̽��ֱ�� of Cambridge - Dick Fenner

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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Safe water solutions

lw355 — Mon, 01 Nov 2010 15:38:27 +0000

Almost 900 million people worldwide lack access to safe water; polluted lakes and waterways diminish livelihoods and health; and 2.6 billion people (almost half the population of the developing world) lack access to adequate sanitation¹ .

In Cambridge, research groups from several disciplines are working in regions worldwide where dirty, polluted and inadequate supplies of water make drinking, cooking and cleaning an everyday challenge for the communities who live there. We take a look here at some of their solutions.

Water cleaning with mussel power

Zoologist Dr David Aldridge is a keen advocate for the amazing abilities of mussels to clean up water. His work in China is using these remarkable organisms as cheap and sustainable water filters to improve water quality and, as a result, it is hoped that a local industry will develop to farm them.

China’s Lake Dianchi was once a rich haven of aquatic species but increasing levels of pollution from a cocktail of fertilizer run-off, sewage and the effluent from factories has caused a huge deterioration in water quality. ̽��ֱ��water is undrinkable and a hazard to those using it for washing, and the native aquatic wildlife has all but died off. Where once underwater visibility was over 10 metres, on a good day it’s now a mere 30 cm.

Using a set-up that could be replicated in many of the world’s polluted freshwaters, Dr Aldridge from Cambridge’s Department of Zoology and colleagues at the Chinese Academy of Sciences have deployed specially bred giant mussels – once native to the lake – in experimental enclosures along the lakeside.

̽��ֱ��mussels filter 50 litres of water a day, removing algae and suspended particles. ‘In just a few months,’ he explains, ‘not only did the water become clearer but native plants suddenly began to emerge from seeds buried for decades on the lake bed. These, in turn, provide habitat for insects, and then fish, and the system stabilises back to clearer water.’

One challenge has been the tendency of people living locally to eat the mussels. ̽��ֱ��team’s solution has been to turn to pearl farming to encourage the community to sustain the mussels in the lake. Chopsticks are used to insert a tiny bead of shell into the mussel, around which a pearl is formed. Recognising the potential impact of this idea on bolstering local industries, the World Bank awarded Dr Aldridge a Development Market Place Award to continue the work.

Dr Aldridge is also developing a means by which local authorities and managers of waterways can check the health of freshwater in their region, reducing the need for difficult and costly chemical testing. ‘We’re using the biology of the lake as an indicator of water quality. ̽��ֱ��number and type of organisms, or biotic index, provides a useful indication of the state of the water they live in. ̽��ֱ��guide book we are creating will enable users armed with only a hand net to monitor the condition of water in their province.’

Healthy water for households

Many people who lack access to safe water live in regions where conventional methods for supplying drinking water through water pipes are simply not possible or cost-effective. For these people, the alternative is to use household water treatment and safe storage systems (HWTS) based on chlorination, solar disinfection, ceramic filters or biosand filters.

As part of Dr Douglas Crawford-Brown’s wide research interests in water policy, he has been examining the effectiveness of reducing microbes in drinking water using low-cost HWTS in the developing world. As Executive Director of the Cambridge Centre for Climate Change Mitigation Research, in the Department of Land Economy, his research interests have an environmental perspective: ‘ ̽��ֱ��problem of ensuring safe water provision in the face of environmental change is a global one. But for developing countries, where large investments in infrastructure are not possible, it’s a massive concern.’

His work has been in collaboration with colleagues Dr Mark Sobsey and Dr Linda Venzcel at the ̽��ֱ�� of North Carolina, from which he moved two years ago, and Dr Christine Stauber at Georgia State ̽��ֱ��. Dr Crawford-Brown’s role in the long-term project has been to model the predicted human health impacts so that they can be compared against field epidemiological data in the Dominican Republic, Ghana, Honduras and Cambodia.

‘Our results show clearly that there is significant reduction in microbes, but also a residual concentration that can be quite difficult to remove,’ he explains. ‘In one project funded by the International Rotarians, we found that a simple sand filtration HWTS in the Dominican Republic halved the incidence of diarrhoeal disease, a major cause of death among infants in poor communities worldwide.’

Given that affordability of water systems is a critical regulatory issue, his research has also looked more widely at health–health trade-offs. ‘Trade-offs occur when the costs of water treatment in poor communities cause them to re-allocate limited finances, often away from buying medicine, unless public programmes are brought in to provide healthcare. Our goal is to provide policy makers with the evidence on which to base decisions on risk and in allocating budgets.’

