̽��ֱ�� of Cambridge - Ed Barsley

Waterworld: can we learn to live with flooding?

lw355 — Fri, 03 Jun 2016 09:52:17 +0000

In December 2015, Storm Desmond hit the north of the UK. In its wake came floods, the misery of muddy, polluted water surging through homes and the disruption of closed businesses, schools and roads.

Rapid urban growth and progressively unpredictable weather have focused attention on the resilience of cities worldwide not just to extreme events, but also to heavier-than-normal rainstorms, and raised questions as to how flood risk can be managed.

There is of course no ‘one-size-fits-all’ strategy. For some areas, defence is a possibility. For others, retreat is the only option. “But for those unable to do either, we need to fundamentally rewrite the rule book on how we perceive water as a hazard to towns and cities,” says Ed Barsley, PhD student working with Dr Emily So in the Cambridge ̽��ֱ�� Centre for Risk in the Built Environment (CURBE). Barsley believes that adaptation and planning for resilience can provide a unique opportunity for increasing the quality of towns and cities (see panel).

Dr Dick Fenner from Cambridge's Department of Engineering agrees that resilience to water should be regarded positively. He is part of the UK-wide Blue–Green Cities project, which is developing strategies to manage urban flood risk in ways that also pay dividends in many other areas, through ‘greening’ the city. “We want to turn rainfall into a win-win-win event,” he says.

When it comes to dealing with floods, one of the major difficulties that many cities face is the impermeability of the built environment. In a city that is paved, concreted and asphalted, surface water can’t soak away quickly and naturally into the earth.

Newcastle city centre, for instance, is around 92% impermeable, and has suffered major flooding in the past. “ ̽��ֱ��‘flood footprint’ of the 2012 ‘Toon Monsoon’ caused around £129 million in direct damages and £102 million in indirect damages, rippling to economic sectors far beyond the physical location of the event,” says Fenner.

“Traditionally, cities have been built to capture water run-off in gutters and drains, to be piped away. But where is away? And how big would we have to build these pipes if the city can’t cope now?” he adds. ̽��ֱ��principal behind a ‘Blue–Green City’ is to create a more natural water cycle – one in which the city’s water management and its green infrastructure can be brought together.

Cities worldwide are already taking up the concept of ‘greening’, using permeable paving, bioswales (shallow ditches filled with vegetation), street planting, roof gardens and pocket parks. Green infrastructure benefits health and biodiversity, and can help combat rising CO₂ levels, heat island effects, air pollution and noise.

“Not only do they also provide a place for water to soak away,” says Fenner, “they can even create resources from water – such as generating energy from the water flow through sustainable drainage systems and providing places for amenity and recreation.”

All well and good but with a long list of potential ‘blue–green’ choices, and an equally long list of benefits, how do cities choose the best options?

One of the major outputs of the Blue–Green Cities initiative is a ‘toolbox’ for authorities, planners, businesses and communities to help them decide. Using Newcastle ̽��ֱ��’s CityCat model, the team assessed how well green infrastructures performed in holding back surface flows, and used novel tracer techniques to follow the movement and trapping of sediments during intense storms. Then they mapped the benefits in a geographic information system (GIS) to identify physical locations that are ‘benefit hotspots’.

̽��ֱ��tools were developed by evaluating the performance benefits of green infrastructure gathered from sites in both the UK and USA. As part of a recent 12-month demonstration study in Newcastle, a Learning Action Alliance network was set up with local stakeholders that has, says Fenner, led to new opportunities that reflect the priorities and preferences of communities and local residents.

Now, Newcastle City Council, the Environment Agency, Northumbrian Water, Newcastle ̽��ֱ��, Arup and Royal Haskoning DHV have combined to be the first organisations in the country to explicitly commit to a blue–green approach, as recommended by the research. ̽��ֱ��hope is that other local and national organisations will follow suit.

Embracing resilience, as these organisations are doing, is vitally important when dealing with natural hazards, says Emily So, who leads CURBE: “We should remember that flooding is a natural process and a hazard we need to learn to live with. It is often the disjointed configuration of the built environment that results in it being a risk to the communities. Our aim should be to design to reduce the impact of, and our recovery time from, this natural hazard.”

