the issues around flooding: to dredge or not to dredge

Within the debate on flooding and climate change there has been a tussle over how much the dredging of rivers - or its absence - has been to blame:

Flooding chaos is down to David Cameron, not climate change

The Environment Agency's failure to dredge clogged-up rivers is causing floods

By Christopher Booker 11 Jan 2014

Instead of revealing that he has no idea what he is talking about, Mr Cameron might concentrate on the real causes of the genuine problem highlighted by the recent flooding, which has affected so many parts of the UK, not least the vast area of the Somerset Levels. I have been talking to a team from the Royal Bath & West agricultural society, who are admirably and expertly trying to find a practical solution to the damaging floods that in recent years have wrought havoc on a sixth of our county, not only in the winter, which is customary, but even, as in 2012, for months of the summer.

There is no doubt that a central part of this problem lies in the refusal ofthe Government’s own Environment Agency, since it took overall responsibility for draining the Levels in 1995, to dredge the main rivers, which are so clogged up that they can no longer carry away the run-off from flooding. This is exacerbated by the fond belief of so many there, and in that other government agency, Natural England, that the Levels should be allowed to return to the swampy wilderness that they were before being drained by Dutch engineers in the 17th century. (A former head of the Environment Agency was heard to say that she would like to “attach a limpet mine to every pumping station”.)

Flooding chaos is down to David Cameron, not climate change - Telegraph
Dredging will ease flooding in Somerset Levels, admits Environment Agency boss - Telegraph

Victims of the Somerset floods fought for rivers to be dredged but that may not end their misery

Andrew Gilligan 02 Feb 2014

Only 10 days ago, faintly “swampist” conservation groups such as the Royal Society for the Protection of Birds – a big landowner in the area – were opposing “backward-looking 1960s-style dredging.” By Friday, the RSPB had come out in favour of dredging. Last week, too, after years of prevarication by government, David Cameron promised to make it happen.

Dredging is not, of course, a magic answer. The main cause of the current flooding was not the failure to dredge the rivers, but last month’s unprecedented rain – in Somerset, around three times more than the January average. As of last week, there were about 14 billion gallons of water lying on the Levels. Even if every local river had been dredged to its maximum extent, it would not have been able to soak up anything like that much.

“Dredging would have made little difference,” says Prof Thorne. “The floods this year and last are serious events that would overwhelm most flood defences.”

Alterations to the landscape in the wider catchment area – the 50-mile-wide bowl of land running down to the Levels from the surrounding hills – also mean water arrives in a faster and more concentrated way than it used to, making it harder for the rivers to cope. Changes in the catchment, such as tree planting, are needed, and will take years.

Yet, as Mr Gibson says, the authorities have clearly been “in denial” – or worse – about the help dredging could give.

Even last week, the Environment Agency’s chairman, Chris Smith, was saying that it would make only a “small difference” in the future. Alas for Lord Smith, it turns out that the agency did in fact do detailed computer models of the impact of dredging on the 2012 Somerset Levels floods. Copies of this modelling, obtained by The Telegraph, show clearly that dredging the two main rivers, increasing their capacity by about half, would have “significantly reduce[d] the duration and depth of flooding” in the worst areas.

So desperate were the people of the Levels for dredging that they actually launched a charity appeal, the Somerset Levels Relief Fund, to pay for it. Now, however, it looks like the Government will pay.

Whatever happens after the waters retreat, life on the Somerset Levels will never be quite the same.
Somerset floods: 'Is this area for people to live in or for animals?' - Telegraph

There are other opinions:

It is clear to see, reflecting back on the floods of 2007 (and those in 2005 and 2009), the lack of integration and disjointed policy across the two central government departments has still not been resolved seven years later. The fixation with dredging continues, and David Cameron has called for dredging to start as soon as possible, reversing previous statements that it would be little help.

The inconvenient truth: houses built on floodplains could flood

Dredging rivers won't stop floods. It will make them worse

David Cameron pledges to pursue a policy in the Somerset Levels that will only lead to more dangerous rivers. But it keeps the farmers happy

George Monbiot

The Guardian, Thursday 30 January 2014 14.30 GMT
Jump to comments (592)

For a moment, that rarest of beasts – common sense – poked a nose out of its burrow and sniffed the air. Assailed by angry farmers demanding dredging in the Somerset Levels, the environment secretary, Owen Paterson, broke with time-honoured protocol and said something sensible: "Dredging is often not the best long-term or economic solution and increased dredging of rivers on the Somerset Levels would not have prevented the recent widespread flooding."

He went on to suggest something I never thought I would hear from his lips: "Also, we need to do more to hold water back, way back in the hills."

Coming from the man who insisted in November that he would do what he could to help farmers keep the hills bare, this was an astonishing and welcome turnaround. It reflects what his advisers in the Environment Agency have been trying to say for years, before being sat on by ministers wanting instant answers to complex problems and then – as the government still plans – being sacked in droves.

A presentation by the agency, called To Dredge or Not to Dredge?, spells out the problems in terms that even ministers can understand: "The river channel is not large enough to contain extreme floods, even after dredging. Dredging of river channels does not prevent flooding during extreme river flows … The concept of dredging to prevent extreme flooding is equivalent to trying to squeeze the volume of water held by a floodplain within the volume of water held in the river channel. Since the floodplain volume is usually many times larger than the channel volume, the concept becomes a major engineering project and a major environmental change."Dredging rivers won't stop floods. It will make them worse | George Monbiot | Comment is free | The Guardian

Dredged Up | George Monbiot

And the debate is fiercest in Somerset:

 

SOMERSET FLOODING: To dredge or not to dredge - battle lines drawn over floodings on The Levels

By WMNPBowern  |  Posted: January 20, 2014

A bitter battle over the best way to manage the Somerset Levels has erupted after floodwater inundated the area for the second time in two years. Much of the low-lying landscape, no stranger to disputes between farmers and conservationists, is still under water after weeks of heavy rain that first hit the Westcountry over Christmas. Somerset Conservative MP Ian Liddell-Grainger has secured an adjournment debate in the House of Commons on Wednesday next week, at which the cost to the local commumity of the floods will be debated.

Two sides have their say in debate over whether Somerset rivers shjould be dredged to help flood waters to drain away | Western Morning News


CLYST ST MARY:

Is it a matter of 'people before birds'? Some residents along the Clyst Valley feel this is how their predicament is being veiwed:

Save the Clyst is a collection of concerned locals and landowners opposing the plans by the Environment Agency and RSPB to flood the valley for "Habitat Creation". This is an Orwellian term to describe habitat destruction



Sunrise on the Clyst this morning. A mature environment, where nature and man coexist in balance. Occasionally, nature overwhelms us, and it floods a bit. All within the bounds of what we expect. We do NOT expect, however, in this time of diminishing resources and increasing flooding, to be pressured by the Environment Agency to flood land to satisfy their unscientific whim.

Save the Clyst | Facebook

An EA spokesman said: "The flooding in the Clyst Valley and across the region in recent months was due to high river flows following exceptionally heavy rainfall. It followed one of the wettest summers on record. It was these high river flows that caused the road to flood as opposed to a deliberate land management and habitat creation policy on the part of the agency.

"It is likely the road could flood again if we experience similar rainfall patterns and river flows in the future. The existing defences have not been modified and I can confirm the agency will continue to protect people and their houses from flooding."

Topsham flooding fears over EA plan | Exeter Express and Echo.
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