Effect of land use and low impact development measures on urban flood hazard: a case study in the Black Creek watershed

The number of flooding events in Canadian urban environments continues to increase, causing major environmental, economic and social consequences. This research uses the Black Creek watershed, located in southern Ontario, to investigate the impacts of urbanization on flood hazard and evaluate the effectiveness of various low impact development practices at reducing this hazard. A land use analysis indicates extensive urban growth between the periods 1949 and 2015, with extremely high imperviousness percentages existing today in the majority of the watershed. Historical hydrological simulations in PCSWMM show a significant increase in peak flows since 1949, but have now stabilized due to the limited land available for further development. Stormwater management ponds in the northern region of the watershed have helped control runoff from densely developed areas. Minimal stormwater management exists in the southern region, with low potential for implementation of large stormwater management features. Low impact development practices such as bioretention cells, infiltration trenches, permeable pavement, rain barrels, and vegetative swales were simulated in various scenarios to investigate their effects at reducing flood hazard. Results demonstrate that low impact development measures can effectively reduce peak runoff reduction rates by as much as 76% in smaller subcatchments for a 2-year storm event. This thesis provides insight into the capabilities of low impact development measures to improve flood hazard management and decrease flood hazard in urban environments