Could making rivers bendy again help prevent flooding?

Wednesday, January 17, 2024

In the UK, 97% of rivers have been altered in some way to better suit modern life. On the Knepp Estate in Sussex, they've changed their stretch of the River Adur back to a more natural shape.

When Storm Henk hit the UK in the new year, it brought more than 300 flood warnings and damage to around 2,000 properties across the country.

But while it was devastating, it wasn't particularly extraordinary.

Floods are an increasing danger in the UK.

The Environment Agency says around 5.7 million homes and businesses in England are at risk of flooding and that number could double by 2055, partly because of climate change.

So what should authorities do?

At the Knepp Estate in Sussex, they're making their stretch of river bendy again.

Like many rivers across the country, the Adur has been "canalised" in parts - straightened out like a canal.

The surrounding land was drained in the 1800s to make way for fields, and water from the river rushed down to the sea.

But all these straight rivers cause problems. The water moves through too quickly, bypassing floodplains and ending up in towns and villages instead.

So at Knepp, they're taking the river back to its natural state. Satellite images reveal the difference in shape over the years.

Sir Charles Burrell is the owner of the rewilded Knepp Estate.

"If you straighten [a river], you can speed the water up and get rid of it from your area quickly, but then you've got problems downstream.

"So by meandering it, you're making the water travel further within your landscape. You're also giving the water opportunities to spill out on to the floodplain itself."

They've also created scrapes - low bits of land that fill with water - and have lowered the banks of the river so more water can splash out, as well as making it shallower in parts.

It's all part of an attempt to make the river flow more naturally - which means it will flood their land.

Melanie Sanders is the river restoration specialist at Knepp, and thinks floods have been unfairly maligned.

"I think we perceive flooding as a bad thing because we see it flooding things that we don't want to flood," she said.

"So roads and houses being flooded is obviously bad, but flooding is meant to happen.

"Rivers do use their floodplains and we need that space for flooding, but we need it to be in the right place, out of harm's way.

"So restoring a river like this to function with its floodplain means that we're holding water where it's meant to be and the roads, towns and houses further downstream have less water hitting them all at once."

In the UK, 97% of our rivers have been changed in some way to better suit modern life.

So is stopping flooding as simple as just returning all of these rivers to their meandering shapes and connecting them back to their floodplains?

Dr Gareth Old, a hydrologist at the UK Centre for Ecology and Hydrology, says not.

"If we look at the floods we've had recently, river restoration wouldn't have stopped those," he said.

"The river channels and the soil, everything was saturated and full of water, so the floods propagated downstream.

"However, if we look at small to medium events, then there is potential to make a difference and reduce the impacts."

The other problem is practicality. These rivers have been changed over decades and now there are homes, farmland, businesses and roads on what was once a floodplain - so it's clear this is not a solution that will work everywhere.

David Exmoor farms the land around the edges of the Knepp Estate and says this practicality has to be taken into account.

"We don't live and work in a wild landscape," he said.

"This is a managed landscape. And we need to manage the river."

Source: Sky


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