toronto, Ontario Kong, Yuewei


Stormwater is the component of runoff that is generated by human activities, and has gradually become a key issue in achieving sustainability in urban environments. When vegetation and soils are replaced with roads and buildings, less rainwater infiltrates into the ground or is taken up by vegetation, and more becomes surface runoff. A greater area of impervious surfaces leads to increased stormwater runoff volume and velocity, and consequently increases the risk off looding and erosion. Being able to reduce stream flows and pollution of surface flows, green roofs are one technology that may help in alleviating this storm water crisis. This thesis developed a different and effective methodology for quantifying the effects of green roofs on stormwater runoff and calculating the runoff volume and rate for residential housing communities before and after applying green roofs. The method utilizes local climate data like rainfall and evapotranspiration rate, the water use properties of vegetation like crop coefficients of plants, and the areas of impervious surfaces; and then compares the different effects of green roofs in different locations having disparate climatic conditions. It was found that the best way to achieve zero runoff was to green a portion of the total rooftop area and disconnect all impervious surfaces. Implications of this methodology on city planning and site design and for future research are then discussed.

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Attribution-NonCommercial-NoDerivatives 4.0 International