MAKING EVERY DROP COUNT
Source:
Scientific American, Feb2001, Vol. 284 Issue 2, p40, 6p.
We drink it, we generate
electricity with it, we soak our crops with it. And we're stretching our
supplies to the breaking point. Will we have enough clean water
to. satisfy all the world's needs?
The history of human
civilization is entwined with the history of the ways we have learned to
manipulate water resources. The earliest agricultural
communities emerged where crops could be cultivated with dependable rainfall
and perennial rivers. Simple irrigation canals permitted greater crop
production and longer growing seasons in dry areas. Five thousand years ago
settlements in the Indus Valley were built with pipes for water
supply and ditches for wastewater. Athens and Pompeii, like most Greco-Roman
towns of their time, maintained elaborate systems for water
supply and drainage.
As towns gradually
expanded, water was brought from increasingly remote sources, leading to
sophisticated engineering efforts, such as dams and aqueducts, At the height of
the Roman Empire, nine major systems, with an innovative layout of pipes and
well-built sew-. ers, supplied the occupants of Rome with as much water
per person as is provided in many parts of the industrial world today.
During the industrial
revolution and population' explosion of the 19th and 20th centuries, the demand
for water rose dramatically. Unprecedented construction of tens
of thousands of monumental engineering projects designed to control floods,
protect clean water supplies, and provide water for irrigation
and hydropower brought great benefits to hundreds of millions of people. Thanks
to improved sewer systems, water-related diseases such as cholera and typhoid,
once endemic throughout the world, have largely been conquered in the more
industrial nations. Vast cities, incapable of surviving on their local
resources, have bloomed in the desert with water brought from
hundreds and even thousands of miles away. Food production has kept pace with
soaring populations mainly because of the expansion of artificial irrigation
systems that make possible the growth of 40 percent of the world's food. Nearly
one fifth of all the electricity generated worldwide is produced by turbines
spun by the power of falling water.
Yet there is a dark side to
this picture: despite our progress, half of the world's population still
suffers with water services inferior to those available to the
ancient Greeks and Romans. As the latest United Nations report on access to water reiterated in November of last year, more than one billion
people lack access to clean drinking water; some two and a half billion do not
have adequate sanitation services. Preventable water-related
diseases kill an estimated 10,000 to 20,000 children every day, and the latest
evidence suggests that we are falling behind in efforts to solve these
problems. Massive cholera outbreaks appeared in the mid-1990s in Latin America,
Africa and Asia. Millions of people in Bangladesh and India drink water
contaminated with arsenic. And the surging populations throughout the
developing world are intensifying the pressures on limited water
supplies.
The effects of our water
policies extend beyond jeopardizing human health. Tens of millions of people
have been forced to move from their homes--often with little warning or
compensation--to make way for the reservoirs behind dams. More than 20 percent
of all freshwater fish species are now threatened or endangered because dams
and water withdrawals have destroyed the free-flowing river
ecosystems where they thrive. Certain irrigation practices degrade soil quality
and reduce agricultural productivity, heralding a premature end to the green
revolution. Groundwater aquifers are being pumped down faster than they are
naturally replenished in parts of India, China, the U.S. and elsewhere. And
disputes over shared water resources have led to violence and
continue to raise local, national and" even international tensions [see
box on page 44]. At the outset of the new millennium, however, the way resource
planners think about water is beginning to change. The focus is
slowly shifting back to the provision of basic human and environmental needs as
the top priority--ensuring "some for all, instead of more for some,"
as put by Kader Asmal, former minister for water affairs and
forestry in South Africa. To accomplish these goals and meet the demands of
booming populations, some water experts now call for using existing
infrastructure in smarter ways rather than building new facilities, which is
increasingly considered the option of last, not first, resort. The challenges
we face are to use the water we have more efficiently, to
rethink our priorities for water use and to identify alternative supplies of
this precious resource.
This shift in philosophy
has not been universally accepted, and it comes with strong opposition from
some established water organizations. Nevertheless, it may be
the only way to address successfully the pressing problems of providing
everyone with clean water to drink, adequate water to grow food
and a life free from preventable water-related illness. History shows that although
access to clean drinking water and sanitation services cannot
guarantee the survival of a civilization, civilizations most certainly cannot
prosper without them.
