Heaviest rainfall in decade poses no problem for Hampstead Heath’s dams

The water levels remained low at the men's pond this week. Picture: Polly Hancock

The water levels remained low at the men's pond this week. Picture: Polly Hancock - Credit: Archant

Hampstead was the wettest place in the country as it suffered a record-breaking drenching this week – but the deluge failed to trouble the Heath’s much-discussed dams.

Monday witnessed the largest downpour in a single day since 2002 according to Met Office logs for the Hampstead weather station at Whitestone Pond.

The station on the edge of the Heath recorded 57mm of rainfall – the heaviest in the UK on Monday and nearly three-quarters of Hampstead’s average total for October.

Yet the downpour posed no challenge to the ponds as water levels stayed so low they did not even trigger an automatic alarm system.

The news has been seized upon by critics of the City of London Corporation’s plans to make drastic changes to the ponds and their dams to prevent a killer flood.

Eve Featherstone, 59, a member of the Kenwood Ladies’ Pond Association, said: “We had the heaviest rain in the whole country and it didn’t even trigger their warning system – it shows that these dam works are completely unnecessary.”

The 24-hour rainfall surpassed that of May 2010, when 51mm fell and two ponds overtopped.

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A spokesman for the City, which manages the Heath, said the ponds coped so well because this downpour followed a dry period, so the water level was low to begin with.

It came just weeks before the battle over the ponds hits the High Court. The Heath and Hampstead Society mounts its judicial review challenge on November 13.

Society chairman Marc Hutchinson said: “One of the themes of our case is that the City and its advisers have exaggerated the risk of overtopping and collapse and largely ignored the 300-year record of the ponds not being the cause of flooding.

“We have just had the heaviest rainfall on the Heath since 2002 and the ponds look just as they did before the downpour.”

Since 1970, there have only been four greater 24-hour rainfalls recorded by the Met Office in Hampstead, including the famous flood of August 1975 when 170.8mm came down in a day.

The others were in 2002, 1992 and 1977, the latter being the second heaviest after 1975 with 79.6mm. Monday’s rain was the heaviest on record for October.

A spokesman for the City of London Corporation said: “The rainfall earlier this week was not a serious storm and followed a period of relatively dry weather so the ponds were at a low level.

“In 2010, the rainfall happened over a shorter duration which put more strain on the ponds overflow capacity.”