More ‘extreme’ rainfall for warmer Britain

Extreme rainfall that can lead to flooding have increased dramatically since the 1960s, and are likely to keep growing stronger and more frequent as the climate warms, a research study from the University of Newcastle has found.

Looking back over Britain’s rainfall records for the period 1961-2000, scientists found that sustained periods of rain have grown several times more frequent in Scotland and Northern England. They said that the 5m Britons living near rivers will suffer increased flooding, and called for flood management plans to be adapted accordingly.

In Scotland, continuous rain lasting 5-10 days was four times as likely in the 1990s as it had been over the previous 30 years, and in Northern England this type of event became twice as likely, the study found.

In South East England, 5-10 day-long rain actually became less likely over the same period, but closer analysis revealed that more shorter events were occurring, most of them in the autumn.

More sustained rainfall can therefore be expected in the future as temperatures rise, with the events likely to grow stronger, said Dr Hayley Fowler, who led the research.

As the changes in rainfall matched those simulated by climate models for the same period, the scientists see them as further evidence for climate change.

“The changes we observed over the 40-year period we studied are consistent with the trend we would expect from global warming,” she said.

“If the trend continues, which is likely, this suggests we will have an increase in flooding over the coming years which has major implications for flood risk management.”

Water companies should confront the double dilemma of increased floods and droughts by looking for ways of collecting rain during extreme rainfall events and store it for use during dry periods, she added.

“One solution could be to build storage facilities such as small reservoirs close to rivers to catch the excess water following extreme rainfall events,” said Dr Fowler, a researcher at Newcastle University’s school of civil engineering and geosciences.

“This could also help alleviate the potential for flooding as well as solve the water shortage crisis we are likely to experience in the summer months,” she said.

Dr Fowler’s team also found that the most extreme rainstorms, which only occurred twice a century pre-1990, can now be expected once every eight years in Eastern Scotland, once every 11 years in Southern Scotland, and once in 25 years in Northern Scotland and Northern England.

Dr Fowler will present the results of the study at the BA Festival of Science in Norwich this Wednesday.

Goska Romanowicz

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