Foreshadows Larger Water Threat
This year, much of the eastern United States is suffering
through the third worst drought of the century. If these
conditions persist into the fall and winter, scientists
say it could surpass in severity the devastating droughts
of 1929 and 1966.
Authorities in seven states and the District of Columbia
have issued drought advisories, warnings, or emergencies.
Throughout the mid-Atlantic region, more than three-quarters
of all streams and rivers(including the Delaware, Susquehanna,
and Potomac(have hit record or near-record low flows.
Rising salinity and low oxygen levels have caused massive
fish kills, including one numbering 200,000 in Maryland
waterways. In late July, a salt front moving up the Hudson
River was just 6 miles downstream of the water supply
intake for the city of Poughkeepsie, New York.
In the worst-hit areas, wells have run dry, causing
owners to drill deeper in a frantic search for water.
Corn crops have withered under searing heat and rainless
skies. Maryland has had the driest growing season since
record-keeping began a century ago.
At the moment, stricken regions can take solace in the
knowledge that droughts eventually come to an end. But
a much larger, long-term water threat is going virtually
unnoticed even as it builds to staggering proportions:
Water supplies are running short in several of the world's
major food-producing regions, even as global food needs
continue to climb.
Water tables are falling from the overpumping of groundwater
in the breadbaskets and rice bowls of central and northern
China, northwest India, parts of Pakistan, much of the
United States, North Africa, the Middle East, and the
Arabian Peninsula. Farmers in these regions are pumping
groundwater faster than nature is replenishing it. Just
as a bank account dwindles if withdrawals routinely exceed
deposits, so will an underground water reserve decline
if extractions exceed replenishment.
During the last three decades, as farmers sunk millions
of wells, the depletion of underground aquifers has spread
from isolated pockets of the agricultural landscape to
large portions of irrigated land. In India, a government-commissioned
study found that "overexploitation of ground water resources
is widespread across the country." As much as a quarter
of India's grain production could be at risk as a result
of ground water depletion.
Likewise, overpumping is widespread in China's north-central
plain, which produces some 40 percent of the nation's
grain. Across a wide area, water tables have been dropping
1 to 1.5 meters a year, even as the nation's water demands
continue to climb.
In the United States, one-fifth of all irrigated land
gets water from a vast underground reserve known as the
Ogallala. One of the planet's greatest aquifers, it spans
portions of eight states, from South Dakota in the north
to Texas in the south. In its southern reaches, the Ogallala
gets very little replenishment from rainfall and decades
of heavy pumping have taken a toll. The volume of water
depleted to date is equal to the annual flow of 18 Colorado
All told, the world's farmers are racking up an annual
water deficit of some 160 billion cubic meters-the amount
used to produce nearly 10 percent of the world's grain.
The overpumping of groundwater cannot continue indefinitely.
Eventually, the wells run dry, or it becomes too expensive
to pump from greater depths.
Even if groundwater depletion was the only water problem
in our farming regions, we would have ample cause for
concern; but it is not. Many major rivers now run dry
for large portions of the year-including the Yellow in
China, the Indus in Pakistan, the Ganges in South Asia,
and the Colorado in the American Southwest. Worldwide,
one in five acres of irrigated land is damaged by a buildup
of salt that is slowly sapping the soil's fertility. Cities
and farms now compete for scarce water, as do neighboring
countries that depend on the same river.
Meanwhile, populations continue to grow fastest in some
of the world's most water-short regions. The number of
people living in water-stressed countries is projected
to climb from 470 million to 3 billion by 2025. With this
number of people living in countries lacking enough water
to be food self-sufficient, competition for grain imports
will increase. Whether the United States, Europe, and
other exporters will produce sufficient surpluses to meet
those import demands is only half the issue. The other
half is whether the exports will be offered at a price
that poor, food-importing nations-especially those in
South Asia and sub-Saharan Africa-can afford.
Hanging over these worsening water problems is the prospect
of climate change. One likely effect of higher temperatures
and more rapid melting of winter snowpacks is a reduction
in available water supplies during the summer months,
when farms and cities need water most. In addition, for
some period of time, our reservoirs and water systems
will be poorly matched to altered rainfall and river flow
patterns(creating additional vulnerabilities in our water
and food systems.
Water scarcity is now the single biggest threat to global
food production. Only by taking action now to conserve
the water supplies in our major crop-producing regions
can we secure enough water to satisfy future food needs.
POSTEL is author of Pillar
of Sand: Can the Irrigation Miracle Last? (W.W.
Norton, 1999). She directs the Global Water Policy Project
in Amherst, Massachusetts, and is a Senior Fellow of Worldwatch
current issue of World Watch magazine contains
an article by Sandra Postel on water shortages that is
available as a free PDF file.
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Worldwatch News Brief 99-7