Damage from Dams
Over the past 100 years,
humankind has designed networks of canals, dams and reservoirs so extensive
that the resulting redistribution of freshwater from one place to another and
from one season to the next accounts for a small but measurable change in the
wobble of the earth as it spins. The statistics are staggering. Before 1900
only 40 reservoirs had been built with storage volumes greater than 25 billion
gallons; today almost 3,000 reservoirs larger than this inundate 120 million
acres of land and hold more than 1,500 cubic miles of water--as
much as Lake Michigan and Lake Ontario combined. The more than 70,000 dams in
the U.S. are capable of capturing and storing half of the annual river flow of
the entire country.
In many nations, big dams
and reservoirs were originally considered vital for national security, economic
prosperity and agricultural survival. Until the late 1970s and early 1980s, few
people took into account the environmental consequences of these massive
projects.
Today, however, the results
are clear: dams have destroyed the ecosystems in and around countless rivers,
lakes and streams. On the Columbia and Snake rivers in the northwestern U.S.,
95 percent of the juvenile salmon trying to reach the ocean do not survive
passage through the numerous dams and reservoirs that block their way. More
than 900 dams on New England and European rivers block Atlantic salmon from
their spawning grounds, and their populations have fallen to less than 1
percent of historical levels. Perhaps most infamously, the Aral Sea in central
Asia is disappearing because water from the Amu Darya and Syr
Darya rivers that once sustained it has been diverted to irrigate cotton.
Twenty-four species of fish formerly found only in that sea are currently
thought to be extinct.
As environmental awareness
has heightened globally, the desire to protect--and even restore--some of these
natural resources has grown. The earliest environmental advocacy groups in the
U.S. mobilized against dams proposed in places such as Yosemite National Park
in California and the Grand Canyon in Arizona. In the 1970s plans in the former
Soviet Union to divert the flow of Siberian rivers away from the Arctic
stimulated an unprecedented public outcry, helping to halt the projects. In
many developing countries, grassroots opposition to the environmental and social
costs of big water projects is becoming more and more
effective. Villagers and community activists in India have encouraged a public
debate over major dams. In China, where open disagreement with government
policies is strongly discouraged, protest against the monumental Three Gorges
Project has been unusually vocal and persistent.
Until very recently,
international financial organizations such as the World Bank, export-import
banks and multilateral aid agencies subsidized or paid in full for dams or
other water-related civil engineering projects--which often
have price tags in the tens of billions of dollars.
These organizations are
slowly beginning to reduce or eliminate such subsidies, putting more of the
financial burden on already strained national economies. Having seen so much
ineffective development in the past--and having borne the associated costs
(both monetary and otherwise) of that development--many governments are
unwilling to pay for new structures to solve water shortages
and other problems.
A handful of countries are
even taking steps to remove some of the most egregious and damaging dams. For
example, in 1998 and 1999 the Maisons-Rouges and Saint-Etienne-du-Vigan dams in
the Loire River basin in France were demolished to help restore fisheries in
the region. In 1999 the Edwards Dam, which was built in 1837 on the Kennebec
River in Maine, was dismantled to open up an 18-mile stretch of the river for
fish spawning; within months Atlantic salmon, American shad, river herring,
striped bass, shortnose sturgeon, Atlantic sturgeon, rainbow smelt and American
eel had returned to the upper parts of the river. Altogether around 500 old,
dangerous or environmentally harmful dams have been removed from U.S. rivers in
the past few years.
Fortunately--and
unexpectedly--the demand for water is not rising as rapidly as
some predicted. As a result, the pressure to build new water infrastructures
has diminished over the past two decades. Although population, industrial
output and economic productivity have continued to soar in developed nations,
the rate at which people withdraw water from aquifers, rivers
and lakes has slowed. And in a few parts of the world, demand has actually
fallen.
Demand Is Down--But for How
Long?
