Dredging is ineffective and will not prevent large floods
I TRUST that W B Carter (Letters, July 30) has carried out numerous studies into the pro and cons of dredging all our rivers to stop flooding. If we stop and think what that would mean to our environment and the fact that dredging is relatively ineffectiv
I TRUST that W B Carter (Letters, July 30) has carried out numerous studies into the pro and cons of dredging all our rivers to stop flooding. If we stop and think what that would mean to our environment and the fact that dredging is relatively ineffective in preventing large floods, perhaps he would change his tune.
Dredging involves stripping the river channel of silt, sometimes stripping out the natural channel itself, a lot of which contains very harmful chemicals from industrial discharges that have accumulated over the years (which is quite safely hidden away in the silt).
Not only would you be destroying habitat for fish, otter, crayfish etc, you would release an extraordinary amount of pollutants into the water, causing serious detrimental effects to wildlife and biodiversity.
If W B Carter got his way and the Environment Agency, at huge expense to the public, made our rivers wider and deeper, we would be left with lifeless chasms with knock-on effects to fishing and tourism, and you would still not have eliminated the risk of flooding.
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Some of the main rivers in our area are artificially maintained at a high level by control sluices and weirs for safe navigation. For example, the River Great Ouse from Bedford through St Neots, Huntingdon, St Ives and down to Earith is controlled by a number of sluices and weirs that can open to allow flood water to pass through.
Dredging, if it is done sensitively, is only necessary on this river to maintain a channel deep enough for boats. It is not going to offer any flood protection, as the hole you dig out is filled with water and the river stays at the same level because it is artificially held up. Therefore the net benefit is zero in terms of reducing river levels.
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Of course the river will be able to convey a bigger flow as the channel will be bigger, but that pales into insignificance when you consider the huge flows and volumes of water during major flood events such as much of the country experienced last summer.
What we really need is a targeted programme of flood prevention measures that reduce the risk of flooding and provide environmental enhancements (not destruction) in areas of greatest risk. Drainage from new housing developments must be delivered in a sustainable manner, so that they do not increase flood risk, nor should they be unnecessarily built in flood plains.
We also need an acceptance that you cannot always protect against flooding, particularly where it is uneconomical to do so. Some people will have to live with the risks if they live or work in a flood plain, and start to take responsibility for themselves, ensuring the house they live in is resilient enough to minimise the damage caused by flooding. And sandbags don't work.
Great North Road