US: A new study by NASA and University of California, Irvine, scientists has found that more than 75% of the water loss in the drought-stricken Colorado River Basin since late 2004 came from underground resources. The extent of groundwater loss may pose a greater threat to the water supply of the western United States than previously thought.
For the research, data from Gravity Recovery and Climate Experiment (GRACE) satellite mission was used to track changes in the mass of the Colorado River Basin, which are related to changes in water amount on and below the surface.
GRACE is a joint mission with the German Aerospace Centre and the German Research Centre for Geosciences, in partnership with the University of Texas at Austin. NASA Jet Propulsion Laboratory (NASA JPL) developed the GRACE spacecraft and manages the mission for NASA's Science Mission Directorate, Washington.
|The Colorado River Basin lost nearly 53 million acre feet of freshwater over the past nine years, according to a new study based on data from NASA’s GRACE mission. This is almost double the volume of the nation's largest reservoir, Nevada's Lake Mead (pictured). Image Credit: U.S. Bureau of Reclamation.|
Monthly measurements of the change in water mass from December 2004 to November 2013 revealed the basin lost nearly 53 million acre feet (65 cubic kilometers) of freshwater; almost double the volume of the nation's largest reservoir, Nevada's Lake Mead. More than three-quarters of the total — about 41 million acre feet (50 cubic kilometers) — was from groundwater.
This study is the first to quantify the amount that groundwater contributes to the water needs of western states. According to the U.S. Bureau of Reclamation, the federal water management agency, the basin has been suffering from prolonged, severe drought since 2000 and has experienced the driest 14-year period in the last hundred years.
“There's only one way to put together a very large-area study like this, and that is with satellites,” said senior author Jay Famiglietti, senior water cycle scientist at JPL on leave from UC Irvine, where he is an Earth system science professor. “There's just not enough information available from well data to put together a consistent, basin-wide picture.”
He added, “By periodically measuring gravity regionally, GRACE reveals how much a region's water storage changes over time.”
The study has been accepted for publication in the journal Geophysical Research Letters. The research was funded by NASA and the University of California.