Bone-dry California crying out for some of that Irish water

California is bone dry - and getting even drier as a three-year drought continues.

Its water deficit now stands at some 42 cubic km - the volume of water that would be needed to replenish depleted rivers and recharge underground aquifers.

To put that in a soggy Irish context, a 5cm rainfall over the island of Ireland would dump about 4.2 cubic km on us, a tenth of what is needed to reverse the water losses in California.

It would take half of all the rain that falls on Ireland in a year to make up California’s deficit.

Croke Park, by the way, would be nowhere near big enough to hold even a half of a cubic km of water.

The US calculation comes from the National Aeronautics and Space Administration, with Nasa scientists presenting their findings on Wednesday at the American Geophysical Union meeting in San Francisco.

This is the first time scientists have used satellite data in this way from Nasa’s Gravity Recovery and Climate (Grace) experiment satellites and from its Airborne Snow Observatory to measure water depletion levels.

Double trouble

California has double trouble, given the lack of rainfall and the reduced springtime deluge that usually comes as snow begins to melt on the Sierra Nevada mountain range.

Researchers found the state’s Sacramento and San Joaquin river basins were 42 cubic km below normal seasonal levels.

The water in these basins has fallen by 15 cubic km a year since 2011, which is more water than would be used each year by the state’s 38 million residents.

The snow melt will be less help than usual, the scientists say. Early data for 2014 suggests the snowpack in the mountains is only half of previous estimates.

Snow levels were one of the three lowest on record and the worst since 1977, the snow observatory said.

"It takes years to get into a drought of this severity, and it will likely take many more big storms and years to crawl out of it," said Jay Famiglietti of Nasa's Jet Propulsion Laboratory in Pasadena, who leads the research team.