BART have been working with landowners upstream of Malmesbury to identify opportunities to develop and implement Natural Flood Management (NFM) opportunities across their landholdings. NFM is a process in which we work with nature to store water in the upper reaches of a catchment to help reduce flood risk downstream, increase the resilience of the landscape whilst providing additional habitat. Malmesbury, a town positioned alongside the upper reaches of the Bristol Avon, has been experiencing increasing frequency and severity of flooding in recent years and NFM was proposed as a key measure for helping reduce the risk of this into the future.
During 2024 BART produced opportunity reports for several farms in the region identifying a multitude of measures ranging from hedge creation, leaky dams, buffer strips and floodplain reconnection. All of these measures play a role in helping to slow the flow of water across the landscape, store water outside of the river channel and also provide varied and diverse habitats in the process.
A detailed design of the NFM works at this farm was put together and the ground works recently closed out in May 2025. In total 8 large floodplain scrapes and 12 large woody debris features were created adjacent to two ephemeral streams. These features will work to reconnect the floodplain, holding water back during elevated flow conditions and slowing the flow downstream. The scrapes are up to 25m long and 10m wide reaching to a maximum depth of 1m. The average depth of the scrapes was kept to 0.5m to increase the amount of shallow marginal habitat available when they are wet. These gently sloping shallow margins provide habitat for a range of wetland species and we are excited to see what will turn up as the site beds in and develops.
A low earth bund was created at the downstream end of each scrape to help further retain water in the structures and also provide additional habitat variability in the previously flat grass field. The scrapes are being seeded with a local wetland seed mix and some topsoil sprinkled over to help the colonisation of the existing seed bank back into these areas. Once vegetation has returned to the scrapes, the field can continue to be grazed by livestock meaning the landowner hasn’t lost any pasture, local habitats are diversified and downstream communities should face a lessened flood risk. A fantastic win-win-win.
Whole tree limbs were selectively coppiced from certain trees in nearby hedgerows to be fixed in place into the channel. Leaky dams partially block up a watercourse to help spill water outside of the channel onto the floodplain but allow some baseflow through. Using whole tree limbs helps mimic natural tree fall and will have the additional benefit of providing scratching posts for the resident cattle. It is estimated that around 1000 m3 of water will be stored in the scrapes in addition to that held up behind the large woody debris structures.
Reconnecting rivers with their floodplains in this way helps create dynamic and complex water systems in which there are a variety of wet habitats and areas with differing amounts of water held there at different times of the year. This abundance of habitat diversity provides the opportunity for the increase in biodiversity in the local area. This highlights the importance of NFM as a tool kit, through these actions we can restore our rivers and riverside habitats while having the additional benefit of reducing the flood risk to downstream communities.
Through this project BART aimed to further engage local landowners by running an interactive NFM Workshop with members of the South Cotswolds Farm Cluster. This event involved a lecture, training and discussion on NFM and methods of working with nature across productive farm environments to help reduce downstream flood risks. In addition to this work, we are looking into funding opportunities to deliver further work scoped out during this project.
BART would like to thank the Environment Agency for funding this work and the landowners for their enthusiasm and willingness to trial out NFM measures on their land.
