First Phase Of Dredging Completed On Somerset Levels
By Paul Homewood
Work has been ongoing since March to begin the 20-year flood action plan on the Somerset Levels. The main action so far has been to dredge 8km of the Rivers Tone and Parrett. The Environment Agency report that this was completed at the end of October, with the successful removal of 130,000m3 of silt. In the EA’s words:
The work will help to reduce the likelihood and duration of flooding to properties on Curry Moor and North Moor, the A361 and the west Coast mainline.
This is quite a startling admission, given that they were so adamant last winter that there was little they could have done to alleviate the floods. There should really be no surprise about this though, as the EA’s own models confirmed how important dredging was, as the Western Morning News reported back in January:
Anthony Gibson, independent chairman of the Somerset Water Management Partnership and the acting Chairman of the Levels and Moors Task Force, puts the case for dredging.
I don’t really need to make the case for dredging the rivers on the Somerset Levels. The Environment Agency’s computer modelling, carried out in the wake of last year’s floods, has done it for me. This demonstrated that, if the carrying capacity of the Parrett and Tone was restored from its existing 60% of potential to around 90%, the severity of flood events would be, in their words, “significantly reduced”.
What does that mean? Well, last winter, the worst affected area, Currymoor, would have been under water for three weeks, rather than three months, the village of Moorland might not have flooded, the A361 would have remained open for all but a few days and the bills for the eventual pumping out and the flooding-related damage would have been vastly smaller.
Land and Water Services will remain in the area for the next 2-3 months whilst they continue to demobilise equipment from the dredge and use the floating plant to remove any remaining ‘highspots’ of silt that our checking process uncovers . They will also be assisting with our asset repair works including adding localised rock armour erosion protection to the riverbank.
Much work remains to be done, including increasing the capacity of the River Sowy/King Sedgemoor Drain, increasing pumping capacity, repairing river banks and construction of a sluice at Bridgewater.
Previous Floods
One other thing is worth noting. The EA state:
In early 2014 the Somerset Levels and Moors experienced widespread flooding, particularly within the Parrett and Tone river catchments. It is the largest flood event ever known.
The Environment Agency estimated there were more than 65 million cubic metres of floodwater covering an area of 65 square kilometres. Residents of Northmoor (Moorland, Chadmead and Fordgate) had to leave their homes at the height of the flood and many communities were cut off by floodwater.
Records of flooding go back as far as the 1600s and some of the more significant events over the last 100 years occurred in 2012, 2000, 1997, 1960 and 1929.
So how does last winter’s rainfall compare with some of those earlier years?
The worst of the rain, and consequent flooding, last winter occurred in December and January, after a drier than average November. Rainfall in the South West/South Wales totalled 466mm in those two months.
We can compare this with the two month totals of some of the earlier years.
| Rain mm | |
| Nov/Dec 1929 | 607.9 |
| Oct/Nov 1960 | 453.0 |
| Oct/Nov 2000 | 474.1 |
| Dec/Jan 2013/14 | 466.4 |
Clearly last winter’s rainfall was in no way unprecedented, particularly given that November’s rain was 26% lower than normal. The comparison with 1929 is even more stark, as October that year was also unusually wet in the South West, 32% above normal.
If the EA statement is true, that this year’s floods were the largest ever known, it must follow that the lack of dredging and other appropriate action was a major factor.
FOOTNOTE
If you’re wondering where all the silt has gone, the BBC kindly tell us:
Much of the silt which was removed was largely washed in from the Severn estuary. It has been donated to local farmers to spread on their land, in order to enrich their soil.
Everyone’s a winner!
Comments are closed.
NOT A LOT OF PEOPLE KNOW THAT 
I love it. It’s just (almost) like Sir Antony Rupert Jay, CBE CVO, said:
James Hacker: How am I going to explain the missing data to “The Mail”?
Sir Humphrey Appleby: Well, this is what we normally do in circumstances like these. (Hands Hacker the file).
James Hacker: This file contains the complete set of data, except for a number of secret data-sets, a few others which are part of still active analysis, and some lost in the floods of 1929…
James Hacker: Was 1929 a particularly bad winter?
Sir Humphrey Appleby: No Minister, 1929 was a marvellous winter. We lost no end of embarrassing data.
James Hacker: [reads] Some data which went astray in the move to London and when the CRU was incorporated in the University of East Anglia, and the normal withdrawal of papers whose publication could give grounds for an action for libel or breach of confidence or cause embarrassment to the Chief Scientist.
James Hacker: That’s pretty comprehensive. How much does that leave for them to look at?
Brilliant!
There’s no arguing with hard facts, is there?
“It is the largest flood event ever known.”
Such statements are almost always wrong and, also, an indication the speaker has not done the homework. Consider if a woman says to a man – You are the most handsome man in the world. Or a man to a woman – You are the most beautiful woman in the world. All know these are not truthful statements insofar as there are about 3.5 Billion others the speaker has not seen. The speaker wants the one spoken to to believe, and the hearer may believe. So all is well. Still, the statement is not true.
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130,000 cubic meters of silt –
As I recall – at the time an official claimed that silt contained hazardous elements and would be ecologically devastating if dredged. So, are they using this as fill someplace (doing something useful) or are they packaging it in steel barrels and shipping it off to ‘Yucca Mountain’?
phytoremediation
Rice and Milkweed can extract Arsenic from the root zone and Monarch larvae need milkweed. Pass this on to the authorities and have them send my check at least a week before Christmas.
According to the BBC
Much of the silt which was removed was largely washed in from the Severn estuary. It has been donated to local farmers to spread on their land, in order to enrich their soil.!!
http://www.bbc.co.uk/news/uk-england-somerset-28901301
EA computer models. I hope they are more accurate than the ones used to show the effects of climate change