How a UK river serves as a natural lab for flood defence research

How a UK river serves as a natural lab for flood defence research

Lake Wooden is a part of Eddleston Water, a stretch of river close to Peebles, UK

Colin McLean

After I go to a analysis lab, I don’t usually count on to must dodge sheep or get my sneakers muddy, however this lab is much from regular. I’m strolling on farmland, about 30 kilometres exterior of Edinburgh, UK. The air is crisp and I can hear a river babbling as I strategy.

It’s this stretch of river, often known as Eddleston Water, that I’ve come to see, guided by Chris Spray on the College of Dundee, UK. Working with the native environmental charity Tweed Discussion board, Spray and his staff began learning the river in 2009 and it has been residence to a sequence of real-world experiments ever since. They name it a “pure lab” for river science.

Save Britain's rivers

As we watch a dipper hovering out and in of the river seeking prey, Spray tells me that the lab was initially set as much as reduce the flood danger dealing with Peebles, a city of 9000 folks, that sits on Eddleston Water.

Spray and his colleagues wished to learn the way they might reduce flood danger utilizing nature-based options, similar to tree planting, fairly than constructing synthetic dams. Extra importantly, additionally they wished to learn the way efficient these strategies actually have been. “Fashions are nice and all, nevertheless it’s solely with real-world information that you simply get a full understanding of all the assorted components that may have an effect on these outcomes,” says Spray.

Such strategies, also called pure flood administration (NFM), are gaining traction: the UK authorities plans to double the variety of flood discount and coastal erosion initiatives in England utilizing NFM from 60 to 120. However, regardless of this, the proof base for NFM is comparatively sparse, says Spray.

One massive query in hydrology is what occurs once you make a river bendier, in any other case often known as re-meandering. Lots of the UK’s rivers have been made artificially straight, releasing up room for roads and railways, however we now know this additionally will increase the chance of floods. The thought goes that re-meandering rivers permits them to carry a better quantity of water and so keep away from flooding.

But Spray’s staff has discovered that, at the very least in Eddleston Water, re-meandering alone doesn’t seem to have a serious impact on flood danger. It’s because the floodplain surrounding the newly flexible river isn’t notably giant, so can’t successfully retailer the water that overflows because of extra rain. However that doesn’t imply there aren’t advantages: a bendier river has an enormous profit for ecological range, says Spray.

For instance, the staff discovered a rise within the variety of spawning habitats for salmon in re-meandered sections of the river. This is without doubt one of the the explanation why the dipper is attempting its luck within the river at present, says Spray.

A better take a look at the river additionally reveals the assorted methods wherein the water appears to movement – it’s far quicker on the bendier bits, which comprise extra oxygen and may give rise to a better number of insect life. These elements of the river merely appear extra alive than the unrestored sections.

The researchers have additionally studied leaky dams, that are merely tree logs positioned throughout a stream. Throughout regular river movement, the water passes beneath the logs, however when river ranges rise the dams cumulatively gradual the movement of water.

Spray reveals me one among these dams, comprised of a dozen logs mendacity throughout a stretch of the river. It appears to be like messy, extra like particles than one thing positioned by people, however Spray says these haphazard logs have most likely had the most important influence on flooding in Peebles of all of the interventions they’ve trialled. “You wouldn’t assume it them, however they’re such a simple and simple answer to chopping flood danger.”

Past flood danger, the staff has quantified the financial beneficial properties of its interventions. “Cash talks,” says Spray. The researchers say that NFM has helped keep away from £950,000 value of flood damages within the 10 years for the reason that first interventions have been put in in 2012. However that is far outweighed by the ecological advantages to the area, similar to improved carbon storage and elevated water high quality, which the staff values at round £4.2 million. “That is what pure flood administration can do this merely constructing flood defences can not,” says Spray.

However pure labs include their very own issues. Spray says the lab’s experiments are sometimes a compromise with the handfuls of landowners within the space, fairly than excellent science. Re-meandering takes plenty of house and farmers could produce other plans for that land, says Spray, so the staff’s efforts have been scaled down from the best. “If the landowner doesn’t need it to occur, it doesn’t occur,” he says. “We don’t push our luck.”

That additionally factors to a much bigger drawback with NFM. For it to work throughout the UK, river practitioners must foster nearer relationships with landowners, says Spray. However that’s simpler mentioned than completed and takes time. “We’ve been right here for over a decade,” he says. “The belief has been laborious fought for.”

One answer is to pay landowners to make use of NFM, one thing the UK authorities is planning on doing as a part of its post-Brexit farming reforms, though the small print haven’t but been revealed. Spray hopes this may assist enhance the take-up of his staff’s analysis. “However these methods solely work should you get farmers on board – it’s essential make it value their whereas,” he says.


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