A NEW scheme by the National Trust aims to return rivers to their natural path to reduce the impact of climate change, flood risk and to make space for nature, including the endangered water vole.
Allowing rivers to meander like ‘the branches of a tree’ rather than along a single channel will slow river flow, tackle the impacts of climate change by holding water in the landscape and improve habitat for wildlife.
The Stage 0 project on the Trust’s Holnicote Estate on Exmoor is the first of its kind in the UK and aims to reduce the frequency of flooding and re-connect rivers to their original floodplains. The scheme is inspired by successful river projects in America, including Fivemile-Bell in Oregon
Work has already started on a project to return a tributary of the River Aller on the edge of Exmoor to its original flow before human interference, allowing natural processes to be developed.
The hope is that this approach will lead to 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. If successful it will be developed over a 33 acre (13 hectare) site on the River Aller itself.
“With an increase in flooding and droughts predicted through climate change we need to make our landscapes more resilient to these challenges,” says the Trust’s project manager Ben Eardley. “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.”
The pilot project will use earth moving equipment to allow natural flow, sediment and biological processes to develop a fully-connected, stream-wetland system.
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 Trust over the past 12 months.
The Holnicote pilot is part of the National Trust’s £14 million Riverlands project, announced in August 2018, to improve seven river catchment schemes around England and Wales.
Pictured: Water vole at Holnicote, photograph by Steve Haywood; views of the Holnicote Estate, ©National Trust images/John Miller; project manager Ben Eardley sets up a time-lapse camera to monitor progress, ©National Trust images/Apex