– 2015-07-07 21:24:51
NASA Data Shows Global Groundwater Depletion
Renee Lewis / Al Jazeera America
(June 16, 2015) — In over half of the world’s largest aquifers, water is being drawn faster than it is being replenished, while some of those wellsprings may be much smaller than previously assumed, according to two studies released on Tuesday.
As climate change and population growth increasingly stress the world’s water supplies, understanding how much groundwater exists and at what rates it can be sustainably drawn is critical, said scientists behind the studies.
“Until improved storage estimates exist to determine a system’s full capacity to buffer against renewable ground water stress, continued pressure on aquifer systems could lead to irreversible depletion that seriously threaten the sustainability of groundwater dependent regions,” said a University of California at Irvine report titled “Uncertainty in Global Groundwater Storage.”
Although surface water is the world’s main freshwater supply, it has become less reliable and predictable. Groundwater is becoming an increasingly important source, with some 2 billion people depending on it, said researchers behind a second study, also by UC Irvine.
“Understanding the amount of groundwater used versus the volume available is crucial,” said the second report, titled “Quantifying Renewable Groundwater Stress.”
It is critical to understand how human and natural dynamics are impacting the world’s available water resources in order to determine levels of sustainable use, the second study said.
The first report found that there is great uncertainty in the total groundwater storage and estimates of depletion, which is becoming increasingly relevant in regions prone to drought.
From satellite observations using NASA’s Gravity Recovery and Climate Experiment (GRACE) mission, researchers found that some aquifers were much smaller than previously thought.
Groundwater aquifers take thousands of years to be replenished, so unsustainable use could make access to freshwater impossible in regions that do not have correct data on supply versus use, the first report said.
The second report found that the use of 21 of the world’s 37 largest aquifers has become unsustainable, meaning more water is being drawn than replenished. Among the aquifers with the least sustainable use were two in India, one in China, and California’s Central Valley aquifer, the report said.
Researchers characterized the Central Valley aquifer as “highly stressed” because due it use for irrigation and the drought that has gripped the state.
“The current depletion rate shows that the aquifer is unable to balance the combined impact of groundwater use and drought,” the report said.
Such information is crucial for leaders to govern groundwater resources sustainably and to ensure active management of those aquifers, scientists said. Lacking such information, but responding to stress put on groundwater from the drought, California lawmakers passed the first regulations to govern the resource in 2014. Unfortunately, the report added, the laws may not go into effect until 2040.
Three aquifers in the middle of the United States were being drawn from in a sustainable manner, the second report said. But it warned that the Atlantic and Gulf Coastal Plains aquifer under Florida and the Gulf Coast was being depleted.
The author of the two studies, Jay Famiglietti, a senior water scientist at NASA’s Jet Propulsion Laboratory and the principle investigator for the studies, said the water table is dropping throughout the world, according to the Washington Post.
“We need to get our heads together on how we manage groundwater — because we’re running out of it,” Famiglietti told the Post.
UN: World Could Face 40 Percent Water Shortfall by 2030
Al Jazeera America
(March 20, 2015) — The world could suffer a 40 percent shortfall in water in just 15 years unless countries dramatically change their use of the resource, a United Nations report warned Friday.
Many underground water reserves are already running low, while rainfall patterns are predicted to become more erratic with climate change. As the world’s population grows to an expected 9 billion by 2050, more groundwater will be needed for farming, industry and personal consumption.
With “business as usual” the world is facing a “collapse in our global socioeconomic system,” Richard Connor, lead author of the report, told Reuters.
The report predicts global water demand will increase 55 percent by 2050, while reserves dwindle. If current usage trends don’t change, the world will have only 60 percent of the water it needs in 2030, it said.
Having less available water risks catastrophe on many fronts: crops could fail, ecosystems could break down, industries could collapse, disease and poverty could worsen, and violent conflicts over access to water could become more frequent.
“Unless the balance between demand and finite supplies is restored, the world will face an increasingly severe global water deficit,” the annual World Water Development Report said, noting that more efficient use could guarantee enough supply in the future.
By 2050 two thirds of the world’s population will be living in cities, and demand for water is expected to grow related to urbanization in developing countries. Urbanization means that access to safe water and adequate sanitation, although typically higher in cities, has decreased in the fastest growing urban areas.
One example is sub-Saharan Africa, where urbanization — often unplanned — is happening most rapidly. Here the proportion of people who have piped water on their premises has fallen to 34 percent from 42 percent since 1990.
“The spontaneous urbanization, which creates slums, makes it very difficult because of the layout of the slums to provide water,” Joan Clos, executive director of the United Nations Human Settlements Program (UN-HABITAT), told Reuters.
The report, released in New Delhi two days before World Water Day, calls on policymakers and communities to rethink water policies, urging more conservation as well as recycling of wastewater as is done in Singapore. Countries may also want to consider raising prices for water, as well as searching for ways to make water-intensive sectors more efficient and less polluting, it said.
In many countries including India, water use is largely unregulated and often wasteful. Pollution of water is often ignored and unpunished. At least 80 percent of India’s population relies on groundwater for drinking to avoid bacteria-infested surface waters.
In agriculture-intense India, where studies show some aquifers are being depleted at the world’s fastest rates, the shortfall has been forecast at 50 percent or even higher. Climate change is expected to make the situation worse, as higher temperatures and more erratic weather patterns could disrupt rainfall.
Currently, about 748 million people worldwide have poor access to clean drinking water, the report said, cautioning that economic growth alone is not the solution — and could make the situation worse unless reforms ensure more efficiency and less pollution.
“Unsustainable development pathways and governance failures have affected the quality and availability of water resources, compromising their capacity to generate social and economic benefits,” it said. “Economic growth itself is not a guarantee for wider social progress.”
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