New 'leaky dams' are being hailed as a game-changer on Greater Manchester's moors, where they're not only reducing the risk of devastating wildfires but also helping to prevent flooding in valleys below. The innovative structures, built by The National Trust and United Utilities, have been strategically placed across Holcombe Moor.
These wooden dams retain rainwater on the peatlands, elevating groundwater levels – a vital process known as re-wetting. It's particularly crucial during hot spells, as it helps create natural fire-breaks, significantly reducing the risk of moorland blazes. Nik Taylor, National Trust Ranger for Holcombe Moor, stresses the importance of keeping the moors wet to prevent fires and restore peatlands.
The leaky dams also play a key role in natural flood management by slowing water flow into the River Irwell catchment area, preventing rapid surges that can overwhelm downstream communities. This approach gained traction after the 2015 Boxing Day floods, which saw over 2,200 properties affected when the River Irwell burst its banks following Storm Eva.
The project involves planting sphagnum moss, a highly absorbent wetland plant capable of holding up to 20 times its own weight in water. This helps form peat bogs that lock vast quantities of carbon into the ground, while re-wetting sustains and restores habitats for endangered wading birds such as Dunlin, Golden Plover, and Lapwing.
United Utilities highlights the benefits of utilising moors as a 'natural sponge', stating that retaining water on uplands can reduce combined sewer system volumes. This improves the environment by mitigating storm overflows and preventing untreated wastewater from spilling into rivers during heavy rainfall.