Fenner adds: “Continuing to deliver an effective and reliable water and wastewater service despite disruptive challenges such as flooding is hard, but vital; it requires continuous and dramatic innovation. In the future, we will see fully water-sensitive cities, where water management is so good that it’s almost as if the city isn’t there.”

̽��ֱ��Blue–Green Cities project is funded by the Engineering and Physical Sciences Research Council (EPSRC), involves researchers from nine UK universities and is led by the ̽��ֱ�� of Nottingham. A parallel project, Clean Water for All, funded by EPSRC and the National Science Foundation, connects the team with researchers in the USA.

Inset image: Ed Barsley.

Flash floods, burst riverbanks, overflowing drains, contaminants leaching into waterways: some of the disruptive, damaging and hazardous consequences of having too much rain. But can cities be designed and adapted to live more flexibly with water – to treat it as friend rather than foe?

We need to fundamentally rewrite the rule book on how we perceive water as a hazard to towns and cities

Ed Barsley

Artist's interpretation of existing (left) and adapted (right) responses to flooding

Flood risk as a driver for change

While the Blue–Green Cities project focuses on urban drainage at times of normal to excessive rainfall, Ed Barsley is more concerned with helping communities consider the consequences of extreme events.

“Floods are devastating in their impact and flood risk is often seen as a burden to be endured,” says Barsley, “but future proofing and planning for resilience can and should be used as a driver for increasing the quality of buildings, streets and neighbourhoods – a chance for exciting change in our cities.”

As a case study, Barsley is using the village of Yalding in Kent, which has endured physical, economic and psychological impacts as a result of flooding.

He looked at how each house in the village prepared for and was affected by its most recent flood, its location and building material, and even its millimetre threshold height; and then he looked at future flood risk scenarios. ̽��ֱ��result is a methodology for assessing resilience that can be used to help inform and plan for adaptation, and is transferable to other communities large or small across the UK and worldwide.

“When we communicated the risks to the community, we found that resilience means different things to different people. Understanding priorities can help them tailor their own strategy to be contextually appropriate,” explains Barsley, who is special advisor on flood risk in the South East to Greg Clark MP, Secretary of State for the Department for Communities and Local Government.

For homes in which resistance measures like flood barriers will be overcome, one option might be to regard the lower floor as a sacrificial space – an area that can be flooded without disrupting waste, power or water. In Yalding, there are examples of homeowners who have done just this and added an extra storey to their homes.

“I’d like to see resilience rewarded and for us to begin to live with water in a different manner. Embedding long-term resilience has huge potential for creating vibrant and enriching spaces.”

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Good tidings for coastal communities

sj387 — Wed, 23 Oct 2013 09:00:49 +0000

Flooding from rising sea levels and extreme weather events is a major global issue, and the UK is no exception. According to the Government’s 2012 Climate Change Impact Risk Assessment, flooding is the greatest threat facing the UK today.

̽��ֱ��UK’s current strategy for coastal defence is largely reliant on rigid structures such as sea walls. Many of these are reaching the end of their design life, and proving disadvantageous in terms of cost, restrictive access to the sea and limited capacity to adapt to rising sea levels.

As for the longer term, the Future Foresight flood research project commissioned by government and published in 2004, concluded that the government’s 100-year shoreline defence plans were not adaptive enough to cope with changes expected within the next 15 to 30 years.

But how can walls and buildings – which we take for granted as solid, enduring structures – adapt to a landscape that is gradually changing from firm ground to wetlands to sea? Does such an adaption require a sea-change in our own attitudes to permanence in our built environment?

Ed Barsley, who completed a Master’s in Architecture and Urban Design last year in the ̽��ֱ�� of Cambridge's Department of Architecture and has now started a PhD, believes it does, and has come up with an adaptive, flexible approach to coastal flooding as innovative in design and technological terms as it is sensitive in cultural ones.

“I aimed to design a town that is intrinsically able to inhabit this increasingly flood-prone landscape,” he said. “It is characterised by two distinctive features. ̽��ֱ��first is a multi-layered threshold that combines soft and hard defences. ̽��ֱ��second is that every one of these thresholds is permeable by the sea.”

Barsley based his study in the town of Par near St Austell, inspired by a year spent building and designing eco-houses in Cornwall. Shortlisted for the Government’s now defunct Eco-town scheme, Par has been earmarked as a future key commercial and transport hub for the region. Yet it is at high risk of flooding.

