BART has implemented nature-based solutions to deliver multiple benefits in the Winford Brook catchment.
As a result of a combination of desktop research and walkover investigations to ground-truth opportunities, BART has identified several locations where a suite of small-scale measures could contribute towards “slowing the flow” during rainfall events, reduce fine sediment and nutrient input to improve water quality of the Winford Brook which is currently failing Water Framework Directive status.
BART has identified several multi-benefit schemes throughout the Winford Brook via catchment wide investigations funded by Bristol Water during 2019/20. BART aims to raise the funds required to take initiatives forward.
During early summer 2020, BART delivered the first phase of the Watery Lane scheme, south of Winford, North Somerset. The scheme is situated within the headwaters of the catchment, where measures were designed to intercept surface water runoff and in doing so, temporarily store surface water to improve drainage of a road and delay the volume of surface water entering the Winford Brook downstream. The delivery of the scheme was funded by the Environment Agency.
Throughout the development and delivery phase of this project, BART worked closely with landowners to develop measures that would minimise disruption to land-use,which in this case is grazing. North Somerset Council installed two formal drainage grips to allow surface water to drain off the road, through a hedgerow and into a newly created attenuation pond. The water, is then stored within the pond, where suspended sediment is deposited. Once the water over-tops the pond, it flows through a flow calming scheme, where the flow pathway is intercepted by three bunded scrapes. The surface water slowly infiltrates through the final earth bund before flowing downstream into the watercourse.
Over time, as the attenuation pond and scrapes become a part of the landscape, they will vegetate and provide a seasonal habitat to local wildlife. BART will plant approximately 170 native trees throughout this scheme, which will increase roughness’ and which will further help to slow the flow as well as provide a greater and more diverse habitat corridor throughout the valley. Funding has been secured for tree planting from Bristol Water.
The scheme also included the movement of a gateway that becomes trampled by livestock during wet weather and was a source of sediment into the tributary of the Winford Brook, impacting water quality. As shown in the image below, a new gateway along with stone was installed to reduce soil erosion from livestock; a simple measure with widespread benefits.
The second part of the scheme, was delivered several hundred metres downstream of the measures described above, and builds upon the leaky dams installed by BART earlier in the year. Within the field adjacent to the watercourse that BART has installed four leaky dams, plans were agreed with the landowner to install a shallow scrape and in-field bund (as shown post construction in the image above). Over the course of the growing season, the bund will vegetate and intercept the overland flow pathways – this will intercept surface water from flowing onto a bridleway.
The combination of the measures introduced across this sub-catchment will improve floodplain connection, slow the flow of water during rainfall events, reduce sediment & nutrient inputs, sequester carbon and create new woodland habitat. Overall, the scheme will contribute towards improving the health of a failing watercourse.
For more information on the project and on BART’s wider work in the catchment please contact Simon Hunter: simon@bristolavonriverstrust.org
