February 17th, 2014

Fools rush in where angels fear to dredge

7 minute read

by Peter Jones


The flooding that has struck the UK in recent weeks has brought misery and loss to households and travellers in several parts of the UK. In the resulting atmosphere of near-national emergency, our politicians have produced their own deluge of regrettable remarks. Enraged Somerset MP Ian Liddell-Grainger’s comment that he would “stick [Environment Agency chief Lord Smith’s] head down the loo and flush” in order to get his message across takes some beating, However, Nigel Farage’s call for the foreign aid budget to be deployed in Somerset was so daft that even Eric Pickles called it an “easy” and “populist” hit. Of course, the man who published the “bin bible” earlier this year knows whereof he speaks….

Mr Pickles has been standing in for Environment Secretary Owen Paterson, who would have been the man in the eye had he not been the man in eye surgery. I don’t know how much of a hydrologist Pickles is, but he’s been eager to wade in and join the stream of abuse from politicians, Somerset residents and many others directed at the Environment Agency’s decision to cut back on dredging and work. He commented that, “it was a policy not to dredge and the more we know about it the more we know it was a wrong-headed decision.” Apologising for the flooding, he said “I am really sorry that we took the advice … we thought we were dealing with experts.”


Parrett fashion

I can’t claim to be an expert on rivers, still less on the very particular circumstances of the rivers of the Somerset Levels. This low-lying area has gradually been reclaimed from marshland by generations of engineers, who from mediaeval times through to the 1970s have embanked rivers, dug drains and installed pumps. But even focused on such an exceptional area, the ease with which consensus is forming around a policy that lacks expert backing and a narrative that places blame on the Environment Agency is troubling. A potentially damaging connection is being formed in the public consciousness between dredging and flood prevention as politicians, instead of accepting that they were out of their depth in this complex policy area, queued up to repeat the message: “dredging prevents floods”.

It isn’t as though the Agency has been sitting on its hands in Somerset. It has been maintaining the rivers of the Levels: last October it started a programme of de-silting work at ‘pinch point’ locations on the Rivers Tone and Parrett. But it hasn’t just been looking to improve the flow of rivers. At the same time it has been participating in a task force set up after the last floods in 2012/13. This brought together Somerset County Council, the Somerset District Councils, the National Farmers Union (NFU), the Somerset Consortium of Drainage Boards, the Farming and Wildlife Advisory Group, Somerset Wildlife Trust, the Royal Society for the Protection of Birds, and Natural England to produce a joint Vision 2030 document.


Setting the Tone

Alongside river management, the document envisages managing flood plains to accommodate winter flooding; a landscape containing a mix of agricultural land and wet grassland; an end to unsustainable farming practices; and the reconnection of currently fragmented fen and flower-rich meadows. The chairman of the task force, retired NFU representative Anthony Gibson has been amongst those calling for dredging of the Tone and Parrett; but he does so with an appreciation of the particular characteristics of the area.

The extensive embankments mean that in some areas, river levels can be as much as 10 feet above the surrounding landscape. As a result, when the banks are overtopped, flood water cannot run away until river levels have subsided considerably. Flood water can become stagnant, de-oxygenated and polluted, meaning that it can’t be pumped back into rivers without chemical treatment. The result is massive damage both to agricultural land and wildlife areas. Mr Gibson therefore sees maintaining the carrying capacity of rivers as key to protecting agriculture, homes and wildlife. But he also states that dredging would have reduced, but not prevented this winter’s floods; and points out the need for other measures: “action to reduce the speed and volume of run-off from the upper catchment is essential”.



High water levels:flooding in Somerset has no easy answers. Photo by Nigel Mykura, via Wikimedia Commons.


The Somerset Drainage Boards Consortium also gives a clear mention to dredging in its recently published 10-point plan for the Levels, but recognises the role tides have in flooding in the area with a proposal for a tidal sluice on the Parrett. They also highlight the need to reduce urban run-off, to get landowners to fund flood risk management work on their property, and the promotion of adaptation. Similarly, the national Association of Drainage Authorities 10-point plan talks carefully of the limited role of dredging:

“Where the lower parts of a catchment are artificially drained, channels and ditches must be maintained to transmit excess water through the area into the sea as quickly as possible.”


Scraping the bottom of the channel

De-silting has its place in an artificial landscape such as the Somerset Moors and Levels, but even there it has to sit alongside other measures. This nuanced message and the downsides of dredging are getting lost in the clamour. Dredging is:

  • Expensive: even the work the Environment Agency undertook on pinch points at on the Tone and Parrett was expected to cost £3.5m.
  • Temporary: silt washes downstream (or even upstream in tidal waters) and rapidly re-accumulates in areas that have been dredged. Floods can mobilise large amounts of soil, so that dredging must be repeated frequently. Where dredging results in plants and roots being removed from river beds or banks, it can lead to more potential for silting.
  • Often ineffective:  Dredging river channels doesn’t give them limitless capacity.  A river channel is small compared with the surrounding flood plain and when extreme weather even the most heavily maintained river won’t be able to cope. Removing silt in an area may help prevent flooding there, but simply move the problem downstream.
  • Damaging: removing material can disrupt fish spawning grounds, interfere with wetlands and destroy the habitats of animals that dwell in river banks.