Barsley’s concept starts not in the town itself, but out at sea. Wave attenuation devices would divert the waves’ energy, and harness it to power the town. A zone of coastal nourishment, created by spraying sediment on the sea bed, would then graduate the force of the waves and help dissipate their power. Next, a series of interconnected saline lagoons would help to further reduce the waves’ crest height and velocity, as well as provide vital wildlife habitats.

It would only be at the harbour that the sea meets a wall – and one with a difference. “My sea wall, which also acts as a social causeway, is perforated, its apertures work to diffuse the flow of the waves before they enter the harbour,” said Barsley. ”It has been designed to provide access to the water’s edge at a variety of height levels depending on the tides. Like the Thames Barrier, it could lock down and close up during extreme weather conditions.”

̽��ֱ��town itself is designed on the same principle as the permeable sea wall. “Buildings designed to act as buffers are juxtaposed with ones designed to let the water through, so as to enable the people of Par to maintain use of some buildings during a flood event” said Barsley. “Furthermore, because the apertures of the porous buildings are smaller at the front than at the back, the varied configuration of buildings would mean that the streets themselves act like the sea wall, further attenuating the turbidity of the water.”

Par is situated on ground that slopes up from the sea. ̽��ֱ��planning of Barsley’s town takes advantage of this. Organised on the basis of phased inhabitation zones, a range of street levels provides shelter and access routes, with essential services on highest ground.

This results in a main high street that is not only a refuge but is quintessentially Cornish in style and atmosphere. It is peppered with lateral access routes – narrow twisting lanes, winding staircases and inclines – that lead down to the harbour and afford tantalising glimpses of the sea. This charming, higgledy-piggledy style (or ‘Cornish vernacular’ as it known to architects) has emerged from Barsley’s strategic response to the need for resilience, rather than being a pastiche.

Despite its resilience, large portions of Barsley’s town would, eventually, become submerged: current data from the Intergovernmental Panel on Climate Change predicts that Par will be flooded on a daily basis by 2100. Barsley’s design caters for a future beyond this point. “Once submerged,” he said, “the town as a whole would form a major water-calming device in the same way as the other permeable thresholds, by both obstructing and attenuating the waves. As wetlands form in the area behind the town, the water would, I hope, be sufficiently calm to accommodate floating homes and amphibious technologies proven in their efficacy on still water, but unsuited to choppy sea-water.”

̽��ֱ��fundamental principle behind Barsley’s design for Par is that it should enable its residents to live in harmony with the ebb and flow of the sea. To an extent, they already go with the flow: the tides in Par fluctuate by 4.5 metres on an average day.

As well as adapting to the tides in pragmatic terms, however, Barsley believes that a fundamental shift in cultural attitudes towards the idea of possession of property is needed, because gradually, but inexorably, the sea is re-possessing the land. So Barsley’s design is based on the assumption of a policy of 50-year leasehold land parcels to underpin the strategy of Phased Inhabitation Zones. “A ground floor unit by the waterfront might start off life as a café or an artist’s studio,” he explained, “but after 50 years might need, for instance, to turn into a boatshed or a store. And at some point that unit will have to be abandoned and left to function as a defence threshold. We have to change our attitudes towards possession and risk, and stop fighting a losing battle with nature.”

Barsley begins his thesis with H G Wells’ prescient warning written in 1945: ‘Adapt or perish, now as ever, is nature’s inexorable imperative’. Barsley, and his fellow students and graduates of the Department of Architecture at Cambridge, are responding to the challenge.

Koen Steemers, Professor of Sustainable Design and Head of the Department of Architecture, said: “Ed’s project exemplifies design research that builds on the latest multidisciplinary research expertise to synthesise and test an imaginative design in response to pressing environmental issues. Because of the real potential application of such projects, recognised by the architectural profession, developers and policy-makers worldwide, we are now looking into setting up an enterprise advisory scheme to help realise such innovative and necessary visions of architecture.”

You can find more information about the pioneering work of students in Architecture and Urban Design including details of Ed Barsley’s project.

̽��ֱ��sea sustains life but also threatens it. An innovative design concept by Ed Barsley aims to contend with rising seawater by welcoming it into our coastal settlements.

We have to change our attitudes towards possession and risk, and stop fighting a losing battle with nature

Ed Barsley

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