Improving outcomes

Having worked for several years in rural Nepal trying to implement the use of water filtration units, Tommy Ngai from the Department of Engineering knows only too well that, despite their benefits, the adoption and continued use of HWTS is not always straightforward.

For the past four years he has been investigating how to scale up the dissemination of HWTS. Working with Dr Dick Fenner in the Centre for Sustainable Development in the Department of Engineering, his research has taken him to Nepal, southern India and Ghana, where he has carried out extensive interviews with project management staff, community workers, government officials, shopkeepers and household end users.

‘It’s not uncommon for communities either to not take up HWTS or for the equipment to be found lying abandoned a year or so later,’ he explains. ‘There may be a lack of awareness among potential users, or the devices may be too expensive to operate and maintain, or the supply chain unavailable, or there may be technical difficulties and ineffective post-implementation support.’

Ngai’s research has, for the first time, captured the big picture of the many competing factors at play – from the technical and financial, to the social and institutional. ̽��ֱ��outcomes are three programme-specific computer simulation models linking over 300 different variables. ̽��ֱ��models can help implementing organisations to appreciate the complexity of project management, to understand the interactions and consequences of any policy strategy and, crucially, to make recommendations for increasing the success of an HWTS programme.

‘Literally thousands of scenarios can be simulated in the model, whereas in the real world you can only try one strategy at a time,’ he says. ‘Comprehensive analysis showed that no single strategy will always work in all situations, and that some measures that have long-term benefits may at first appear counter-intuitive.’

One of the models has also been designed as an easy-to-use simulation game that can be run on a PC, allowing agencies and government officials to explore the effects of different potential intervention strategies concerning programme expansion, promotion, training, pricing and capacity building, and to predict adoption and sustained use of HWTS.

In his next post, as Director of Research Learnings at the Centre for Affordable Water and Sanitation Technology in Canada (www.cawst.org/), Ngai will be using his research to help NGOs and government policy makers to understand quickly how best to encourage sustained adoption of HWTS in their region.

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For more information about these projects, please contact Dr David Aldridge (da113@cam.ac.uk) at the Department of Zoology; Dr Douglas Crawford-Brown (djc77@cam.ac.uk) at the Department of Land Economy; Tommy Ngai (tommyngai@yahoo.ca) and Dr Dick Fenner (raf37@cam.ac.uk) at the Department of Engineering.

Research across the ̽��ֱ�� is helping to clean up water in regions around the world.

̽��ֱ��problem of ensuring safe water provision in the face of environmental change is a global one. But for developing countries, where large investments in infrastructure are not possible, it’s a massive concern.

Dr Douglas Crawford-Brown

Tommy Ngai

Water clarity improvement after filtration

Sanitation innovation

Ensuring access to safe water isn’t the only challenge; it’s also what you do with waste. An innovative study has come up with a prototype system that could improve sanitation in urban slums.

̽��ֱ��realities of high-density living in urban slums have made conventional approaches to improved sanitation practically impossible, with low-income families renting living space in tightly packed, unplanned settlements serviced by pit latrines.
Nate Sharpe’s research in the Centre for Sustainable Development has come up with a solution for emptying pit latrines in the slums of Dar es Salaam, Tanzania, although his findings should be applicable to many other similar cities around the world. ‘Pit latrines are filling up faster than ever and people are often forced to rely on unhygienic emptying methods,’ he explains. ‘If smaller amounts of the sludge could be removed more often, it becomes easy to transport – even on the back of a bicycle.’

Sharpe has designed a prototype bicycle-powered vacuum pump/tank system and a business model for small businesses to run a latrine-emptying service at a low enough price that even the poorest might be able to afford to make their latrine usable again. ̽��ֱ��next stage is to test the device in Tanzania and to put the device into production.

His research was completed as part of an MPhil in Engineering for Sustainable Development with Dr Heather Cruickshank, and is just one of around 35 similar projects annually that are finding innovative engineering solutions to a host of sustainability problems. Many focus on developing countries where, as Sharpe has highlighted, sometimes the solution lies not in the development of new technology but in the creation of a new business angle that works in the local community.

For more information about these and other projects, please contact Dr Heather Cruickshank (hjc34 AT cam DOT ac DOT uk).

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