Retrofit of Sustainable Urban Drainage (SUDS) in CBD for improved flood mitigation

Flood damage was estimated to cost A$20bn in Australia in 2011 and in 2007 in England flooding cost businesses £0.75bn. Surface water flash flooding has been driven by higher incidence of intense pluvial events; the lack of permeability in high-density areas; and the inadequacy of Central Business District drainage systems constructed to cope with different weather patterns and buildings. In the light of future uncertainties, continued reliance on piped drainage systems is creating unsustainable demands for ever-greater capacity, or the creation of underground storage facilities. As an alternative to expanding the existing grey infrastructure Water Sensitive Urban Drainage (SUDS) in are being advocated and legislated for. This research examined the potential for mitigation of pluvial flooding in CBDs through retrofitting of WSUDS. Two case study areas explored the challenges and opportunities for retrofit of WSUDS in cities with varying climate zones, urban design and governmental regimes. The contribution is to provide empirical data and knowledge in the emerging area of retrofit of WSUDS and provide material to build capacity to contribute to improved drainage and flood mitigation for commercial property. Software was developed to model the Bureau of Meteorology data of actual flood events. The significance of this research is that it shows that retrofit is sometimes needed outside flooded areas. It was shown that stormwater flooding can be slowed significantly by wide-scale retrofit and that policy makers could save money and disruption to city inhabitants through adoption. It provides a framework for others to follow to examine retrofit potential in their cities