Slowing the Flow
Last winter, when it was sheeting down again in north west Sheffield, the villagers of High Bradfield were cheerfully going about their business, one of them in shorts, as if monsoon-style rainfall was commonplace. And nowadays, of course, it is.
“We’ve just had the wettest February on record,” said the dripping Nabil Abbas of Sheffield and Rotherham Wildlife Trust. “And last year was the wettest autumn since records began in the 1880s.”
One of Nabil’s jobs is to try and do something about all this rain. The phrase, he says, is ‘Slowing the Flow’.
“Sheffield is effectively in a bowl with hills all around it,” he said. “So we need to be forward thinking about how we manage water.”
The initiative, within the higher catchment of the River Don, covers the Loxley, the Rivelin, the upper Don itself and the springs that trickle or gush down the slopes of the Dark Peak.
Professionals working with water use terms like ‘1 in 100’ or ‘1 in 200’ annual probability of flooding, explained Roger Nowell, who works on flood management for Sheffield Council.
“But a 1 in 100 risk ten years ago is different to 1 in 100 now,” he said. Sheffield will need to build flood defences as part of a mix of interventions to cope with flood risk in a changing climate, he said.
“But Natural Flood Management is definitely going to be part of our flood defences, to store more water in the countryside,” he said. “Keeping the water out of the city in the first place.”
Working effectively with the water cascading down onto the hills of Sheffield’s Lakeland means working with the local people too, said Nabil, including large landowners like Sheffield Council and Yorkshire Water, local families, and the dozens of Lakeland farmers, many of whom have worked the hills of the Bradfield parish for generations.
“The weather is definitely more extreme,” said Richard Hague, whose family have farmed at High Bradfield since 1948. “When it rains it goes on for days and days, and if you get a drought it goes on for ages too.” He thinks big changes are coming for farmers, with high intensity farming becoming a thing of the past.
“I think the more you can do to work with the environment, on waterways, on the land with nutrients and fertilisers, I think the better off you’ll be as a farmer.”
Natural Flood Management measures are often very cost effective, says Nabil. Many local farmers have relatively few livestock and still have areas of scrub and trees on their land. More traditional farmland like this, which is still seen right across the Bradfield parish, helps retain water better than heavily grazed hillsides or ploughed fields.
It’s also very useful for storing carbon, said Anthony Downing from the Environment Agency.
“Very old pastureland has lots of worms and invertebrates that pull vegetation down to lock carbon into the soil,” he explained, “and in the long term, that sort of healthy soil is good for the productivty of the land in a sustainable way. It’s a natural process.”
And working with landowners to build simple ‘leaky dams’ and allowing wood to fall into streams, or allowing a new pond to form in swampy field corners all help slow the flow, keep water on the land, and improve biodiversity.
Fencing off some ponds and watercourses, and providing livestock with troughs can improve water quality and encourage wildlife like frogs and dragonflies, while also keeping livestock out of dangerous bogs.
There’ll be plenty of tree planting too, but the right trees in the right places said Nabil. “Some people seem to think that tree planting can save the world, but actually per hectare, wetlands often hold more carbon.”
Battling the elements with Nabil was Jonathan Bridge of Sheffield Hallam University, whose team is monitoring how successfully the array of leaky dams, ponds, scrublands and fenced watercourses slow the flow over the next few years.
“Every bit of landscape is connected to a river somewhere,” said Jonathan. “By modelling and mapping, we hope to understand how water behaves. We want to know the characteristics of the catchment.”
Scientists like him use the word ‘flashy’ to describe areas where rain falls and runs off the land quickly, sometimes when fields are more closely cropped, better drained and there are fewer trees. He cites the top of the Porter and Sheaf catchments above Sheffield as being ‘flashy.’
“Having more vegetation around a river, or planting more trees, can help to provide what we call ‘roughness,’” he said.
All of which helps slow the flow and store more water in the uplands. The question in ‘flashy’ areas, he says, is how can we get that storage back?
He and Anthony Downing of the Environment Agency are confident there’ll be valuable data from the probes hidden in the Lakeland’s streams.
“What we learn here will be used all over the country,” said Anthony.
A short video about the groundbreaking work in Sheffield Lakeland by local filmmakers Picture Story Productions explains the work to the local public.
“A big part of the project is to make the rest of Sheffield realise the value of this land,” said Nabil and the value of the people who work it.”