How natural flood management can build resilience

Far from being a new concept, it is a little known fact that natural flood management actually dates back to the American War of Independence.

Launching a new report this week on the evidence behind natural flood management, the Environment Agency’s executive director of flood and coastal risk management, John Curtin, said it was Major General Horatio Gates, who formed the American Army Corps of Engineers back in 1778 who first developed the idea.

‘The American Army Corps of Engineers was formed during the American War of Independence,’ Mr Curtin told a conference in London organised by the Chartered Institution of Water and Environmental Management (CIWEM).

‘The reason being the Brits were truly to engineer everything out of the environment, so they could build anywhere. What the Americans realised was the landscape was on their side, they knew the environment and they knew how to work with it.

‘Major Gates formed the American Army Corps of Engineers to used the environment to their advantage.’

Reducing flood risk

The new report by the Environment Agency includes more than 60 case studies of natural flood management in the UK, along with data and evidence about how the idea can reduce flood risk.

Natural flood management is when natural processes are used to reduce the risk of flooding and coastal erosion.

Examples include: restoring bends in rivers, changing the way land is managed so soil can absorb more water and creating saltmarshes on the coast to absorb wave energy.

Mr Curtin said natural flood management is a ‘key way of improving climate resilience in this country’.

He also reflected on the floods and storms seen in the UK over the last five years. Mr Curtin said these included the summer floods of 2012 and the winter of 2013-14 which was one of the wettest in records.

‘The Thames barrier had to close 50 times that winter, which is a quarter of all the times it had to close in its 30 year history,’ he told the event. ‘In the whole of the 1980s it only had to close eight times’

‘Something seems to be changing,’ he added. ‘Maybe, our old traditional approaches need to change too. The key for me with flood risk is thinking our approach has to change quicker than the climate, or else we’re in trouble.

‘If you talk to the Dutch now about their future strategy, it’s about how they will using natural flood management and other processes to complement their engineering and buy their existing assets more time.’

Resilience relies on ‘mosaic’ of contributions

One of the case studies in the report looks at Hesketh on the Lancashire coast, where a ‘managed realignment’ scheme has created more than 300ha of saltmarsh, which protects 143 residential properties, three commercial buildings and 300ha of farmland.

According to the report, coastal schemes such as this, not only dissipate wave and tidal energy but can also reduce impact on defences, reduce tidal surges and lead to slightly lower water levels at defences.

The study includes a project in Debenham, Suffolk, where modelling has shown that installing a range of natural flood management features along the River Deben could provide more than 30,000 m3 of water storage – thereby reducing annual average damages to properties and farmland by 31%.

On Lustrum Beck, in Stockton-on-Tees, modelling showed that providing 100,000 m3 of storage in the upstream catchment, using wetlands, features to reduce run-off and river restoration, could reduce flows by more than 10%.

‘Good flood risk management is a like a mosaic,’ added Mr Curtin. ‘To get this country resilient we need a number of pieces to come together. No one organisation has all of the pieces in this mosaic, and that’s why it’s really important we come together.

‘Natural flood management is an important part of that mosaic when used alongside more traditional engineering. These projects also provide fantastic opportunities for community involvement and leadership,’ he added.

‘Many of our flood schemes already feature a mixture of hard and soft engineering and natural flood management. It can be a cost-effective and sustainable way to manage flood risk alongside traditional engineering, while creating habitat for wildlife and helping regenerate rural and urban areas through tourism.’

Photo by Reading Tom