From the summer of 2019 to the spring of 2020, Britain experienced catastrophic floods. In August 2019, the dam at Toddbrook Reservoir was so badly damaged that the town of Whaley Bridge had to be evacuated. February 2020 was England’s wettest ever, with floods in towns such as Hebden Bridge during Storms Ciara and Dennis. And these have become far from unusual events. In its National Flood and Coastal Erosion Risk Management Strategy for England, published in July this year, the Environment Agency has recognised that by 2050, there could be up to 59% more precipitation in winters due to climate change.
As well as setting in motion flood warning systems, like those highlighted in the Environment Agency’s Flood Action Campaign (running from 9 to 15 November), the Strategy talks about the importance of nature-based solutions to store flood waters on high ground. Peak District-based Moors for the Future Partnership is working with the Environment Agency to deliver natural flood management techniques across catchments in Greater Manchester, Cheshire and Merseyside (GMMC).
The Partnership has been working in the Stalybridge catchment constructing 200 mini-dams, made from stone, peat and timber. These dams are designed to slow the flow of water, holding it on the moor, but are deliberately leaky, allowing water reach the valleys in a controlled way, thus lowering the chance of floods occurring downstream.
Peter Costello, Area Flood and Coastal Risk Manager with the Environment Agency said: “Well-maintained peatlands are an iconic aspect of the English landscape and are a vital part of the natural ecosystem. They provide key habitats for wildlife, reduce carbon emissions and can help slow the flow of water. This project demonstrates that there are natural ways of reducing flooding beyond traditional hard engineering solutions. The more of these schemes we have, the more we can use our natural habitats to help us build climate resilient places, which is a key objective of the Environment Agency’s long-term flood and coastal erosion risk management strategy.”
Bare peat, found on the moors of the Peak District and South Pennines, has been degraded by centuries of industrial pollution and wildfires, allowing rainfall to run off, with no surface roughness to slow the flow. Over the last 17 years, Moors for the Future Partnership has installed over 31,000 mini-dams, to slow water run-off from grips and gullies on moorland. The Partnership plants sphagnum moss and other moorland plants to stabilise bare peat and create surface roughness. These techniques slow the flow of water from the moors, reducing peak discharges by around 30% and increasing lag times (the time it takes rain water to reach a river) by up to 20 minutes.
This practical restoration work is supported by monitoring work from the University of Manchester, as part of the £1.2 million Natural Environment Research Council-funded Protect-NFM project. This work checks how effective the conservation work is in providing a low-cost way to reduce the risk of flooding in vulnerable rural communities. The science and monitoring officers are conducting a series of experiments to assess the potential impact of various forms of gully blocking, restoration of sphagnum cover on moorlands, and establishment of upland woodlands on run-off from moorland. The data will then be used to develop user-friendly computer simulations which will predict the best combinations of interventions for different flooding scenarios, which will be shared with conservationists to influence restoration techniques in the future.
With climate change leading to increased extreme weather, natural solutions are required to stop floods before they begin and the Environment Agency, as part of Moors for the Future Partnership, continues to search for new ways to slow the flow.