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Leaky dams to prevent moorland fires and flooding

Richard SteadNorth West
BBC Photograph of volunteers installing leaky dams on Holcombe Moor. The image shows wooden posts being hammered into a gulley on the hillside.BBC
The leaky dams were created by hammering wooden posts into a gulley on the moors above Ramsbottom.

A series of 'leaky dams' have been created on the moors surrounding Greater Manchester to stop wildfires from spreading and to prevent flooding in the valleys below.

The wooden dams have been installed in gullies by The National Trust and United Utilities across Holcombe Moor, part of the Stubbins Estate above Ramsbottom.

Nik Taylor, 57, a National Trust Ranger for Holcombe Moor and the Stubbins Estate, said: "Keeping the moors wet by raising ground water levels is really important when we're in a period of hot weather because it can help create fire-breaks."

United Utilities said using the peat land as "a natural sponge" can keep water on the moors giving multiple benefits.

Photograph of the National Trust ranger Nick Taylor. He is pictured in front of wetland reeds on Holcombe Moor.
Nick Taylor is a National Trust Ranger for Holcombe Moor and the Stubbins estate.

Taylor said: "We use leaky dams to control the flow of water into the River Irwell and it's an essential part of the restoration of our peat lands.

More than 1,000 acres of land at Holcombe Moor was transferred from the Ministry of Defence to the National Trust in 1994.

The dams are designed to hold back the flow of rainwater which lands on the moors and subsequently enters the River Irwell catchment area.

The work also involved planting sphagnum moss - a spongy wetland plant which is capable of holding up to 20 times its own weight in water.

The sphagnum helps to create peat bogs, where dead vegetation accumulates rather than decays, capturing vast quantities of carbon in the ground.

Photograph of Freya Bowden who is a masters student at the University of Manchester. She is pictured on Holcombe Moor above Ramsbottom.
Freya Bowden is a Master's student studying moorland management at the University of Manchester

The leaky dams are built using wooden posts in gullies on the hillside, leading to a rise in the water table, which help to reduce the risk of moorland fires.

The dams can also be made using stone, heather or peat.

The re-wetting of the moors by creating the dams also helps to preserve habitats for wading birds such as the Dunlin, the Golden Plover and the Lapwing.

Freya Bowden, a Master's student who is studying moorland management at the University of Manchester, said: "The dams slow down the water, so it doesn't reach the catchment areas downstream as quickly and that can prevent flooding."

"The recent wildfires have been awful but by re-wetting the peat lands we are improving bio-diversity and helping to mitigate the spread of the flames", added the 22 year-old.

Photograph of volunteers installing leaky dams on Holcombe Moor. The image shows two people creating a wooden frame inside a gulley on the hillside.
Leaky dams have been created on the Stubbins estate to help keep the moorland wet and prevent wildfires from spreading.

Natural flood management measures have become increasingly widespread since the Boxing Day floods which affected large parts of Greater Manchester in 2015.

More than 2200 properties in the area experienced flooding when the River Irwell and its tributaries burst their banks after unprecedented rainfall from Storm Eva.

The worst-affected areas included Rochdale town centre, Ramsbottom, Bury, Radcliffe and Lower Broughton in Salford.

Johnny Phillips, a business development manager for rainwater management at United Utilities, said: "By using the moors as a natural sponge, we can keep the water on the moors for as long as possible and that has multiple benefits."

"The leaky dams can also reduce the amount of water that gets into our combined sewer systems and that helps to improve the environment by preventing storm overflows from spilling."

Photograph of Johnny Phillips from United Utilities. He is pictured on the moors above Ramsbottom, with a herd of cows in the background.
Johnny Phillips works in rainwater management at United Utilities.

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