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Somerset Floods Update

March 9, 2014
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By Paul Homewood

 

A resident looks at a banner that has been put on the bridge at Burrowbridge

 

As the waters thankfully begin to recede on the Somerset Levels, it is time to take stock of the last three months.

After a drier than normal November, the rain began falling in earnest in the second week of December, and only began to abate in towards the end of February.

Met Office regional statistics for SW England & S Wales extend back to 1910, and according to these, the December to February period just ended recorded the highest precipitation on record, with 670.6mm. However, this does not tell the whole story, since other years have recorded higher 3-month totals, as Table 1 shows.

 

  mm
Nov 1929 to Jan 1930 812.2
Oct 2000 to Dec 2000 700.8
Dec 2013 to Feb 2014 670.6

Table 1

 

 

Altogether, there have been six winters including this one, where precipitation has exceeded 600mm over a 3-month period. As well as the three above, there has also been 1959/60, 1960/61 and 1989/90. It could therefore be argued that what we have seen this year is a once every 15-20 year event.

 

While this year’s heavy rain was spread over three months, it should be borne in mind that in other years the unusually wet weather extended for four consecutive months.

The average monthly rate from October 1929 to January 1930 was 251mm, which was more than this winter’s three month average of 223mm.

 

  mm
Oct 1929 to Jan 1930 1005.4
Oct 1960 to Jan 1961 778.2
Oct 2000 to Jan 2001 820.8
Nov 2013 to Feb 2014 777.8

 

Table 2

 

Local Data For Somerset.

Is the regional data representative for Somerset itself?

Unfortunately the Met Office data for the local station at Yeovilton only dates back to 1964

However, the old British Rainfall publications have a wealth of data, until they were ceased in 1991. (I’m not sure what this says about the Met Office’s transparency!). These publications give us monthly rainfall data for several stations in Somerset, including Street, which is within about 15 miles of Yeovilton. They are both low level stations, so we should be able to directly compare them.

(Also, the 1961 British Rainfall shows that annual rainfall for Street and Yeovil was 28.1 and 28.6 inches, respectively, so Street appears to be a reasonable proxy for Yeovilton.)

Table 3 compares rainfall at Street in 1929/30, with this winter at Yeovilton.

 

Street mm Yeovilton mm
Oct 1929 119 Nov 2013 57
Nov 186 Dec 121
Dec 145 Jan 2014 166
Jan 1930 93 Feb 129
4-Month Total 543 4-Month Total 473
 
Table 3
 
We find that 1929/30 had the rainiest month, the wettest 2-month period, the wettest 3-month period, as well as the wettest 4-months.
It is also worth noting that the October-December 2000 period also totalled 416mm, the same as this winter.
 
 
1960/61
It is noted above that Oct 1960 to Jan 1961 was a similarly wet period, but in fact this was part of a much longer period of exceptionally wet weather, which had begun in July. The Met Office summary for Nov 1960 mentions that :
 
image
http://www.metoffice.gov.uk/media/pdf/o/r/Nov1960.pdf
 
(This record has not been beaten since either).
 
 
We can compare recent rainfall totals with 1960.
 
 
Street mm Yeovilton mm
July 1960 128 July 2013 40
Aug 139 Aug 15
Sep 84 Sep 67
Oct 197 Oct 115
Nov 86 Nov 57
Dec 76 Dec 121
Jan 1961 112 Jan 2014 166
Feb 82 Feb 129
8-Month Total 904 8-Month Total 710
 
Table 4
 
Of course, summer rain is more likely to evaporate or be absorbed. Nevertheless, it does indicate that river levels in September 1960 would have been much higher than last summer, exacerbating some of the particularly severe floods to follow in the autumn.
 
Although October 1960 had by far the highest rainfall total, (which has not been exceeded at Yeovilton for any month since 1964), and the total rainfall over the full period was much greater, that year did not have the same concentrated 3-month spell as this winter.
Nevertheless, there were still disastrous floods in Somerset and the South West that autumn. Taunton was particularly badly hit in October.
 
 
Somerset County Gazette: Photos from the Taunton Flood of October 27, 1960.
 
 Photos from the Taunton Flood of October 27, 1960.
http://www.somersetcountygazette.co.uk/news/galleries/taunton_floods_1960_photos/view/gallery_178664.Taunton_Floods_Photos_1960/
 
 
 
Meanwhile, Exeter suffered huge floods in October, and then two months later in December.
 
 
Floods in 1960 near Beach Brothers
 

Okehampton Street, Exeter, October 1960

http://www.exetermemories.co.uk/em/exeter_floods.php

 

Long Term Trends

 

Finally, let’s have a look at the record since 1910, to see if there is any trend towards increasing rainfall during the heaviest rainfall months of September through February.

This year’s total ranks third behind 1929/30 and 2001/01, but the 10-Year trend has actually been falling during the last decade, and at 742mm is close to the mean of 733mm.

 

image

 

 

Summary

Heavy rainfall in Somerset this winter has been unusual for its duration of the best part of three months, but nevertheless is by no means unprecedented. As with the country as a whole, rainfall in 1929/30 was both much more intense and longer lasting. Another four years had comparable episodes to this winter.

Meanwhile, there is no evidence that winters are becoming wetter.

The bottom line is that the flooding on the Somerset Levels this year cannot be blamed on climate change.

 

 

References

1) Regional data

http://www.metoffice.gov.uk/climate/uk/summaries/datasets

 

2) Data for Yeovilton

http://www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/yeoviltondata.txt

http://www.met.reading.ac.uk/~brugge/PREV.html

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4 Comments leave one →
  1. D.M. permalink
    March 9, 2014 7:36 pm

    You are spot on Paul. Nature does not recognise our human calendar. However it is often useful to those who try to promote their own agenda to sensationalise a “unique” event, but in the real world it is meaningless. The correct thing to do is to take a 3 month (or similar) period, whichever date it starts on, and compare with another 3 month (or corresponding) period which you have done. The Met Office won’t like it!

  2. Thomas Fox permalink
    March 9, 2014 8:06 pm

    We must all be able to read the truth instead of a pack lies from our National Media

  3. March 9, 2014 9:23 pm

    It’s likely that there are other ninety day periods with equally high precipitation if one didn’t insist on starting on the first day of a month (i.e. start from the 10th, or the 15th, or the 18th of a month).

  4. neil hampshire permalink
    March 10, 2014 7:31 am

    Are there any local views on the proposed new plan?
    What has happened to Corporal Jones?

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