Work implementing a series of natural flood management measures in the Limb Brook Catchment to help protect Sheffield and the region against future flooding continues on new sites, this time regenerating a popular urban site at Whirlow Playing Fields to provide flood water storage and improve the area for wildlife.
The Limb Brook Nature Based solutions (NBs) Demonstrator project is a partnership between the Environment Agency, Sheffield City Council and Sheffield & Rotherham Wildlife Trust.
As part of the Upper Don Source to Sea programme, the works use a number of natural flood management methods used to help store and slow water flows, to reduce the risk of flooding at at-risk locations downstream in the Don, as well as supporting wildlife.
Features like the sports pitches on Whirlow Fields, are usually artificially drained with the rapid run-off of water passed to nearby watercourses (here, the Limb Brook, a tributary of the Sheaf, in turn a tributary of the River Don). In periods of high rainfall, this can add to existing high flows which can cause flooding downstream.
Nowadays proposals for new pitches are required to slow the flow – this project has sought to do this retrospectively by breaking into drainage systems and bringing the flow to the surface as streams – in effect, discovering new watercourses – and directing it into a series of six attenuation ponds (which hold and slowly release excess water) and swales (shallow, grassy channels which slow and direct the flow of water, essentially little streams).
This more natural drainage causes slower movement of rainwater once it hits the ground, as it moves through long vegetation and snakes around bends. In addition, the ponds act to temporarily hold off water during storm events. Bringing water to the surface and out of its pipes can create a new dynamic and biodiverse landscape. These features along with wildflower, meadow and hedge planting will also support a range of wildlife including birds, insects and amphibians, as well as creating resilience to the climate and ecological emergencies.
A local solution
Dr Kevin Spence from Sheffield Hallam University undertook engineering design of the flood storage reservoirs and attenuation ponds for various storm events, while Professor Ian Rotherham was involved with ecological and landscape history assessments. The changes in water movement are being monitored onsite via a large citizen science component involving the local community, and in the river with specialist hydrology equipment.
Even in these early stages, with not all ponds yet in place and some bare areas where vegetation has not yet fully colonised, the scheme is already working. Water is flowing through the swales constantly; and during a recent extreme rainfall event, the ponds held a significant amount of water, slowly releasing it into the swale systems, which directed the flow into the bund at the bottom of the field where it dissipated into the woodland. Ongoing works have seen similar interventions along the course of the Limb Brook and its catchment area; from Lady Canning’s Plantation down through the Limb Valley to Ecclesall Woods.
Leo Ingvorsen, Nature Recovery Manager (Water) at Sheffield & Rotherham Wildlife Trust said: “With all the dry weather recently it is hard to think about heavy rain, however, we know we are more likely to face extreme weather. This work on Whirlow allows us to capture more water during extremes whilst holding some water for wildlife makes the site, and city, more resilient against flooding, and resilient for wildlife. Due to the pond control design we can choose if we want to capture water for a common flood event like annual heavy rainfall, or a severe event which may only happen once every 30 years. It’s a clever way to future proof Rotherham, Sheffield and other communities downstream, while providing a wildlife-rich landscape for everyone to enjoy.”
Anthony Downing, Catchment Coordinator, Environment Programme, at the Environment Agency said: “These ponds and swales to slow the flow of rainwater from the Whirlow Playing Fields deliver another key element of the Limb Brook pilot project. The ponds constructed this spring in Lady Canning Plantation are already working well, later more leaky dams and other measures will be installed along the Limb Brook. Delivering varied interventions along the whole of a watercourse as well as slowing the flow also provides a chain of water dependent habitats to improve biodiversity, and the knowledge we gain from this project will inform how the Source to Sea programme will deliver Nature Based Solutions across the River Don catchment.”
Cllr Mazher Iqbal, Co-Chair of the Transport, Regeneration and Climate Policy Committee, said: “This project demonstrates why partnership working is so important, together we’re protecting our communities and supporting our natural environment. It’s great to see innovative schemes like Whirlow Playing Fields delivering essential benefits, in this case returning part of River Sheaf catchment to a more natural state where the landscape slows the flow and providing a newly formed habitat for wildlife.”
How to get involved
Sheffield & Rotherham Wildlife Trust are looking for volunteers to help with some of the practical tasks, such as tree planting. We will also welcome the support of regular visitors and neighbours in gathering data, which Sheffield Hallam University will use to help determine the success of the work carried out. The Trust are looking for citizen scientists to help gather rain gauge data and carry out fixed point photography. If you would like to help please email firstname.lastname@example.org.