What explains this
remarkable turn of events? Two factors: people have figured out how to use water more efficiently, and communities are rethinking their
priorities for water use. Throughout the first three quarters of the 20th
century, the quantity of freshwater consumed per person doubled on average; in
the U.S., water withdrawals increased 10-fold while the
population quadrupled. But since 1980 the amount of water consumed per person
has actually decreased, thanks to a range of new technologies that help to
conserve water in homes and industry. In 1965, for instance,
Japan used approximately 13 million gallons of water to produce
$1 million of commercial output; by 1989 this had dropped to 3.5 million
gallons (even accounting for inflation)--almost a quadrupling of water
productivity. In the U.S., water withdrawals have fallen by more than 20
percent from their peak in 1980.
As the world's population
continues to grow, dams, aqueducts and other kinds of infrastructure will still
have to be built, particularly in developing countries where basic human needs
have not been met. But such projects must be built to higher standards and with
more accountability to local people and their environment than in the past. And
even in regions where new projects seem warranted, we must find ways to meet demands
with fewer resources, minimum ecological disruption and less money.
The fastest and cheapest
solution is to expand the productive and efficient use of water.
In many countries, 30 percent or more of the domestic water supply never
reaches its intended destinations, disappearing from leaky pipes, faulty
equipment or poorly maintained distribution systems. The quantity of water that Mexico City's supply system loses is enough to meet the
needs of a city the size of Rome, according to recent estimates. Even in more
modern systems, losses of 10 to 20 percent are common.
When water
does reach consumers, it is often used wastefully. In homes, most water is
literally flushed away. Before 1990 most toilets in the U.S. drew about six
gallons of water for each flush. In 1992 the U.S. Congress
passed a national standard mandating that all new residential toilets be
low-flow models that require only 1.6 gallons per flush--a 70 percent
improvement with a single change in technology. It will take time to replace
all older toilets with the newer, better ones. A number of cities, however,
have found the water conservation made possible by the new
technology to be so significant--and the cost of saving that water
to be so low--that they have established programs to speed up the transition to
low-flow toilets [see "Leaking Away," by Diane Martindale, on page
54].
Even in the developing
world, technologies such as more efficient toilets have a role to play. Because
of the difficulty of finding new water sources for Mexico City,
city officials launched a water conservation program that involved replacing
350,000 old toilets. The replacements have already saved enough water
to supply an additional 250,000 residents. And numerous other options for both
industrial and nonindustrial nations are available as well, including better
leak detection, less wasteful washing machines, drip irrigation and water-conserving plants in outdoor landscaping.
The amount of water needed
for industrial applications depends on two factors: the mix of goods and
services demanded by society and the processes chosen to generate them. For
instance, producing a ton of steel before World War II required 60 to 100 tons
of water. Current technology can make a ton of steel with less
than six tons of water. Replacing old technology with new techniques reduces water needs by a factor of 10. Producing a ton of aluminum,
however, requires only one and a half tons of water. Replacing
the use of steel with aluminum, as has been happening for years in the
automobile industry, can further lower water use. And
telecommuting from home can save the hundreds of gallons of water required to
produce, deliver and sell a gallon of gasoline, even accounting for the water required to manufacture our computers. The largest single
consumer of water is agriculture--and this use is largely inefficient. Water is
lost as it is distributed to farmers and applied to crops. Consequently, as
much as half of all water diverted for agriculture never yields
any food. Thus, even modest improvements in agricultural efficiency could free
up huge quantities of water [see "Growing More Food with
Less Water," by Sandra Postel, on page 46]. Growing tomatoes with
traditional irrigation systems may require 40 percent more water
than growing tomatoes with drip systems. Even our diets have an effect on our
overall water needs. Growing a pound of corn can take between
100 and 250 gallons of water, depending on soil and climate conditions and
irrigation methods. But growing the grain to produce a pound of beef can
require between 2,000 and 8,500 gallons. We can conserve water
not only by altering how we choose to grow our food but also by changing what
we choose to eat.
