Several storms have resulted in widespread flooding across the UK over the past couple of months, with Cumbria, Lancashire, Greater Manchester, Yorkshire and parts of Scotland, Wales and Northern Ireland among the worst affected. Cities such as Leeds and York were forced to a standstill. We certainly can’t control the weather and climate change is bringing with it far more volatile barometric lows. This we will have to live with. However, policy can at least influence where the water goes once it reaches the ground. This post questions why we continue to follow the same policy of dredge, dredge, dredge when time after time it hasn’t been working? Dredging not only costs huge amounts of money and needs to be repeated time after time following each flood, it is fundamentally a risky strategy, as will be explained in this post.
In an appearance to the House of Commons Liaison Committee David Cameron recently said:
You’ve seen quite an attitudinal change in the Environment Agency that in years gone past, I think, were trying to balance up the effects on nature on the one hand and protecting property on the other hand. We’ve said to them: ‘The time for that is over. This is about protecting human lives. This is about protecting our homes.’
Cameron was suggesting that people need to be put before the natural world in managing flooding risk. However, he completely sidelined the answer that is staring us in the face: by using nature we can help mitigate the effects of flooding. We need a cultural shift in attitude that encompasses a wholehearted change in thinking behind upland management, using the environment to slow water movement, not a continuation of further quickening of water through the catchment and a greater amount of dredging.
So, why is dredging not the answer? Why is it such a risky strategy?
A presentation from the Environment Agency entitled ‘To Dredge or not to dredge?’ (sadly not still available online but taken this quote from an article written in 2014 by George Monbiot who referred to the presentation) spelt the situation out clearly in terms that are easy to 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.
This all seems fairly obvious stuff. In times of heavy rainfall the amount of water we expect the river channel to hold increases even more and even from my very basic understanding of hydrology it is clear that the river is going to burst its banks somewhere along the line. Dredging is a risk because it does not provide a guarantee that communities will not flood and in speeding up the flow the potential problem is made worse (come to think of it any flood management strategy is not guaranteed to work but at least the problem can be mitigated by using other measures).
Even former Environment Secretary Owen Paterson said when the Somerset Levels were last flooded:
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.
From a wildlife point of view dredging causes further issues. Removing gravel from the beds of rivers leads to the loss of spawning grounds for fish – this is something I was made more aware of by the Rivers Trust at the Oxford Real Farming Conference last week. Dredging can also disturb the habitat of otters and water voles. This particular point is one that David Cameron would probably turn his nose up at having said what he did to the Commons Liaison Committee.
Instead of dredging we should be:
- Planting more trees in the uplands and protecting bogs.
- Allowing rivers to flood into their natural floodplains away from homes and relieving pressure downstream. Farmers should be paid through Countryside Stewardship to provide these options to mitigate the risks of flooding elsewhere
- Rivers should be allowed to create more natural meanders and oxbow lakes to slow the flow. This can be done by de-canalising steep banks.
- Understanding the effects of winter cropping on flood risk
- Improving the state of our soils to allow for improved water percolation and water holding capacity
- Creating a landscape scale strategy that encompasses the entire water catchment from source to discharge
- Mitigating flood risk by allocating ‘mitigation areas’ that are flooded in a controlled manner.
Above: The Thames floodplain at Shiplake.
Now, clearly the upper catchment cannot hold all of the water back in times of heavy rainfall and areas of floodplain must be expected to flood. However, this could be redirected to fields rather than homes. Now, I realise this means I am advocating flooding farmers’ fields and with farming in my DNA this makes me slightly uncomfortable. However, farmers are part of a wider community in this country and we need to think logically over the potential cost of the overall picture. I agree with Monbiot that we have to make a choice between flooding fields and flooding homes and buildings. The eventual cost is much greater in the latter situation. Farmers should be compensated but I really believe that a policy which acts to prevent flooding urban areas as much as possible is the best option available to us.
Environment Secretary Liz Truss recently announced that farmers will be able to dredge all watercourses without regulation to prevent their own land from flooding. This might be brilliant for farmers but what about everybody else? It is creating a situation that in the long run will simply lead to more problems downstream.
The NFU, farmers and Countryside Alliance may call me a traitor by saying this but it goes back to my overall philosophical point of view that it shouldn’t be about ‘them’ and ‘us’. We are all part of a wider community and need to act to support each other. In return for having some of their land flooded, farmers must be compensated. However, the land set aside to flood will be managed in a different way. It will be set aside for the very purpose of mitigating flood risk and holding water if the rivers flood.
Above: Alkborough Flats managed realignment scheme, North Lincolnshire
Managed realignment schemes are a case in point of protecting against flooding – in this case on the coast. On our own farm in Essex we realigned the sea wall five years ago, resulting in a new habitat which floods twice a day. Previously it was a rather poor grazing marsh that made very little money and did little for wildlife. The project has been a great success both in terms of relieving pressure on the rest of the sea wall as well as improving biodiversity on the farm and boosting farm income.
It is a similar idea I am advocating for inland water courses. Schemes should be created which encourage farmers to mitigate flood risk. If flooding and flood management is worked in to land use management strategy then we will not be caught out unawares and the resultant problems will not be as drastic.
George Monbiot has written a wealth of articles on flooding and I recommend you read them if you want further information on the type of approach I am advocating: