Portsmouth and Hull will have to plan Retreat, Attack or Defend strategies to avoid devastation from rising sea levels, a study by Building Futures and the ICE has found.
The coastal cities of Portsmouth and Kingston upon Hull will have to deal with rising sea levels by retreating inland, creating inhabitable defence structures or building out into the sea, according to new research by the Royal Institute of British Architects (RIBA) think tank Building Futures and the ICE.
A report launched today by the two bodies, entitled Facing up to Rising Sea Levels: Retreat, Defend, Attack? proposes three scenarios for each of the two cities, looking at proactive responses that could mitigate the threat of floods from rising sea levels.
The Retreat scenario sees the cities moving their lines of defence inland, allowing water to occupy previously protected city areas. Retreat involves letting water in among urban spaces to create new habitats and water storage, said Halcrow maritime project director Ben Hamer. “It is often seen as a controversial, negative approach, almost giving up. But it needn’t be,” he said.
The Defend approach sees flood defence systems being built and made commercially viable to attract private investment. These types of defences are familiar ones including tidal gates for Portsmouth which were “pinched” from Rotterdam, said Hamer, as well as less familiar “living walls” which could be sold to developers to be developed for profession or recreational purposes.
And the Attack scenario sees cities building out into the water via stilted and floating structures, alleviating pressure for living space and employment for a growing population. This approach allowed RIBA to run free with ideas and ask “How can we actually live among this water?”, said Hamer.
“People live in Portsmouth to enjoy the watery experience. So why not take that further?”
Ben Hamer, Halcrow
These ideas are currently happening abroad in Dubai and the Netherlands, said Studio Egret West partner David West, and are likely to enter common parlance within the next 20 years.
West predicted Attack-style measures could make cities more attractive. “I’d really want to go to Hull to experience this,” he said of the city’s potential stilted and floating ‘rigs’. “It’s a straightforward maritime living experience.” For Portsmouth the team designed inhabited two-tier piers. “People live in Portsmouth to enjoy the watery experience. So why not take that further?,” he said.
The case studies are idealistic and were approached as if there were no financial or bureaucratic limitations, said Hamer. They tried to take a positive attitude towards the problem, concentrating on benefits rather than losses, and took into account what could be done within the flood schemes to attract new investment and new revenue streams.
The Retreat scenario for Hull was even envisaged as a watery city “something similar to Venice”, with the historic centre defended and the surrounding area flooded, creating an island. The idea could “really create that excitement, that sense of ‘wow’,” said Arup rivers and coastal director David Wilkes. “I think it could create a fantastic potential destination.”
Sea level rises, landmass sinks and an increase in storm frequency and intensity all contribute to the threat of flooding, said the report. Climate change projections show that we could see sea level rises of as much as 1.9m by the year 2100.
The full project, including sketches and details of the proposed ‘new cities’, will be exhibited at the Building Centre, London until January 29, before travelling to Portsmouth from February 15 to 27 and then Kingston upon Hull from April 15 to 28. The report can be downloaded at http://www.buildingfutures.org.uk
- For more information on the study, see NCE’s flooding special issue on January 28.