Shifting where people use water can also lead to tremendous gains in efficiency. Supporting
100,000 high-tech California jobs requires some 250 million gallons of water a year; the same amount of water used in the agricultural
sector sustains fewer than 10 jobs--a stunning difference. Similar figures
apply in many other countries. Ultimately these disparities will lead to more
and more pressure to transfer water from agricultural uses to
other economic sectors. Unless the agricultural community embraces water
conservation efforts, conflicts between farmers and urban water
users will worsen.
The idea that a planet with
a surface covered mostly by water could be facing a water shortage seems
incredible. Yet 97 percent of the world's water is too salty
for human consumption or crops, and much of the rest is out of reach in deep groundwater
or in glaciers and ice caps. Not surprisingly, researchers have investigated
techniques for dipping into the immense supply of. water in the
oceans. The technology to desalinate brackish water or saltwater is well
developed, but it remains expensive and is currently an option only in wealthy
but dry areas near the coast. Some regions, such as the Arabian Gulf, are
highly dependent on desalination, but the process remains a minor contributor
tO overall water supplies, providing less than 0.2 percent of
global withdrawals [see "Sweating the Small Stuff," by Diane
Martindale, on page 52]. With the process of converting saltwater to freshwater
so expensive,' some companies have turned to another possibility: moving clean water in ships or even giant plastic bags from regions with an
abundance of the resource to those places around the globe suffering from a
lack of water [see "Bagged and Dragged," by Peter H.
Gleick, on page 53]. But this approach, too, may have serious economic and
political constraints.
Rather than seeking new
distant sources of water, smart planners are beginning to
explore .using alternative kinds of water to meet certain needs. Why should
communities raise all water to drinkable standards and then use
that expensive resource for flushing toilets or watering lawns? Most water ends
up flowing down the drain after a single use, and developed countries spend
billions of dollars to collect and treat this wastewater before dumping it into
a river or the ocean. Meanwhile, in poorer countries, this water
is often simply returned untreated to a river or lake where it may pose a
threat to human health or the environment. Recently attention has begun to
focus on reclaiming and reusing this water.
Wastewater can be treated
to different levels suitable for use in a variety of applications, such as
recharging groundwater aquifers, supplying industrial processes, irrigating
certain crops or even augmenting potable supplies. In Windhoek, Namibia, for
instance, residents 'have used treated wastewater since 1968 to supplement the
city's potable water supply; in drought years, such water has
constituted up to 30 percent of Windhoek's drinking water supply [see
"Waste Not, Want Not," by Diane Martindale, on page 55]. Seventy
percent of Israeli municipal wastewater is treated and reused, mainly for
agricultural irrigation of nonfood crops. Efforts to capture, treat and reuse
more wastewater are also under way in neighboring Jordan. By the mid-1990s
residents of California relied on more than 160 billion gallons of reclaimed water annually for irrigating landscapes, golf courses and crops,
recharging groundwater aquifers, supplying industrial processes and even
flushing toilets.
New approaches to meeting water needs will not be easy to implement: economic and
institutional structures still encourage the wasting of water and the
destruction of ecosystems. Among the barriers to better water
planning and use are inappropriately low water prices, inadequate information
on new efficiency technologies, inequitable water allocations, and government
subsidies for growing water-intensive crops in arid regions or
building dams.
Part of the difficulty,
however, also lies in the prevalence of old ideas among water
planners. Addressing the world's basic water problems requires fundamental
changes in how we think about water, and such changes are
coming about slowly. Rather than trying endlessly to find enough water to meet
hazy projections of future desires, it is time to find a way to meet our
present and future needs with the water that is already
available, while preserving the ecological cycles that are so integral to human
well-being.
WHERE THE WATER WILL BE IN 2025
The
total amount of water withdrawn globally from rivers, underground aquifers and
other sources has increased nine-fold since 1900 (chart). Water
use per person has only doubled in that time, however, and it has even declined
slightly in recent years. Despite this positive trend, some experts worry that
improvements in water-use efficiency will fail to keep pace
with projected population growth. Estimated annual water availability per
person in 2025 (map) reveals that at least 40 percent of the world's 7.2
billion people may face serious problems with agriculture, industry or human
health if they must rely solely on natural, endowments of freshwater. Severe water shortages could also strike particular regions of water-rich
countries, such as the U.S. and China. People's access to water also depends on
factors not reflected here, such as political and economic conditions, changing
climate patterns and available technology.
