Kinder's dipwell volunteers - Moorland restoration to help prevent flooding
PUBLISHED: 00:00 04 February 2020
Once a year Moors for the Future takes stock and monitors the depth of the water table on their restored moorland. Andrew Griffiths joins them to learn how their work on the hills can help prevent flooding in our towns and cities.
Flooding is in the news again. Sheffield's rivers burst their banks and left people stranded at the Meadowhall shopping complex, and devastated people's homes in the South Yorkshire village of Fishlake, near Doncaster. Closer to home the River Derwent became a torrent and tragically took the life of former High Sheriff Annie Hall, also causing flooding in Matlock and Belper. Further autumn flooding affected people's homes, land and lives throughout Yorkshire and the Midlands.
Whenever such high profile flooding hits the news, the predictable baying for more active river management begins - 'dredge the river', 'straighten the rivers', 'build walls', 'get the water out to sea as quickly as possible'.
But unfortunately, experience over decades has shown us that such tactics just do not work - if anything they tend to make things worse. Move the water quickly, yes, but that means that more tends to reach 'bottlenecks' all at the same time, and those bottlenecks are often where rivers flow through towns and cities, where people live and form communities and where the floods can do the most damage and cause the most misery.
More recent experience is teaching us that a more effective tool in our flood defence armoury is to slow down the rate at which water enters our rivers and makes its way through the river system. This can be achieved by using techniques known as Natural Flood Management (NFM), the collective aim being to 'slow the flow'. It is a different way of thinking about how we manage our water.
It is an obvious point, but floods happen when a lot of rain falls all at once. So if we are going to manage that water better, then the place where most of it falls is a good place to start: and that is up on the top of the moors. Seventy per cent of our drinking water, for instance, comes from these hills.
One problem has been that much of our moorland, which should be a rich tapestry of plants, trees, shrubs and bog land, has been degraded by successive decades of industrial pollution and poor management to bare peat.
That famous walker and writer of hillwalking guides Alfred Wainwright once wrote of Black Hill, near Crowden: 'No other shows such a desolate and hopeless quagmire to the sky, this is peat naked and unashamed.'
This is not only ugly to the eye, but the rain just runs straight off it and down into our rivers and, all too often given the increasing occurrence of the severe storms that climate change is bringing in its wake, straight into our front rooms.
For almost 20 years the Moors for the Future Partnership has been working to restore the vegetation to these moors, and re-establish the all-important bog-forming plant, Sphagnum moss. The aim is to raise the water table and once a year, during the autumn months, Moors for the Future staff and volunteers go out to check on the progress of their work. They do this by monitoring where that water table is: think of it as a kind of stocktaking or audit to check that the work they are doing is having the desired effect. This is the 'dipwell' season, and these are the 'dipwell volunteers'.
One late October morning I set off from the Snake Pass and followed the Fairbrook stream, heading for the test sites on the plateau of Kinder. The Moors for the Future team was led by Tom Aspinall, Research and Science Officer, and Trish Justin, a casual employee who by her own admission tends to do the 'fun stuff' of monitoring out on the moors while supervising volunteers such as those today: Sally Hunter, Graham Berry and Paul Hatt.
This is not volunteering for the faint-hearted as Kinder is difficult walking, particularly on the plateau once the paths have been left behind. It helps that many of the staff and volunteers are fell runners, and Trish has gone one further: she is a triathlete, too. Like volunteer Graham she has been running these moors for 20 years or more and she and her friends remember how they were before the restoration work began.
'When we first used to run out on Kinder it was still in a poorly degraded state, bare peat everywhere, very messy to run through,' she says. 'But people I run with, who come out on the moors regularly, have all commented on what a change it is, the moors have gone from that horrible black to a lovely green cover. Even though that is still in the early stages, we are working towards creating a much more mixed and diverse moorland plant community up there, it is ongoing.'
There is a sharp, chill breeze blowing and the brook beside us is full and stained tea-coloured by peat. The bracken is bronze and russet in the bright sun and the plateau looms above us, its guarding rocks stark against a blue sky. If we can see the top of Kinder at all it is a good day, weatherwise, I say.
