Are beavers Britain's best water engineers?
The North York Moors National Park Authority published a report in October 2018 to highlight a proposed controlled release of beavers as part of a broader ‘slow the flow’ initiative to hold water back, higher up the Derwent catchment. This 16ha scheme will work in conjunction with other various natural flood management measures to alleviate the affects of flooding further down the catchment.
Sites in Scotland and Devon have also seen the reintroduction of Beavers, with a study in Devon showing promising results according to Professor Richard Brazier from Exeter University.
In 2011 a pair of beavers were released into an enclosed area of the Tamar headwater and following the success of this, 9 beavers making up two families were released at a new site on the River Otter in 2015. In 6 years the beavers created 13 ponds over a 183m stretch of stream at the Tamar site, which have captured 18 tonnes of carbon and 1 tonne of nitrogen so far.
Beavers dam watercourses to create pools in which they can move around, hide from predators and store food. The dams created by the beavers have also been found to have significant impacts on soil erosion, as they trap sediment from run off as well as the pollution that comes with it. This not only reduces soil erosion but ‘cleans’ the water too.
In terms of flood risk management the results are not as clear cut, initial evidence has shown that beavers help to reduce downstream flood risk but it will be some time before quantifiable results can be seen. Introducing beavers, along with other natural flood management measures is seen as a long term solution and ultimately the impact they will have does depend on where they decide to build their dams!
There are misconceptions that
- Re introducing beavers will impact negatively on fish numbers – beavers are strictly herbivorous.
- Beavers will flood valuable agricultural land, but it is possible to control the depth of the ponds which the beavers create by adding a ‘beaver deceiver’ which acts like an overflow device to maintain a specified depth.
Should beavers be given a seat at the table in future conversations about natural flood management and integrated land management? Although there is much more research needed it is important to acknowledge the potential role that beavers could play in flood risk management in the UK, however small.
Sources: BBC, Devon Wildlife Trust, The Guardian, North York Moors National Park Authority