Kent leaky dams commended by Environment Agency
The Hadlow Estate’s natural flood management scheme (NFM) has been visited by the Environment Agency to showcase the project to national experts and highlight the practical challenges of delivering NFM.
61 ‘leaky dams’ are designed to slow the flow of water in woodland streams on the Estate. The dams were installed at the Pembury Walks Woodland, part of the 900-acre Tudeley Woods nature reserve, with the help of the South East Rivers Trust (SERT) and the Environment Agency from 2019-2021.
The Environment Agency’s (EA) chief scientist, Dr Robert Bradburne (pictured below, centre) visited the Estate with colleagues Tom Cook, a biodiversity technical specialist, David Webb, biodiversity team leader, and Julie Foley, the EA’s director for flood risk strategy, primarily to examine the impact of leaky dams on reducing flood risk downstream on the river Medway. SERT were also present to explain how construction and monitoring took place.
Robert said: “It is great for me to understand the complexities of implementing and evaluating these novel approaches on the ground. I was thoroughly inspired by the wide range of co-benefits being delivered in the schemes and the passion of the people working to deliver them”.
Tom Cook said: “Hadlow was chosen because the EA wanted to see how natural flood management can work in practice, help improve our understanding of the multiple benefits, and make a difference to people living downstream.”
The leaky dams are designed to hold and slow the flow of water, reducing the flood peak downstream. Holding water back also creates a wetter woodland habitat and long term monitoring will be needed to gauge the effect this is having on the biodiversity in the area. The NFM measures are altering the stream bed and sediment deposition, and this will be monitored again in the future to see how they develop.
“It is remarkable to see how the leaky dams have restored the soil’s capacity to hold water, and renew the wetland communities,” added David Webb. “This will not only improve the ecology of the woods, but also improve the resilience of those communities to both drought and flood.”
The scientists visiting the project have been hosted by Kate Teacher from the Estate, who said it had been extremely valuable to welcome the EA’s chief scientist along with ecologists, geomorphologists, and other experts onto the site to get their views on the wider benefits of Natural Flood Management for the environment.
“There are a lot of potential benefits from these dams – it’s not just about reducing the flood risk, it’s about what they bring to the area in terms of biodiversity gain and improving the environment too,” she said.
“We are proud to see the work here recognised by national experts. For the dams at Tudeley to be chosen for field trips demonstrates their success and future potential.”
The dams, constructed from fallen timber or the trunks of over-mature conifers that needed felling, are all in perfect condition still, suggesting they will continue to reduce flood risk to properties downstream, although there is still scope to do more on the Alder Stream catchment if further funding becomes available.
The steep sided streams, or ghylls, have logs jammed across them in a variety of designs, using only natural materials. Over time more sticks and debris gather behind the dams, slowing the flow of water further.
Read the full Medway Natural Flood Management report here.
