Water and The City Webinar

Jointly hosted by the UDG and the Landscape Institute (London Branch) and chaired by Paul Reynolds, this event explored how to deal with the climate emergency by making schemes sustainable and resilient for the long term. Louise Walker (CIRIA) outlined how to encourage best practice for SuDS practitioners. Images and tables highlighted the four pillars of good SuDS practice, which deliver water quantity and quality, creating amenity and encouraging biodiversity. Well-designed SuDS in urban areas can make better places with reasonable payback periods of about 12.5 years. Roger Nowell and Zac Tudor (Sheffield City Council) described how the city inherited problems with combined sewer systems polluting water courses and the terrible impact of the 2007 floods. This led to the promotion of a health and well-being policy with urban greening along the old ring road and green-blue garden spaces that increased biodiversity and softened the hard edges of this gritty Northern city.

Peter Mackey (Chapman Taylor Shanghai) introduced the concept of Sponge City – the city acting as a sponge in mitigating natural disasters – and illustrated it with with their competition-winning Chinese Xion’an Master Plan which used the existing river system to extend linear parks into the built-up areas. Excellent images demonstrated how storm water was cleansed and recycled along sponge corridors. A coastal example in sub-tropical Shenzen showed how typhoon impacts could be mitigated by sustainable sponge city defences, including floating mangrove islands. With a drainage engineer’s perspective, Owen Richards (McGregor Coxall) described how China’s sponge city methods were being used to cope with polluted lakes and extreme rainfall. China’s President Xi had announced funding for a project to transform 30 cities into sponge cities by replacing grey with green infrastructure. China’s massive urbanisation has consumed 6.6 billion tons of concrete in only 3 years; it will therefore require a paradigm shift for sponge city principles to begin to mitigate its impact.

Ian Lanchbury (Ramboll) illustrated ‘cloudburst’ resilience masterplanning examples from Scandinavia, Melbourne and New York. The 2009 COP 15 in Copenhagen set out a cloudburst events strategy to manage one-in-a-hundred year storms at the catchment scale, by investing in bluegreen infrastructure in synergy with other initiatives and to promote liveable city principles. Benefit-cost ratios of 1.8 showed good value for money investing in cloudburst masterplanning.

Most of these problems of managing water in rapidly urbanising areas might have been avoided if more city planners had read Ian McHarg’s Design with Nature (1969), which promoted principles of ecological planning using natural systems.

Malcolm Moor, architect and independent consultant in urban design and co-editor of Urban Design Futures (2006)