POPULATIONS OUTRUNNING WATER SUPPLY
AS WORLD HITS 6 BILLION
Lester R. Brown and Brian Halweil
September 23,1999As world population approaches
6 billion on October 12, water tables are falling on every
continent, major rivers are drained dry before they reach
the sea and millions of people lack enough water to satisfy
Water tables are now falling in China, India, and the
United States, which together produce half the world's
food. Historically, irrigated farming has been plagued
with waterlogging, salting, and silting, but now, with
the advent of powerful diesel and electrically powered
pumps, it is also threatened by aquifer depletion.
In China, water tables are falling almost everywhere
that the land is flat. Under the North China Plain, the
country's breadbasket, water tables are falling by 1.5
meters, or roughly 5 feet, per year. Where wells have
gone dry, farmers have been forced either to drill deeper,
if they can afford it, or to abandon irrigated agriculture,
converting back to lower-yield rainfed farming.
In India, a country whose population hit 1 billion on
August 15, the pumping of underground water is now estimated
to be double the rate of aquifer recharge from rainfall.
The International Water Management Institute, the world's
premier water research group, estimates that India's grain
harvest could be reduced by up to one fourth as a result
of aquifer depletion. In a country adding 18 million people
per year, this is not good news.
Third in a series of reports on global population issues
leading up to the Day of 6 Billion, October 12, 1999.
Additional information and resources can be found at http://www.worldwatch.org/alerts/pop2.html.
In the southern Great Plains of the United States, depletion
of the Ogallala aquifer has already led to irrigation
cutbacks. Texas, Oklahoma, Kansas, and Colorado have been
losing irrigated land over the last two decades. Texas,
for example, has lost irrigated land at roughly one percent
per year since 1980.
Rivers running dry provide an even more visible manifestation
of water shortages as growing populations take more water.
The Yellow River, the cradle of Chinese civilization,
first ran dry in 1972. Since 1985, it has run dry for
part of each year. In 1997, it failed to reach the sea
during 226 days, or roughly 7 months of the year.
During the dry season, the Ganges River has little water
left when it reaches the Bay of Bengal. India, with more
than a billion people taking the lion's share of the water,
is leaving too little for the farmers of Bangladesh during
the dry season.
In central Asia, the Amu Darya, one of two rivers that
once fed the Aral Sea, is now drained dry by farmers in
Turkmenistan and Uzbekistan. As the Sea has shrunk to
scarcely half its original size, the rising salt concentration
has destroyed all fish, eliminating a rich fishery that
once landed 100 million pounds of fish per year.
Similarly, the Colorado, the major river in the southwestern
United States, rarely ever makes it to the Gulf of California.
The fishery at its mouth that once supported several thousand
Cocopa Indians has now disappeared. Today the Nile, like
many other major rivers, has little water left when it
reaches the sea. Even though virtually all the water in
the river is now claimed, the population of the three
principal basin countries-Egypt, the Sudan, and Ethiopia,
where most of the water originates-is projected to increase
from 153 million today to 343 million in 2050, generating
intense competition for water.
Hydrologists estimate that when the amount of fresh
water per person in a country drops below 1,700 cubic
meters per year the country is facing water stress. In
her new book, Pillar
of Sand: Can the Irrigation Miracle Last, Worldwatch
senior fellow Sandra Postel reports that the number of
people living in countries experiencing water stress will
increase from 467 million in 1995 to over 3 billion by
2025 as population continues to grow. In effect, these
people will not have enough water to produce food and
satisfy residential and other needs.
Postel estimates the current world water deficit ¾ the
excess of water pumping over recharge from rainfall ¾
at 160 billion tons per year. Since it takes 1,000 tons
of water to produce 1 ton of grain, this water deficit
is equal to 160 million tons of grain, a quantity only
slightly less than annual world grain exports of 200 million
Ironically, the excessive grain supplies that have depressed
world grain prices in 1999 are partly the result of overpumping.
If falling water tables were stabilized by a cutback in
pumping, the resulting decline in grain production would
likely drive prices off the top of the chart.
As water becomes scarce, the competition for water between
cities and countryside intensifies. In this competition,
farmers almost always lose. In North Africa and the Middle
East, the region ranging from Morocco in the west to Iran
in the east, virtually every country is experiencing water
shortages. As cities grow, countries take water from agriculture
to satisfy expanding urban water needs. The countries
then import grain to offset the water losses.
Given that importing one ton of grain is equal to importing
1,000 tons of water, this is the most efficient way for
water-short countries to import water. Last year the water
required to produce the grain and other farm products
imported into this region was roughly equal to the annual
flow of the Nile River. With more and more countries looking
to the world market for food, spreading water scarcity
may soon translate into world food scarcity.
It is often said that the competition for water among
countries may take the form of military conflict. But
it now seems more likely that the competition for water
will take place in world grain markets. It is the countries
that are financially strongest, not those that are militarily
the strongest, that are likely to win in this competition.
If the world could move from the U.N. medium population
projection of nearly 9 billion in 2050 to the low projection
of less than 7 billion, water stresses would be greatly
alleviated, making the water problem much more manageable.
If the world stays on the current population trajectory,
a growing share of humanity may simply lack the water
needed for a decent life.
R. BROWN is president and BRIAN
HALWEIL is staff researcher at Worldwatch Institute,
a Washington, D.C.-based research organization.
Visit Worldwatch's web
page on population to learn more about the Institute's
population publications and links to other population
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Worldwatch News Brief 99-9