Beavers can play a role in tackling flooding, a new assessment from the Environment Agency on how nature can help address floods has said.
The updated directory summarises the latest evidence for the flood and coastal erosion benefits of 17 natural measures from river restoration to woodlands in catchments and along water courses.
It can also manage saltmarshes and sand dunes.
The Environment Agency said it was “mainstreaming’’ the use of natural flood management alongside the use of traditional engineered defences, with £25 million ($31 million) programme.
It said this is part of the £2.65 billion two-year flood defences package recently announced by the UK government.
The directory would help inform investment decisions and support the selection of measures on the ground, the agency said.
For the first time, the directory draws on research, including more than 700 scientific papers.
It included an assessment of the role beavers, oyster reefs, and underwater seagrass and kelp can play in protecting against floods and coastal erosion.
It finds the presence of beavers, which engineer the ecosystem by building dams and channels which can reduce peak flows.
It also reduces the speed of water flows, increases groundwater storage, traps sediment, connects up floodplains, as well as supports other wildlife and stores carbon.
But it said more evidence was needed, particularly from the UK, in a range of areas such as the number and location of dams in catchments.
Catchments that were needed to have significant flood reduction benefits downstream, and understanding the most effective management and maintenance techniques.
Beavers were hunted to extinction in Britain around 400 years ago, but have made their way back to England’s rivers, through escapes from enclosures and illegal releases, and were given legal protection in 2022.
But conservationists are keen to re-introduce beavers, to create wetlands and river systems that boost an array of other wildlife and militate against drought and floods.
They were still waiting on a government decision about licensing wild releases of the semi-aquatic mammals.
The directory from the Environment Agency also highlighted the use of schemes such as tree planting, showing the value of woodlands across a water catchment.
It reduces the flood risk as well as provides benefits for soil, wildlife and water quality.
Catchment woodlands can reduce the height of flood water, particularly during smaller events with one study in Cumbria suggesting the flow of water was slowed by 14 per cent to 50 per cent compared to pastureland.
The directory highlighted how restoring saltmarsh and mudflats protects coastal areas from storms but also has wider benefits, such as storing carbon and filtering sediments and nutrients.
A managed realignment scheme, where old sea walls were breached to enable the creation of 250 hectares of saltmarsh at Steart Marshes in Somerset, is storing 36.6 tonnes of carbon per hectare.
A recent study found, which compares favourably to woodland.
The directory points to research gaps, for example, the best depth of a reef to help oysters grow at the same time as reducing wave energy, and the best methods for developing such reefs.
Julie Foley, Environment Agency director of flood risk strategy and national adaptation, said.
“With climate change increasing the threats of flooding and coastal erosion, we must work together with nature to boost resilience across the country.
“That’s why the Environment Agency is mainstreaming the use of natural flood management alongside the use of traditional engineered defences.’’
She said the £25 million natural flood management programme was shaped by the “working with natural processes evidence directory.’’
She said the fund was testing approaches to future investment and the delivery of natural flood management.
Kathryn Brown, The Wildlife Trusts director of climate change and evidence, said: “Getting the best evidence to support our collective efforts to build resilience is critically important.
“I’m delighted to see the latest science on natural flood management coming together in one place through the Environment Agency’s evidence directory.
“With a focus on co-benefits and to see new recognition of the role beavers can play in natural flood management.’’