Allowing rivers to meander like ‘the branches of a tree’ rather than along a single channel will slow river flow, increase wildlife and tackle the impacts of climate change by holding water in the landscape. It is the first scheme of its kind in the UK and aims to reduce the frequency of flooding, re-connect rivers to their original floodplains and increase wildlife by improving riverside habitat.
The project is being run in conjunction with Interreg 2 Seas Co-Adapt and the Environment Agency on the National Trust’s Holnicote Estate in Somerset. Work has already started on a pilot project to return a tributary of the River Aller on the edge of Exmoor to a more natural state.
The approach, known as ‘Stage 0’, will revert the tributary to its original flow before human interference, allowing natural processes to be developed.
The approach could develop a more resilient landscape better able to adapt to modern challenges like climate change and habitat loss. It also allows for more water to be stored in the water table to help in times of drought.
It works alongside nature to restore ecosystems and habitat diversity, providing a suitable home for species like the endangered water vole. Inspired by successful river projects in America, including Fivemile-Bell in Oregon, it is the first time such a technique has been tried in the UK.
The initial project will involve 10 acres of land involving a tributary of the Aller river, but, if successful, will then be developed over a 33-acre site on the River Aller itself.
Ben Eardley, project manager for the National Trust said, “Many streams and rivers have become disconnected from the surrounding landscape through years of land drainage and mechanised flood control.
“Conventional river restoration projects typically ‘re-meander’ straightened streams, working on the assumption that these streams were single channelled before human interference. But there is strong evidence that prior to disturbance many watercourses naturally flowed through multiple branching channels, a bit like the branches of a tree.
“Over hundreds of years we have simplified and concentrated rivers into a single, straight channel that has over time become disconnected from the land around it. Instead of storing water and depositing sediment, and recharging groundwater aquifers, these modified systems move water and sediment rapidly through the catchment, providing no buffer against floods, droughts or valuable top soil loss.
“With an increase in flooding and droughts predicted through climate change we need to make our landscapes more resilient to these challenges”
The pilot project will use earth moving equipment to allow natural flow, sediment and biological processes to develop a fully connected, stream-wetland system. After this work is complete, habitat restoration will be ‘fast-tracked’ by using woody debris and key plant species to help develop more hydrological and ecological diversity on the site. The resulting habitat will benefit a host of plant and animal species, including the 300 water voles released by the conversation charity over the past 12 months.
Mark Harold, Director of Land and Nature at the National Trust, added, “To make a real difference we need to be bold – to work beyond our boundaries and involve our neighbours; working with farmers and other partner stakeholders and engaging with local communities to deliver our vision for a healthy and beautiful natural environment.”
The project is also part of the conservation charity’s Riverlands project announced in August 2018, where over £14 million will be spent on seven river catchment schemes around England and Wales.