Nasa California Satellite Images Reveal Worst Drought in State's History

Nasa images have revealed the extent of the Californian drought. The images, taken from an altitude of 100,000ft, reveal how little snow the Sierra Nevada has seen this year, despite extensive rain and snow across the rest of the US.

Scientists plan to use the photographs, taken within the Earth's atmosphere, to help California monitor one of the worst droughts in its recorded history.

The California Department of Water Resources will work with Nasa to use data from aircraft mapping tools. The technology will measure the volume of water stored in the California snowpack and groundwater levels.

Nasa got involved after the dry year of 2009, when officials needed to address problems brought by the lack of rain and snow, such as sinking land.

In January, state governor Jerry Brown declared an emergency because of the drought and has called on state officials to prepare for water shortages.

Tom Farr, a Nasa geologist, said: "We're on the verge of being able to put all of these different kinds of instruments together, these measurements together, and start looking at the concept of perhaps closing the water budget of California."

Officials hope to use the data to track the expanse of fallow agricultural land in the Central Valley to accurately assess the impact of the dry spell.

Researchers said a satellite mapping system would also be used to gauge the extent of land subsidence and decreasing groundwater levels. A project has already analysed areas of subsidence in the San Joaquin Valley from 2007-11, caused by decreased groundwater levels.

Images from Nasa satellites that measure precipitation and soil moisture levels, which are due to launch this year, will also be pressed into service. The Soil Moisture Active Passive (SMAP) will launch in November, to inform water resource management decisions on water availability.

The information is expected to help state officials plan for year-round water supplies as well as detecting damage caused by groundwater pumping.

Officials alerted Californian farmers that drastic cutbacks in irrigation water were expected to render half a million acres of cropland unusable this year. That could cost the state billions of dollars.