|
|
Home
> Environment
> Water:
A Fragile Resource
> WATER
MANAGEMENT
WATER MANAGEMENT
People have
always thought of water as different from other resources. Resources
such as coal or gold may be owned privately and sold as free-market
goods, but we view water as public property.
Historically, both in the United States and in other countries, water
rights were bound with land ownership. As more and more users compete
for the same water, however allocation decisions are increasingly being
made by state or provincial governments. This is true in both developed
and developing countries, although the details of state-level
Trusteeships vary. Some countries have separated land and water
ownership so that water rights are sold separately.
|
Because
rivers usually flow through more than one government
jurisdiction, jurisdictions or states must create agreements with
each other about the management of a river's resources. Such
interstate cooperation permits comprehensive rather than piecemeal
management of a river. In addition, these arrangements allow the
water to be divided fairly between the jurisdictions, which then
apportion their respective shares to individual users according to
an established set of priorities.
Groundwater
management is more complicated, in part because the extent of local
groundwater supplies is not known. Some states manage groundwater,
particularly where demand exceeds supply. Groundwater management
includes issuing permits to drill wells, limiting the number of
wells in a given area, and restricting the amount of water that may
be pumped from each well.
The
price of water varies, depending on how ii is used. Historically,
domestic use is most expensive, and agricultural use is least
expensive. In any case, the consumer rarely pays directly for the
entire cost of water (including its transportation, storage, and
treatment). State and federal governments heavily subsidize water
costs, so we pay for some of the cost of water indirectly, through
taxes. |
|
The main
goal of water management is to provide a sustainable supply of
high-quality water. Increasingly, state and local governments are
considering the price of water as a mechanism to help ensure an
adequate supply of water. Raising the price of water to users so
that it reflects the actual cost generally promotes more efficient use
of water.
France is a
model of water management because it has an effective, comprehensive
regional water plan. France is divided into eight separate regions that
are managed by government agencies with public and individual user
representation. Water taxes finance additional water projects such as
the construction of water treatment plants. Industrial users pay a
pollution tax, but they can be exempted from this tax if they clean up
the water after they use it and before they discharge it. This policy
has substantially reduced water pollution in France.
Dams and
Reservoirs
Dams ensure a
year-round supply of water in areas that have seasonal precipitation or
snowmelt. Dams confine water in reservoirs, from which the flow is
regulated. Dams have other
benefits, including the generation of
electricity. They provide flood control for areas downstream, because a
reservoir can hold a large amount of excess water during periods of
heavy precipitation and then release it gradually. Some of i reservoirs
formed by dams also have recreational benefits: people swim, boat, and
fish in them. Many people, however, feel that the drawbacks dams,
including the cost of building them, far outweigh any benefits they
provide (see Focus On: Damming the Big Muddy). (For a discussion of the
impact of dams on natural fish communities, see Meeting the Challenge:
The Columbia .River—A Case Study in Water Management.)
Water Diversion Projects
One way to increase the natural supply of
water to a particular area is to divert water from areas where it is in
plentiful supply. This is done by pumping water through a system of
aqueducts. Much of southern California receives its water supply via
aqueducts from northern California. Water from the Colorado River is
also diverted into southern California.
Large-scale water diversion projects are
controversial and expensive. The Central Arizona Project, recently
completed at a cost of almost $4 billion, pumps water from the Colorado
River to Phoenix and Tucson. As we saw earlier, damage is done to a
river or other body of water when a major portion of its water is
diverted. Pollutants, which would have been diluted in the normal river
flow, reach higher concentrations when much of the flow has been
removed. Wildlife, including fish, may decline in number and diversity.
Although no one denies that people must have water, opponents of water
diversion projects contend that serious water conservation efforts would
eliminate the need for additional large-scale water diversion.
Harvesting Icebergs
For well over a decade, visionaries in
arid areas such as Saudi Arabia, California, and Australia have toyed
with the idea of towing icebergs from the Antarctic or Arctic so they
could be melted down to supply fresh water. Skeptics voice concerns
about the ownership of icebergs, particularly in Antarctica. The
effects on marine wildlife of introducing an iceberg into warm tropical
waters are unknown.
The Department of Natural Resources in
Alaska has begun issuing permits that allow icebergs to be collected.
One entrepreneur plans to lift small icebergs from the sea, chop them
into smaller pieces, and ship them to Japan, where they will be used as
"gourmet" ice cubes. (Glacial ice makes better ice cubes than freezer
ice because it is extremely pure and takes longer to melt.)
Australians are also serious about
harvesting icebergs. They plan to wrap Antarctic icebergs in strong,
lightweight fabrics to hold the water from melting during transport.
Glacial ice will likely be cost-competitive with other fresh water
sources in Australia, even taking into account the expense of
harnessing, wrapping, and towing the icebergs.
Desalinization
Seawater and saline groundwater can be
made fit to drink through the removal of salt, called desalinization (or
desalination), by several methods. One of the most common is
distillation—heating the salt water until the water evaporates, leaving
behind a crust of salt; the water vapor is then condensed to produce
fresh water. Another method, called reverse osmosis, involves forcing
salt water through a membrane that is permeable to water but not to
salt.
Desalinization is expensive because it
requires a large input of energy. Recent advances in reverse osmosis
technology have increased its efficiency so that it requires much less
energy than distillation.
|
