Briefly stated, not only is the Colorado River itself being sucked dry, but also being pumped dry are the underground aquifers that help to maintain the flow of the Colorado River and all of its tributaries.
Satellite Study Reveals Parched U.S. West Using Up Underground Water
July 24, 2014
RELEASE 14-200 by NASA.gov
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.
A new study by NASA and University of California, Irvine, scientists finds more than 75 percent of the water loss in the drought-stricken Colorado River Basin since late 2004 came from underground resources. The extent of groundwater [underground aquifers] loss may pose a greater threat to the water supply of the western United States than previously thought. [Lead authors of this study are: Stephanie Castle and Jay Famiglietti ]
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.
The research team used data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite mission to track changes in the mass of the Colorado River Basin, which are related to changes in water amount on and below the surface. 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.
“We don’t know exactly how much groundwater we have left, so we don’t know when we’re going to run out,” said Stephanie Castle, a water resources specialist at the University of California, Irvine, and the study’s lead author. “This is a lot of water to lose. We thought that the picture could be pretty bad, but this was shocking.”
Water above ground in the basin’s rivers and lakes is managed by the U.S. Bureau of Reclamation, and its losses are documented. Pumping from underground aquifers is regulated by individual states and is often not well documented.
“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 [NASA’s Jet Propulsion Laboratory] 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.”
Famiglietti said GRACE is like having a giant scale in the sky. Within a given region, the change in mass due to rising or falling water reserves influences the strength of the local gravitational attraction. By periodically measuring gravity regionally, GRACE reveals how much a region’s water storage changes over time.
The Colorado River is the only major river in the southwestern United States. Its basin supplies water to about 40 million people in seven states, as well as irrigating roughly four million acres of farmland.
“The Colorado River Basin is the water lifeline of the western United States,” said Famiglietti. “With Lake Mead at its lowest level ever, we wanted to explore whether the basin, like most other regions around the world, was relying on groundwater to make up for the limited surface-water supply. We found a surprisingly high and long-term reliance on groundwater to bridge the gap between supply and demand.”
Famiglietti noted that the rapid depletion rate will compound the problem of short supply by leading to further declines in streamflow in the Colorado River.
“Combined with declining snowpack and population growth, this will likely threaten the long-term ability of the basin to meet its water allocation commitments to the seven basin states and to Mexico,” Famiglietti said.
The study has been accepted for publication in the journal Geophysical Research Letters, which posted the manuscript online Thursday, July 24, 2014. Coauthors included other scientists from NASA’s Goddard Space Flight Center, Greenbelt, Maryland, and the National Center for Atmospheric Research, Boulder, Colorado. The research was funded by NASA and the University of California, Irvine.
Droughts In California, US Southwest Help Drain 17 Trillion Gallons Of Water From Colorado River Basin In Last Decade
International Business Times www.IBTimes.com
Lake Mead water levels are reaching historic lows amid widespread drought conditions in the Colorado River Basin.
The Colorado River basin has lost 17 trillion gallons of water in the past decade due to drought and ever-rising demand, according to data gathered from NASA satellites. The disappearance threatens to jeopardize the long-term water supplies of the seven U.S. states and parts of Mexico served by the basin, researchers said.
The study, released Thursday [July 24, 2014] by NASA and the University of California at Irvine, is the first to quantify how much groundwater people in the Southwest are using during the region’s current drought, the Associated Press reported.
“This is a lot of water to lose. We thought that the picture could be pretty bad, but this was shocking,” Stephanie Castle, the study’s lead author and a water resource specialist at UC Irvine, said in a statement.
Unlike the water in the rivers and lakes, whose levels are tracked and managed by the U.S. Bureau of Reclamation, underground water supplies are poorly documented and ill-managed, so it’s difficult for scientists to know how much of the water is still available. “We don’t know exactly how much groundwater we have left, so we don’t know when we’re going to run out,” Castle said.
Using NASA satellites, the researchers found that since 2004, the Colorado River basin has lost 53 million acre feet, or 17 trillion gallons, of water. That’s nearly twice the volume of Nevada’s Lake Mead — the nation’s largest reservoir — and is enough to supply more than 50 million households with water for a year. More than 75 percent of the total water losses was from groundwater, the study said.
While above-ground water sources can be replenished by rainfall, groundwater sources [underground aquifers] can become so depleted that they may never refill, Castle told the AP. In Southwestern states, the loss of groundwater is emptying the reserves that protect farmers, consumers and ecosystems during prolonged periods of drought.
The Colorado River basin — the largest in the Southwest — supplies water to about 40 million people in California, Arizona, Colorado, New Mexico, Nevada, Utah and Wyoming, as well as to people in Mexico. The basin, which irrigates about four million acres of farmland on both sides of the border, “is the water lifeline of the western United States,” Jay Famiglietti, the study’s co-author and a senior water cycle scientist at NASA’s Jet Propulsion Lab, said in a statement.
The Colorado River Basin is drying up. It supplies water to about 40 million people in seven states. Major cities outside the basin also use water from the Colorado River. See MAP above provided bythe U.S. Bureau of Reclamation
Yet since 2000, the basin has suffered from prolonged and severe drought and has experienced the driest 14-year period in the past hundred years, according to the U.S. Bureau of Reclamation. Lake Mead water levels reached historic lows this month, dropping to levels not seen since the construction of the Hoover Dam in the 1930s.
California in particular is in the grip of a crippling three-year-long drought that researchers said could cost the state’s economy $2.2 billion this year, mainly from lost crop revenues and declining values of livestock and dairy.
Scientists are generally reluctant to peg specific weather and climate events to global warming, which is caused by the massive release of human-made greenhouse gas emissions. Over the long term, however, they agree that California and other arid regions will likely experience longer and more severe droughts in the coming decades because of global warming, which will threaten groundwater sustainability.
In the Southeast, “Climate change poses challenges for an already parched region that is expected to get hotter and, in its southern half, significantly drier,” according to the National Climate Assessment, a U.S. government report. “Severe and sustained drought will stress water sources, already over-utilized in many areas, forcing competition among farmers, energy producers, urban dwellers and plant and animal life for the region’s most precious resource.”
Famiglietti of NASA said that in the future, declining snowpack and population growth in the region could threaten the basin’s long-term ability to meet its water allocation commitments to the seven U.S. states and Mexico. “The extent of groundwater loss may pose a greater threat to the water supply of the western United States than previously thought,” he said.
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