Can beavers have an impact on reducing flood risk?
Beavers were hunted to extinction over 300 years ago for their pelts however they have made a comeback over the last couple of years after being reintroduced to several areas of the UK due to the multiple environmental benefits that they provide.
Sites in Scotland and Devon have seen the reintroduction of Beavers, with the most recent study in Devon showing promising preliminary results according to Professor Richard Brazier from Exeter University who runs the trial.
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. Since then it seems that the beavers have been busy, with Brazier saying that the unpublished preliminary results show that the beavers are having multiple positive impacts on the catchment.
In 6 years the beavers have 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.
The dams created by the beavers have also been found to have significant impacts on soil erosion at the site, as the dams have been trapping sediment as well as the pollution that comes with it, which is usually lost when there is heavy rainfall causing sediment to be carried downstream in run off. This not only reduces soil erosion but ‘cleans’ the water too.
The benefits for habitat creation and biodiversity are also promising, with the pools created by beavers released as part of a study in Ayrgll in Scotland showing 20 times more aquatic plant life and a 28% increase in the number of species in the surrounding habitat.
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 by building ‘leaky’ dams which slow down the flow of water and hold more water upstream on the floodplain. It will be some time before we see quantifiable results on the impact that beavers have on flood risk as natural flood management measures are long term solutions and ultimately the impact they will have does depend on where they decide to build their dams!
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.