Stark’s new satellite data reveal that the Colorado River Basin has lost large amounts of groundwater in recent decades, and some investigations suggest that this groundwater could be exhausted at the end of the century.
But is that really the case? And if so, what could be done to prevent that from happening?
While the groundwater is running out, it is unlikely that the water is completely exhausted. However, the continuous drainage of the basin could cause the water table to fall so far is basically inaccessible, said Live Science experts.
Mass basin
The Colorado River Serpentea through seven US states (Wyoming, Colorado, Utah, New Mexico, Nevada, Arizona and California) and two Mexican states (Baja California and Sonora). Some 40 million peopleIncluding those of Phoenix and Las Vegas, they depend on it for their water needs. But as the supplies of this superficial water have dried in the last two decades, reaching minimum registration – More and more people have been pumping groundwater from far below the surface, mainly for agricultural use.
To have a better idea of how much groundwater it is being extracted, Jay FamigliettiDirector of Sciences of the Arizona Water Innovation Initiative at Arizona State University, and his colleagues resorted to the data of NASA’s recovery and climate climate experiment (Grace) and Grace follow -up satellite missions. These satellites track changes in the field of gravity of the Earth to measure changes in the amount of water above and below the ground, and when combined with data on the snow layer, surface water and soil moisture, this information can allow scientists to estimate how much groundwater it has been exhausted.
Researchers estimate that since 2003, Wells pumping has drained around 28 million acres (34 cubic kilometers) of groundwater of the Colorado River basin. This is similar to the capacity of Lake Mead, the largest American deposit, which is behind the Hoover dam on the Colorado River. The study was published on May 27 in the magazine Geophysical Research Letters.
Around three quarters of the exhaustion of groundwater are occurring in the lower river basin, largely in Arizona, where water is pumped from desert aquifers to water cultivation lands, according to the study. In these areas largely rural, farms are generally not connected to municipal water systems and, instead, they trust the pumping water of the wells on the property. Because the wells are private, there is often no municipal measurement, at the county or state level of how much water they are writing.
Famiglietti and their colleagues estimate that annual groundwater losses in the basin averaged more than 1.2 million acres-pies (1.5 cubic kilometers) and if the trend continues, it could cause water shortage and limit food production.
“We are going through a critical point in which it is becoming increasingly expensive to deepen the aquifer, and water quality is decreasing,” said Famiglietti.
Dozen wells have dried In the area. Collapsent aquifers have caused the sinking of the Earthand Created fissures.
Bottom of the shape
Ryan MitchellChief of Hydrologist of the Department of Water Resources of Arizona, who did not participate in the new study, told Live Science that he welcomes the newspaper’s findings and is concerned with the levels of estimated exhaustion of groundwater in some areas. However, he disagrees with a prayer in the document that suggests that a simulation of the Arizona Water Resources Department indicated “complete exhaustion for the end of the century.” He said that simulations do not indicate a complete exhaustion of groundwater, much less for the end of the century.
The groundwater will not be exhausted, he said, but neither the satellite data of grace nor the measures of the use of water will tell us exactly how much water remains in the aquifers.
“It is almost as if it were an unknowable number in the same way as if someone said how many grains of sand there are on the beach, you could make some assumptions and make some conjectures, but you can never know the exact amount of sand grains,” Mitchell said.
Bridget ScanlonResearch professor at the Office of Economic Geology at the University of Texas in Austin, and his team recently used grace data to evaluate the Drought implications in the Colorado River Basin. They saw similar patterns, discovering that there was a period of high groundwater consumption as irrigation expanded between the 1940s and 1970s. Then, the amount of groundwater was recovered for a wet period in the early eighties and nineties.
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But since then, the image has deferred depending on how areas are handled. In “Active Management Areas“o Areas where water use is monitored, groundwater levels have remained approximately leveled. In these areas, groundwater is pumped, but according to how much it is elaborated, management agencies can divert more water to the exhausted area to filter the aquifer back.
In not administered areas, no agency tracks how much groundwater is pumped, so agencies do not know when to replace aquifers. High extraction in unm administrated areas is promoting the general drainage of groundwater, Mitchell told Live Science.
“We can’t handle what we don’t measure,” he said. “It shows that if you have established rules and monitor the use of water and actively handle it, you can keep it at a sustainable level.”
One thing is safe: wait for rainfall to end the drought and replace the aquifers will not be enough. Studies involve That the flow of the Colorado River is expected to continue decreasing thanks to the reductions linked to the climate in snowfall and rains, and that means that there will be less surface water to use, less water to recharge aquifers and more reasons to extract water from the underground.
The driest drilling is a solution, but there are problems with that, said Famiglietti. At some point, it will cost millions of dollars for a well deep enough that will have high energy costs to pump water, he said, and that water is likely to require treatment.
“As it advances in groundwater, that water has been in contact with the ground and rocks for a long time, so it is dissolving solids and salts,” said Famiglietti. This can cause water that is saltyBad taste or containing High levels of arsenic. “And because these are often filled by agricultural water, they [are] Collecting higher concentrations of pesticides and fertilizers, “said Famiglietti.
Another option is to reduce the use of water, for example, changing what is grown, to change Intensive water crops such as alfalfaFamiglietti said. “It can’t be a business as always,” he said. “We have to think about what our priorities are for the use of water.”
“I am so worried about tomorrow as I’m within about 100 years,” he said. “It is very clear that we need more groundwater management in the lower basin, which is mainly in Arizona. Only 18% per area is managed, and there is a lot of exhaustion that occurs outside those areas.”
All live experts spoke to suggest that extending the area covered by active water management areas would help, first, watching what is being used where and then trying to replace what is used.
As part of such schemes, water could be brought from another place, said Scanlon. For example, this happens when San Antonio buys water and vuele from East Texas to more than 150 miles (240 kilometers) away.
“Groundwater is a finite resource,” Mitchell said. “It must be able to let it be recharged naturally or be able to replenish what it uses. He said that Scanlon’s investigation shows that” we are fine in the areas of active management, and we are not making so much heat in the areas where we do not have any type of frame in its place. “
TO Legislative Law Project Extending the areas that are actively managed in Arizona, but the like they have stagnated after facing the opposition. Those opposites say that restricting water does not protect the existing agricultural use of groundwater and will suffocate economic growth. Some also oppose the use of water that is decided at the state level when they would prefer smaller water with directors chosen locally.
“We are not trying to spy on anyone; we just want to know what water is,” Mitchell said. “But it is difficult because confidence in governments is at its lowest point. [600 meters] Wells because it is too deep and too expensive. We want to try to help them protect their water resources. “
Editor’s note: This article was updated at 9.00 am et on June 16 to correct an appointment attributed to Bridget Scanlon instead of Ryan Mitchell.
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