Floods in 2009 and 2015 were worst in Cumbria for centuries – study

cockermouth, cumbria in november 2009
Cockermouth, Cumbria in November 2009. Analysis shows the floods were unprecedented in key respects. Photograph: Ashley Cooper/Barcroftmedia

Analysis in north-west England linked to evidence of UK’s vulnerability to climate crisis

— The floods of 2009 and 2015 in north-west England were the worst for more than 550 years, according to groundbreaking analysis of lake sediment in the region.

Residents have long suspected that the devastating floods were the worst in living memory, but this confirmation – from an analysis of lake sediment layers – provides a unique window on to the history of flooding in one of the wettest parts of England, and reveals the global climate crisis.

Floods in the region in 2009 and 2015 – the latter the result of Storm Desmond – grabbed the headlines at the time, but are increasingly being linked to evidence of the UK’s vulnerability to the climate emergency. The new analysis shows that the most recent floods were unprecedented in key respects.

In 2015, more than 50,000 homes in Cumbria were flooded or had severe impacts from flooding. While the loss of life was relatively small, the damage to local people is still being felt in many areas. Similarly, floods in 2009 left thousands of people displaced from their homes, which took years to be resolved.

Richard Chiverrell, a professor of physical geography at the University of Liverpool, and the lead scientist conducting the research, said: “The convergence of information suggests a link with a warmer world and recent extreme flooding is likely.”

He said factors such as the way land is managed and changing farming practices were likely to have only a small effect, compared with the overriding force of changing weather.

He added: “The unprecedented nature of the recent phase of extreme floods accords with statements from the Environment Agency that climate changes and associated impacts on the frequency and magnitude of extreme events are one of the greatest challenges facing our society.”

This is believed to be the first time such an analysis has been used to gauge recent flooding against historic norms in the UK, and the same technique could be used elsewhere to form a wider picture of flooding in Britain in recent years.

The researchers studied Bassenthwaite Lake in Cumbria, where each flooding event leaves a distinct layer of sediment at the bottom. Flooding leaves much coarser sediment than normal deposits, because it washes in large amounts of material from the surrounding hills and streams. That left researchers with a much easier task in sorting out which layers came from particular events.

In their paper, published in the journal Earth Surface Processes and Landforms, the team of researchers led by the universities of Liverpool and Southampton compared the evidence of lake sediment from the floods of 2009 and 2015 with the 558-year record from the sediment at the bottom of the Bassenthwaite lake.

David Sear, a professor at the University of Southampton, said: “For the first time, we have been able to take sedimentary records from lake beds and convert them into the kind of data used by flood risk managers. These are the events that cause most damage and cost to society, so improving our ability to estimate their chance of occurring is important.”


by Fiona Harvey | The Guardian

 

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