It isn’t just the sandal-wearing fraternity saying this: the Chartered Institution of Water and Environmental Management (CIWEM) has just published a report giving a “reality check” on the role of dredging in flood prevention, a timely reminder that other means of managing rivers may be more cheaper and more effective. They are joined by former Environment Minister Richard Benyon, who warned of the dangers of politicians acting as “armchair hydrologists”, looking for scapegoats and making policy in the teeth of a crisis.

Faced with an emergency, it is natural that we reach for solutions. It’s hard to listen to the advice of those whose approach is widely perceived to have failed. However, what Defra and the Environment Agency are guilty of is sticking to their spending rules which require flood prevention measures to demonstrate a cost-benefit ratio of 1:8. Choosing the highest impact projects is hard to argue with – unless you live in an area denied protection because the business case doesn’t stack up. If expenditure is going to be constrained, the inevitable result is going to be that in the extreme weather that seems increasingly frequent, some areas will flood.

One point that struck me in the CIWEM report was their call for better land management to help slow water down and reduce the amount of eroded soil that clogs rivers up. Changes to ploughing techniques, planting cover crops and reduced grazing are all highlighted. For any reader of George Monbiot’s recent book Feral, it’s interesting to see how mainstream ideas such as upstream woody debris dams and reforesting of both uplands and floodplains now seem to be. Other measures recommended include the wider use of measures to reduce urban run-off, such as more permeable paving and green roofs and walls.

The man responsible for the silliest comment made about river management in recent times was Owen Paterson last April. He told the South West Agricultural Conference that “The purpose of waterways is to get rid of water.” When large parts of the country are under water, perhaps it’s natural that the people affected should start to think of rivers primarily in terms of their role in drainage. But when the Environment Secretary seems to regard rivers as just an unreliable part of the nation’s plumbing, it almost makes you glad that they put Pickles in charge.


Peter Jones


Peter Jones



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8 Comments on "Fools rush in where angels fear to dredge"

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Nicolay Kiselev

I agree with John Mathias and consider that opinion “dredging prevents floods” is wrong.

W Alexander H Hamilton
W Alexander H Hamilton
“The man responsible for the silliest comment made about river management in recent times was Owen Paterson last April. He told the South West Agricultural Conference that “The purpose of waterways is to get rid of water.” ” – Not really so silly if you read “waterways” to be “rivers” in the present context- you do not need a degree in geomorphology to know that the only way rivers are ever created is by the water from rainfall and springs finding its way to the sea. Maybe “get rid of” is a crude way to describe river flow – but… Read more »
Peter Jones
I can’t fail to agree that rivers have the effect of transporting water from land to sea; but the reductionist view that this is their sole “purpose” seems eminently silly, even in the context of recent floods. Aren’t they also sources of water for irrigation; habitats for fish, birds and animals; opportunities for leisure pursuits; part of our transport infrastructure; aesthetically pleasing; and no doubt many more “purposes” besides? We need to keep in mind the full range of roles that rivers play if we’re to avoid making bad policy. I’ll happily concede that the main purpose of a storm… Read more »
W Alexander H Hamilton
W Alexander H Hamilton

Not sure where my last comment disappeared. Anyway, all those lovely “purposes” for rivers ( as opposed to canals) that Peter Jones listed, namely “sources of water for irrigation; habitats for fish, birds and animals; opportunities for leisure pursuits; part of our transport infrastructure; aesthetically pleasing;” are incidental (and frequently manmade) to the only fundamental reason (which can be anthropomorpized as “purpose”) that is always present for a river ( as opposed to a canal) – that is: carrying water downhill from the land to the sea. Mr Paterson was right.

John Mathias
Peter, Having grown up on the Somerset levels and spent many a happy hour swimming in rivers and drainage channels and jumping rhynes I have to say there seems to be a fundamental lack of understanding by both politicians and many of the residents. The levels are a flood plain and below sea level therefore they are going to flood. The rivers cannot drain into the sea if there is a tidal surge forcing water inland and the tidal rise and fall in the Bristol Channel is the second largest in the world . Much of the silt that those… Read more »
Helen Ridler
I agree with your statements regarding management of the entire catchment with regard to re-wilding to slow water and the creation of additional storage. I would like to add to this that something needs to be done regarding the currently uncontrolled urban run off that has been created by poor planning decisions and over development of marginal land within the catchment. This issue and the rectification of mistakes already made are being proposed as part of the new 20 year plan being drawn up by the County Council. However, I must take exception to your assumption that most of the… Read more »
Andrew Herkes
It seems to me that many of the people affected knew the Levels were reclaimed marshland and thought no more they just moved in.I am no hydrologist but it takes no expert to know that reclaimed marshland is always liable to flooding – raised river banks gives a clue too. The people moved in to their counrtyside idyl without even a basic thought. Even the searches on buying the properties did not concern them. They move in and then complain when the inevitable happens and start shouting “They arenn’t doing anything” “they should have …..” What about all the other… Read more »
Mike Brown
Peter I find it hard to be a fan of the Agency – it’s always felt just too big and clumsy. But I’m even less of a fan of opportunist politicking which this bout of EA bashing surely is. Am I the only person seeing the irony in climate-sceptic politicians attacking the EA. Aren’t the EA the government’s expert on the environment? Haven’t they been warning about the impact of climate change? Haven’t they been asking for more money to mitigate the effects of increasingly hostile weather patterns? In his pretty impressive interview on Today last week, Lord Smith very… Read more »