Canadian Underwriter

U.K. 2015/2016 floods one of the century’s “most extreme and severe” flood episodes

December 6, 2016   by Canadian Underwriter

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The winter floods of 2015 and 2016 in the United Kingdom were one of the “most extreme and severe hydrological events of the last century,” a new scientific review has confirmed.

About 16,000 properties in England were flooded over a three-month period. Photo: @BlencathraFSC.

The hydrological appraisal, titled The winter floods of 2015/2016 in the UK – a review, was published on Monday, the first anniversary of Storm Desmond. It brings together both river flow and meteorological data in an analysis of the events that led to extensive river flooding in northern England, Scotland, Northern Ireland and parts of Wales over a three-month period.

The study, carried out by scientists from the Centre for Ecology & Hydrology (CEH) in collaboration with the British Hydrological Society, recognized that the winter 2015/2016 episode ranks alongside the floods of 1947 as “one of the two largest flood events of the last 100 years at least,” the CEH said in a press release on Friday. The analysis in the report was funded by the Natural Environment Research Council.

Storm Desmond alone caused an estimated insurance bill of more than 1.3 billion pounds when it struck on the 5th and 6th of December last year, the CEH reported.

Related: 2015 U.K. storm Desmond loss estimate at 597 million pounds: PERILS

According to the review, about 16,000 properties in England were flooded during the three-month period of “remarkably persistent and exceptionally mild cyclonic” activity which, along with Storm Desmond, included the major storms of Abigail, Frank and Gertrude. More flooding occurred in January.

“At a national scale, the winter floods of 2015/16 were the most extreme on record,” said lead author Terry Marsh from the CEH. “The November to January period was the wettest three-month sequence in the U.K. rainfall series, which begins in 1910. Correspondingly, river flows across much of the country exceeded bankfull for extended periods. The associated flooding was both extensive and repetitive, and total river outflows from Great Britain following the passage of Storm Desmond in December exceeded the previous maximum by a substantial margin.”

The review highlights:

  • That December was the wettest and, on average, the warmest on record in the U.K., in records going back to 1910;
  • The highest ever recorded rainfall in the U.K. was measured when 341.4 millimetres of rain fell at Honister Pass in the Lake District in the 24 hours leading up to 6 p.m. on Dec. 5, 2015;
  • Record peak flows occurred at the rivers Eden, Tyne and Lune in England of around 1,700 cubic metres per second; and
  • Other record peak flows also took place on the rivers Nith, Tweed, Clyde, Forth and Tay in Scotland and the Mourne in Northern Ireland.

Related: Floods in U.K. expected to produce repair bill of £1.3 billion, good progress on repairs to date

Jamie Hannaford, a co-author of the report, said that the 2015/16 flooding follows the winter 2013/2014 flooding in southern England and other severe events of recent years, including the 2005 and 2009 floods in Cumbria. “Understandably, this leads to speculation that flood risk is increasing due to climate change,” Hannaford said in the release, noting that there are trends towards higher river flows over the last five decades, especially in western Britain. “But records are short and there is much natural year-to-year variability, which makes it hard to attribute observed trends to climate change,” Hannaford said. “Nevertheless, recent modelling studies do point towards human-induced warming having a role to play in these and other recent floods.”

Another co-author, Cumbrian resident Dr. Ed Henderson from the British Hydrological Society, added that “the effects of the floods are personal. Thousands of Cumbrians, like people in other flood-affected parts of the country, have seen their lives upturned. Many have experienced life-changing financial losses and incredible stress. Speaking with flood victims, the words that come out are despair, fear and anxiety – fear of flooding again and the anxiety of an approaching winter.”

Dr. Nick Reynard, the CEH’s science area lead for natural hazards research, said that “we are working hard with [the] central government to improve flood estimation, and examine how potential mitigation measures, such as natural flood management, can help us reduce the impact of flooding in future.”