Satellites show world is running out of water - new NASA study
A joint study conducted by scientists from NASA and the University of California has revealed that the world’s water reserve levels have become dangerously low.
The main reason is humanity’s constantly growing demand for water.
The researchers have concluded that “significant segments of Earth’s population are consuming groundwater quickly without knowing when it might run out.”
The research findings were published in the Water Resources Research journal on Tuesday.
The scientists used NASA’s twin Gravity Recovery and Climate Experiment (GRACE) satellites between 2003 and 2013 to take precise measurements of the world’s groundwater reservoirs, yielding the most detailed view of the planet’s underground water reserves to date. The GRACE satellites detected changes in the Earth’s gravitational pull, as large volumes of water under the ground create stronger gravitation.
“This has really been our first chance to see how these large reservoirs change over time,” said Gordon Grant, a research hydrologist at Oregon State University, who was a member of the research team.
The study has showed that about one third of Earth’s largest groundwater basins – 13 of the planet’s 37 – are being rapidly depleted while receiving little to no recharge.
“Given how quickly we are consuming the world’s groundwater reserves, we need a coordinated global effort to determine how much is left,”said UCI professor and principal investigator Jay Famiglietti, who is also the senior water scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Underground aquifers supply up to 35 percent of the water used by humans worldwide, being the primary source of freshwater for approximately two billion people, according to the study.
Natural cataclysms such as drought can increase that demand.
“As we’re seeing in California right now, we rely much more heavily on groundwater during drought,” said Famiglietti. “When examining the sustainability of a region’s water resources, we absolutely must account for that dependence.”
The extremely stressed aquifers are situated in relatively poor, densely populated areas, such as northwest India, Pakistan, and North Africa, where there are almost no alternatives to underground water supplies.
The world’s most stressed aquifer, which is being rapidly tapped with no recharge at all, is the Arabian Aquifer which supplies water for more than 60 million people, followed by the Indus Basin in India and Pakistan, and the Murzuk-Djado Basin in Libya and Niger.
Global warming is making the regions near the equator drier, leading to a situation where people have to tap more water from aquifers to solve the issue of water scarcity.
Most of the groundwater used for human consumption does not go back down to aquifers, but evaporates or is dumped into the rivers along with production and utilization wastes, eventually ending up in ocean.
The scientists emphasize that water-insensitive industrial activities put serious strain on the health of aquifers, leading to their rapid depletion. In the Australian Canning Basin, for example, less than 1 percent of the aquifer is covered by residential areas, yet it ranks third in rate of depletion according to the GRACE research. Scientists suspect the rapid exhaustion of reserves may be due to mining activities in the area.
Alexandra Richey, the research project’s leading scientist, said the team has tried to warn the international community and call for active management of water resources today, in order to protect the future.
“We don’t actually know how much is stored in each of these aquifers. Estimates of remaining storage might vary from decades to millennia,” said Richey. “In a water-scarce society, we can no longer tolerate this level of uncertainty, especially since groundwater is disappearing so rapidly.”
A 2012 Japanese study suggested that up to 40 percent of the sea-level rise observed in the last ten years can be accounted for by groundwater flushed into the ocean after human use.