A pioneering river restoration project on the National Trust’s Holnicote Estate in Somerset has delivered dramatic benefits for both wildlife and local communities in just 12 months.
The project, which used the innovative 'Stage 0' approach, has reconnected the River Aller to its floodplain, transforming the landscape into a thriving mosaic of wetlands, says the conservation charity. The approach, the first of its kind in the UK, was adapted from methods first developed in Oregon, USA.
Over 10 football pitches’ worth of new wetlands have been created, leading to a remarkable 1,800% increase in aquatic habitat. The restored floodplain now plays a key role in slowing water flow, improving water quality and reducing flood risk for downstream communities.
The project has turned what was once a neat, sterile landscape into a dynamic 'messy' ecosystem, teeming with life. Species such as water voles, wildfowl and even green sandpipers are thriving in the new habitat, alongside an array of birds, insects and plants.
What is Stage 0 restoration?
The National Trust describes Stage 0 (or Stage Zero) restoration as the ‘ctrl alt delete’ of a river – in essence, a 'reset'.
Inspired by successful river restoration efforts in the USA, such as Oregon's Fivemile-Bell Creeks, this project marks the first time the Stage 0 technique has been used on such a large scale in the UK.
The US Stage 0 restoration sites have shown incredible resilience, withstanding the impacts of wildfires, extreme heat and prolonged drought, while providing vital refuges for wildlife during challenging conditions. This innovative method has the power to reverse centuries of drainage, transforming landscapes into thriving, nature-rich habitats that benefit both wildlife and local communities.
At Holnicote, the Stage 0 project involved filling in a 1.2km managed, straightened and deepened section of the River Aller to fully reconnect its waters with the surrounding floodplain.
“Trying any new technique is of course challenging but we need to be bold in order to tackle the climate and nature crisis," says Ben Eardley, project manager at the National Trust.
After being tested during England’s wettest 18-month period on record, the restored landscape not only withstood the extreme weather but helped prevent floods and droughts by storing and releasing water naturally.
“We had just the worst winter you can imagine post restoration in terms of the number of storms and sheer volume of rain," says Eardley. "The site responded really well... demonstrating the value of the restoration in providing resilience to hydrological extremes.”
Flood defence
Using drones and in-river sensors, scientists from Exeter, Loughborough and Nottingham universities have been tracking changes to the site's water flow and habitat quality. Their findings show the project is not only benefiting wildlife but also reducing flood peaks downstream by up to 38%.
Dr. Richard Mason from Sweden's Umeå University explains how the floodplain has essentially become a giant sponge. "Ground water levels rose dramatically across the site, in some places by over a metre. This allows the site to act as a large sponge or filter in the river catchment, helping to store winter flood water, reducing flood risk downstream and releasing cleaner water more slowly in the drier months to help alleviate drought conditions.
"The twists and turns and numerous flow paths that are now present in the floodplain as the water wends its way over the site through thick vegetation, act as a filter to capture sediment eroded from upstream."
Wildlife wetlands
Mason explains how “the development of habitat to include faster flowing riffles and gravel beds has also been key for benefitting fish and other aquatic species. The site has moved from a very simple, static system with little opportunity for wildlife to one with significant dynamic complexity, which has seen an explosion in life," he says.
“Put simply, the system has moved from a very tidy area with little for wildlife to a messy complex jumble of waterscapes and diverse habitats that is full to the brim with a huge variety of plants and animals.”
Holnicote Estate ranger Jack Siviter echoed these sentiments: “The site has gone bananas in terms of the amount of wildlife and lush vegetation growth that we’ve seen," says Siviter.
“There is a huge variety of plants and trees starting to shoot up across the wetlands, such as greater tussock sedge, which can grow to over two metres tall. This will provide a rich landscape for wildlife to thrive within.
“Thanks to the increased wetted area we’ve seen loads of water-loving creatures, like wild waterfowl, water voles, eels, lamprey, grass snake, trout and birds such as red kite, buzzard, kestrel, sparrow hawk, swallow, swift and sand martin.
“The martins, swifts and swallows are all using the site for feeding and nest building, while the birds of prey are using the site for foraging – which is in part due to the rewetting but also the longer sward.
“The constant supply of water has also resulted in the site being very green and lush with thousands of wildflowers, like wild carrot, providing food for pollinators.
“As a consequence, we’ve seen raptors such as kestrels, herons and deer and even barn owls.”
Siviter says the site has seen such an increase in insect life that at times "there have been so many swallows the effect has been a feeding frenzy with hundreds and hundreds of birds swarming to feed on the abundance of food.
“One of the coolest species we’ve seen is a green sandpiper – which is a great indicator species for healthy, lowland wetland habitat,” Siviter adds.
Vole refuge
The team are keeping a particularly close eye on water voles, a species indicative of a healthy wetland habitat.
Hazel Reading, an ecologist who has been working on the site, explains how “the restoration area started as a linear ditch with patches of suitable water vole habitat along it. This patchiness can limit the voles’ ability to migrate and find the best seasonal food, or even each other, without risking predation.
“The new habitat is expansive, connected, and has started growing up wonderfully. With an abundance of their favourite food plants and a link to the surrounding water vole populations, they’ve ended up with a little slice of vole heaven," she adds.
“Although 12 months in we can only really say it’s a foothold for now, I wouldn’t be surprised to see a big increase in their population in coming years!”
What's next?
This river restoration is part of a wider effort to reconnect UK rivers with their natural floodplains, offering a model for future projects aimed at increasing climate resilience while providing rich habitats for nature.
As the project continues to develop, it promises to serve as a trailblazing example of how working with natural processes can deliver immense benefits for both nature and people.
Main image: Deadwood at the Stage 0 site is a valuable habitat for insects, while the greater tussock sedge growing in between is an important refuge for species such as water voles/National Trust Images (James Beck)
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