Just before the final ascent we escape the wind by hiding behind a boulder for a few minutes, while Tom tells me something about the science that is going on up here. The idea of the yearly 'dipwell monitoring' is, he tells me, to check on the progress of the big restoration works, that it is having the desired effect on the ground. Checking that 'it is going in the direction we want it to, back to a blanket bog state.'
'By having a blanket bog in a healthy condition, the work that we are doing is hopefully going to slow that water down,' Tom says, 'and stops a massive deluge coming off the moors in an instant, so streams and rivers further down aren't bursting their banks quite so often.'
If I was expecting to find these scientists using complicated 'high-tech' equipment, then I was to be disappointed. The equipment they use to determine the level of the water table is child-like in its simplicity. At the test sites there are pipes sunk down into the peat and a volunteer will then thread down a flexible tube and blow until they hear bubbles - when they know they have reached water. Then they measure the length of the pipe with a folding joiner's rule.
But as volunteer Paul later demonstrated to me, as he knelt on the ground with the tube at his lips, moving it up and down the pipe: there is more to blowing bubbles than you might at first think. He blew a particularly rasping set of bubbles: 'That is because I am just too far into the water,' Paul says. 'I've got to find the point at which I am just touching the top of the water. And that is a much quieter sound.' He adjusted the tube and blew again. It was. And the level was noted.
Tom tells me that a healthy blanket bog should have the water table about 10cm beneath the surface of the peat. So far they have 10 years of data, and the trend is clear that in the revegetated areas the water table has risen in relation to the 'control' areas, where the peat has been left untouched. This is good news as far as 'slowing the flow' of the water into our rivers is concerned, and ultimately in helping to prevent its unwanted presence in our front rooms.
I left the dipwell monitors to it at one of their testing sites and wandered out onto the plateau of the moor. It is like a living laboratory now in places on top of Kinder, with universities and Moors for the Future researchers' installations of monitoring equipment. With the solar panels to power the equipment, it looked at times as if aliens had landed.
Some of the main gullies have across them a 'V-notch' weir, which monitors the flow of water from the moor. I spoke to Moors for the Future's Dr David Chandler about their monitoring equipment. A rain gauge monitors how much rain is falling, and the V-notch weir tells them how much of the rain is finding its way into the gulley on the catchment and when, he explains.
'From that we can get all sorts of measurements to do with the total volume that is coming off, and also when the peak rainfall is and when the peak discharge is,' says David. 'That relationship tells you how much of the water is being temporarily stored on site, how long it takes for the water to get from landing on the ground to flowing out from the bottom of the catchment.'
'What you find is that on bare peat there is nothing to hold up the water. You find the peak flow is very shortly after the peak rainfall,' David says. 'Whereas once you have done revegetation and gully blocking having physical stuff in the way - whether the stems of plants or a gulley block - slows the flow of the water down. So the same total amount of water still exits the catchment, but it just does it more slowly, in a more regulated way. So you don't get the kind of big flash flood peak.'
Early research is suggesting that revegetating the moorland and blocking gulleys can slow the flow from between 4 per cent and 30 per cent. This can be significant as, David explains, it tends to be the top few percent of a 'storm event' that tips a big storm over the edge into becoming one that causes flooding.
Work is currently ongoing with University of Manchester researchers to see exactly how significant these Natural Flood Management strategies can be when applied across a whole river catchment. Results are expected in 2021.
As we made our way back along the north edge of Kinder the afternoon sun still shone and the views were spectacular. Sheffield in one direction, and Manchester and its surrounding mill towns in the other. It drove home how these moors loom above our lives and the impact they can have - for good in terms of water and carbon sequestration, the ecosystem services, and yet treat them badly and they can unleash forces to be reckoned with.
We headed down Fairbrook Naze to pick up the trail back to the cars parked on the Snake Pass and I caught up with Moors for the Future volunteer Sally. Sally lives in Whaley Bridge and also volunteers for the Canal & Rivers Trust, recently at the centre of world news when a breach in Toddbrook Reservoir dam wall caused the town to be evacuated during severe summer storms.
'It really demonstrates how important this work is,' says Sally. 'The water level was so high it was jumping out of the rivers. Land management is just going to be really important in the future. It really highlighted why we need to do this stuff - once the water hits that reservoir there is nowhere else for it to go, so it has got to be managed up here.'