Myths,
legends and written histories reveal repeated controversy over freshwater
resources since ancient times. Scrolls from Mesopotamia, for instance, indicate
that the states of Umma and Lagash in the Middle East clashed over the control
of irrigation canals some 4,500 years ago.
Throughout
history, water has been used as a military and political goal,
as a weapon of war and even as a military target. But disagreements most often
arise from the fact that water resources are not neatly
partitioned by the arbitrary political borders set by governments. Today nearly
half of the land area of the world lies within international river basins, and
the watersheds of 261 major rivers are shared by two or more countries.
Overlapping claims to water resources have often provoked
disputes, and in recent years local and re- gional conflicts have escalated
over inequitable allocation and use of water resources.
A
small sampling of water conflicts that occurred in the 20th century
demonstrates that treaties and other international diplomacy 'can sometimes
encourage opposing countries tO cooperate--but not always before blood is shed.
The risk of future strife cannot be ignored: disputes over water
will become more common over the next several decades as competition for this
scarce resource intensifies.
U.S.
1924
Local
farmers dynamite the Los Angeles aqueduct several times in an attempt to
prevent diversions of water from the Owens Valley to Los
Angeles.
India
and Pakistan 1947 to 1960
Partitioning
of British India awkwardly divides the waters of the Indus
River valley between India and Pakistan. Competition over irrigation supplies
incites numerous conflicts between the two nations; in one case, India stems
the flow of water into Pakistani irrigation canals. After 12
years of World Bank-led negotiations, a 1960 treaty helps to resolve the
discord.
Egypt
and Sudan 1958
Egypt
sends troops into contested territory between the two nations during sensitive
negotiations concerning regional politics and water from the
Nile. Signing of a Nile waters treaty in 1959 eases tensions.
Israel,
Jordan and Syria 1960s and 1970s
Clashes
over allocation, control and diversion of the Yarmouk and Jordan rivers
continue to the present day.
South
Africa 1990
A
pro-apartheid council cuts off water to $0,000 black residents
of Wesselton Township after protests against wretched sanitation and living
conditions.
Iraq
1991
During
the Persian Gulf War, Iraq destroys desalination plants in Kuwait. A United
Nations coalition considers using the Ataturk Dam in Turkey to shut off the water flow of the Euphrates River to Iraq.
India
1991 to present
An
estimated 50 people die in violence that continues to erupt between the Indian
states of Karnataka and Tamil Nadu over the allocation of irrigation water from the Cauvery River, which flows from one state into the
other.
Yugoslavia
1999
NATO
shuts down water supplies in Belgrade and bombs bridges on the
Danube River, disrupting navigation.
A
comprehensive chronology of waterrelated conflicts can be found at www.
worldwater.org/conflictlntro.htm
The
Author
PETER H. GLEICK is director of the Pacific Institute for Studies in Development, Environment and Security, a nonprofit policy research think tank based in Oakland, Calif. Gleick co-founded the institute in 1987. He is considered one of the world's leading experts on freshwater problems, including sustainable use of water, water as it relates to climate change, and conflicts over shared water resources.
Further
Information
THE
WORLD'S WATER 1998-1999. Peter H. Gleick. Island Press, 1998. INTERNATIONAL
RIVER BASINS OF THE WORLD. Aaron T. Wolf et al. in Water
Resources Development, Vol. 15, No. 4, pages 387-427; December 1999. THE
WORLD'S WATER 2.000-2.00 I. Peter H. Gleick. Island Press,
2000. Information on the world's water resources can be found at www.
worldwater.org United Nations Environment Program Global Environment Monitoring
System's Fresh- water Quality Program can be found at
www.cciw.ca/gems/ VISION 2I: A SHARED VISION FOR HYGIENE, SANITATION AND WATER
SUPPLY. Water Supply and Sanitation Collaborative Council.
Available at www. wsscc.org/vision21/docs/ index.html