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A Fragile Resource
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THE IMPORTANCE OF WATER
THE IMPORTANCE OF
WATER
The view of planet Earth
from outer space reveals that it is different from other planets in the
Solar System. Earth is a predominantly blue planet because of the water
that covers three-fourths of its surface. Water has a tremendous effect
on our planet: it helped shape the continents, it moderates our climate,
and it allows living organisms to evolve and survive.
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Life on planet Earth would be
impossible without water. All life forms, from simple bacteria to
complex multicellular plants and animals, contain water. Humans ate
composed of approximately 70 percent water (by weight), and we
depend on water for our survival as well as for our convenience: we
drink it, cook with it, wash with it, travel on it, and use an
enormous amount of it for agriculture, manufacturing, mining,
energy production, and' waste disposal.
Although Earth has plenty of
water, it is distributed unevenly, and serious water supply
problems exist. In regions where fresh water is in short supply,
such as deserts, obtaining it becomes critically important; and
because the use of water for one purpose decreases the amount
available for other purposes, serious conflicts often arise over how
water should be used. Even regions with readily available fresh
water are not without problems, however, and maintaining the quality
and quantity of water is a top priority. |
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Worldwide, we are using increasingly
more water, in part because our population is increasing and in part
because, on the average, each person is using more water. The World
Resources Institute estimates that water use has increased 4 to 8
percent each year since 1950. The rate of increase is now
slowing because water use has stabilized in developed nations, although
it is still increasing in developing countries.
To meet the growing need for water, we
try to augment our supply by building dams to create reservoirs
(artificial lakes in which water is stored for later use) and by
diverting river water. In many areas, the quantity of water is not as
critical as its quality, and steps must be taken to ensure a supply of
clean water. All of these efforts to obtain and maintain a steady supply
of clean water involve considerable expense.
This chapter examines some of the
ecological process and human activities that affect the availability of
water. Water quality, including water pollution, is such significant
issue that it is covered separately.
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