The “Slowing the Flow” project at Pickering in North Yorkshire was designed to look at how changes in land use and land management can help to reduce flood risk through greater working with natural processes, as well as provide wider multiple benefits for local communities.

The project began in 2009 and succeeded by implementing a range of measures within the Pickering Beck catchment, including planting and restoring 18.5 hectares of riparian woodland, constructing approximately 130 large woody debris (LWD) dams, and installing more than130 heather bale check dams.

A number of Natural Flood Management (NFM) measures were also implemented in the adjacent River Seven catchment, including the planting 23 hectares of woodland and building 50 LWD dams. In addition, the catchment was the selected location for a novel trial of two timber bunds. These were constructed in August 2011 on Sutherland Beck, a tributary of the River Seven, to determine how these relatively cheap flood storage features would perform. The bunds span the full width of the floodplain at two central locations.

A family of Eurasian beavers (Castor fiber) was introduced to the Sutherland Beck catchment in a fenced enclosure in 2014 to see how they would interact with the established NFM measures and possibly replace these. Since their introduction, the number of beavers has grown, resulting in the formation of a number of large beaver-built dams and associated topographical changes.

A 2020 project carried out by Forest Research and repeated in 2023 involved an assessment of the integrity/strength of the man-made timber bunds, which concluded that both structures had degraded significantly and reaching the end of their effective life.

This publication reports the modelling work undertaken to estimate the potential flood storage provided by the beaver dams during design flood events, compared with that of the man-made timber bunds in their current condition, to determine whether the beaver dams offer comparable storage volumes such that the eventual loss/failure of the timber bunds does not pose an increased risk of downstream flooding.