Southern England needs twice as much rainfall over the summer than normal to get back to expected levels, climate scientists have calculated.
As water companies prepare to enforce a hosepipe ban across the south of England from 5 April, researchers at the University of Reading said that the region needed rainfall equivalent to the amount seen during the 2007 summer floods to get back to normal.
Dr. Ben Lloyd-Hughes, from the University's Walker Institute, said: "Over the last two years we've seen 22 months with normal or below normal rainfall, and crucially we've seen two dry winters in a row.
"We've seen less rainfall over the last year than in the 1976 drought and for the south east we have to go back to 1921 to see such a severe and prolonged lack of rainfall.
"The lack of rainfall over the last year means that we would need over 400mm of rain to get us back to normal levels by August - that's more than twice what we would normally get over the April to July period.
"We have seen those sorts of rainfall amounts before though. For those of you who remember the summer of 2007 when flooding threatened the Tewksbury electricity sub-station, we saw more than double the normal amount of rainfall in May, June and July."
He added that Met Office forecasts hinted at the possibility of some relief, with showers predicted over the next few weeks in the south of England, but the Met Office experimental forecasts, which look 2-4 months into the future, suggest normal or even drier than normal conditions are most likely over the next few months.
Dr. Lloyd-Hughes said that unlike in 1976, current drought conditions were only affecting the southern part of the UK.
He said: "What we've got is a situation with very dry soils and low river and aquifer levels. At this time of year, winter rains have usually replenished water supplies and soils are wet. So to see such dry conditions at the beginning of the spring/summer season is a real concern to water companies and farmers."
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