Study of Green Roofs: Green Roof Guidelines, Water Quality and Peak Runoffs
Professor WAI Wing-hong, Onyx (PolyU)
Abstract
The built environment characteristic of urbanized areas is comprised mostly of impermeable concrete surfaces which generate more stormwater runoff than rural areas causing flooding and water quality deterioration during rainstorms. This situation may get worse because a Hong Kong Observatory study has shown that the annual total rainfall over different regions of Hong Kong is on a rising trend. As the roof areas in Hong Kong represent one of the most underutilized spaces in the city, this study explores the feasibility of using green roofs as a means to mitigate peak runoffs and improve runoff water quality. The other objective of this study is to use experiments, numerical models and stakeholder surveys to obtain more local data and information for developing reliable green roof guidelines for the Hong Kong's unique climate conditions and building forms. Numerical models, such as Hydrus-1D for stormwater infiltration and runoff predictions and FLUENT for greenroof wind stress estimations, will be used. In-situ measurements of stormwater runoff and water quality are conducted at the Sludge Thickening House Extension at Sha Tin Sewage Treatment Works. The field measurements together with laboratory experimental results will be used to calibrate and verify the runoff model.
About the Speaker
Professor Onyx W. H. WAI is a Professor in the Department of Civil and Environmental Engineering of Hong Kong Polytechnic University (PolyU). He got his PhD in 1991 from the Ohio State University and joined PolyU in 1992. His research activities are primarily concerned with the fate and transport of sediment particles in water bodies. Recently, he has expanded his research focus to include urban eco-greening. His recent projects involve investigating the suitability and sustainability of eco-roofs and eco-flood channels in urban areas. He is the recipient of the 1989 ASCE Karl Emil Hilgard Prize. He is now the Chairman of the International Association of Hydraulic Engineering and Research (Hong Kong Chapter).
