An international collaboration of researchers warns that too many of the underground water resources in the United States are currently being overexploited, with potentially dangerous consequences for the country's food security. In addition, removing groundwater also leads to sea level rise.
The investigation was led by Bridget Scanlon, who holds an appointment as a senior research scientist with the University of Texas in Austin (UTA) Bureau of Economic Geology. She worked with colleagues at the United States Geological Survey (USGS) and the Université de Rennes in France.
Details of the new research effort were published in the latest issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS). The work was primarily focused on aquifers, sponge-like water reservoirs that are the source of springs and groundwater.
What experts show in this paper is that these aquifers are exploited too intensely, primarily through water extraction. Water is taken out so quickly, and in such high amounts, that the formation is not allowed to replenish its reserves.
While this may not be that bad in itself, the issue is that the water-depleted ground tends to become more compact, filling in the place once occupied by water with dirt. This causes aquifers to lose their sponginess, and become unable to hold more than a fraction of the water amounts they once did.
Another negative effect is that all of the water extracted from the ground eventually makes its way into the atmosphere and Earth's oceans, contributing to sea level rise. This phenomenon, which is promoted by global warming, currently threatens more than 4 million US citizens.
What the new research uncovered was that rapid groundwater depletion might lead to food insecurity in the country, primarily because not enough of the liquid will be left for agricultural applications. The study covers Central Valley, in California and the High Plains of the central US.
“We're already seeing changes in both areas. We're seeing decreases in rural populations in the High Plains. Increasing urbanization is replacing farms in the Central Valley,” Scanlon explains.
“And during droughts some farmers are forced to fallow their land. These trends will only accelerate as water scarcity issues become more severe,” adds the expert, who was also the lead author of the PNAS paper.
While the water scarcity issues currently plaguing California can be addressed to some extent, “irrigated agriculture in much of the southern High Plains is unsustainable,” Scanlon concludes, quoted by LiveScience