Water damage

Atkins | 23 Jul 2015 | Comments

In the UK, where flooding is commonplace, the 2003 Water Act included provisions requiring dam owners to write on-site plans detailing how to react in the event of emergencies. Inundation mapping has been carried out in England, with Scotland and Wales likely to follow. How are these measures making a difference? And what could other flood-prone countries learn from these actions?

In 2007, 13 people lost their lives during severe flooding across the UK, prompting the government to review the country’s defences. Atkins’ director and dams specialist Andy Hughes consulted with Sir Michael Pitt on his report, which recommended a risk-based approach and the allotment of funds to local authorities with higher risk dams to write off-site plans outlining flood responses and how to evacuate affected populations.

“The whole profession has upped the ante,” says Hughes. “We’ve become more knowledgeable and proactive rather than reactive. We are able to have stronger tools that allow us to be able to manage situations better, rehearse and think about the consequences of failure a lot more than has been the case in the past.”

The structural engineering analysis of dams is now more thorough than ever before and young sciences are deepening the industry’s knowledge of possible outcomes in the event of disasters. Advances in soil mechanics, which looks at the behaviour of different types of earth, particularly its erodibility, have helped experts to predict with greater accuracy how infrastructure assets will endure over time. Coupled with an understanding of the dam control systems that can be vulnerable to cyber-attack, our resilience teams can provide a total integrated resilience solution for communities.

Mike Woolgar, market director for the water division at Atkins in the UK, believes the biggest change in recent years has been from a defensive to a risk management mindset.

Disaster mitigation is not a binary issue. If flood walls are built to protect against a 100-year event and a 200-year event occurs, some water will breach that defence. Some parts of the world are guaranteed to face disasters, so it’s a case of preparation and resilience rather than prevention.

“There are certain measures that can be taken to make sure that, when the damage hits, it’s not something you can’t recover from,” says Woolgar.

Holistic care

There is now an overall awareness of disaster preparedness and focus on resilience, consisting of mitigation and escalated recovery/reconstitution. Without proper forethought, planning any new developments can increase unexpected risks, even for areas that sit miles away.

For example, in the past, the economics of building a bridge over a river meant that they should be a short as possible. This was intended to save money, but, in many cases, it created pinch points, stymied flow, increased the risk of flooding upstream and reduced the access to many critical facilities if breached or closed.

In 2009, the Environment Agency began publishing catchment flood management plans (CFMPs) for each of England’s river basin districts to plot out who and what was at risk of flooding, whether that be residential housing, businesses, bridges, transformers and so on.

Taking a holistic view of resilience, where all hazards are addressed, offers a better understanding of the unforeseen consequences of building new developments, and helps to show where to avoid the accretion of people and infrastructure.

Beyond the UK

This is especially important in less developed countries that are undergoing vast economic and population growth.

To that end, Atkins has been working closely with the Southern African Development Community – an intergovernmental union of 15 nations that stretches as far north as the Democratic Republic of the Congo – as well as other countries on the continent to review how flooding may affect urban areas as well as rural populations, to predict impacts of different events and to determine what plans can be made to prevent flood damage, to limit construction in at risk areas and to support more rapid recovery from extreme events.
In Kenya, part of that work has involved raising people’s awareness of their own impact on their surroundings. “As the population has grown, more and more land has been put under the plough,” says Woolgar of those farming along the River Nzoia, which flows into Lake Victoria, Africa’s largest lake.

“If you don’t manage land with an understanding of drainage and flooding, you lose sediment. Sometimes it runs into the lake and sometimes it just sits in the river. When the river flow drops, water percolates down through the sediment and flows beneath it and then hydraulically compacts the sediment, making it harder. So the next flood that comes along doesn’t wash much of that away and you gradually get more deposits in the river, reducing capacity and increasing flooding.”

Woolgar explains that it’s important to help others understand such problems and – more importantly – their contribution to the solutions, rather than simply give instructions.

“A lot of risk reduction is about how you help the world’s most vulnerable people protect themselves.”

COMING SOON: Disaster resilience in the United States.

You can read more from Mike Woolgar here, and if you’d like to receive more articles like this in a regular monthly newsletter, sign up here.

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