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LEARNING OBJECTIVES
Although water is one of the most abundant resources on Earth, many important
issues and problems are involved in water management. After reading this
chapter, you should understand:
•
What a water budget is, and why it is useful in analyzing water supply
problems and potential solutions.
• What groundwater is, and what environmental problems are associated with its
use.
• How water can be conserved at home and in industrial and agricultural
practice.
• Why sustainable water management will become more difficult as the demand for
water increases.
• What the environmental impacts are of water projects such as dams,
reservoirs, canals, and channelization.
• What a wetland is, how wetlands function, and why they are important.
•
•
What hazards are presented by river flooding.
Why we are facing a growing global water shortage linked to our food supply.
Summary
• Water is a liquid with unique characteristics that has made life on
Earth possible.
• Although it is one of the most abundant and important renewable
resources on Earth, more than 99% of Earth’s water is unavailable or
unsuitable for beneficial human use because of its salinity or
location.
• The pattern of water supply and use on Earth at any particular point
on the land surface involves interactions and linkages among the
biological, hydrological, and rock cycles. To evaluate a region’s
water resources and use patterns, a water budget is developed to
define the natural variability and availability of water.
• During the next several decades, it is expected that the total water
withdrawn from streams and groundwater in the United States will
decrease slightly, but the consumptive use will increase because of
greater demands from a growing population and industry.
• Water withdrawn from streams competes with in-stream needs, such as
maintaining fish and wildlife
therefore cause conflicts.
habitats
and
navigation,
and
may
• Groundwater use has resulted in a variety of environmental problems,
including overdraft, loss of vegetation along watercourses, and land
subsidence.
• Because agriculture is the biggest user of water, conservation of
water in agriculture has the most significant effect on sustainable
water use. However, it is also important to practice water
conservation at the personal level in our homes and to price water to
encourage conservation and sustainability.
• There is a need for a new philosophy in water resource management
that considers sustainability and uses creative alternatives and
variable sources. Development of a master plan involves inclusion of
normal sources of surface water and groundwater, conservation
programs, and use of reclaimed water.
• Development of water supplies and facilities to more efficiently move
water may cause considerable environmental degradation; construction
of reservoirs and canals and channelization of rivers should be
considered carefully in light of potential environmental impacts.
• Wetlands serve a variety of functions at the ecosystem level that
benefit other ecosystems and people.
• Flooding is perhaps the most universal natural hazard in the world;
both the frequency and the severity of flooding of small streams are
increased by urbanization. The preferable and most environmentally
sound adjustment to flooding is land-use planning that avoids
building on floodplains.
• The Colorado River in the southwestern United States and northern
Mexico is one of the most regulated rivers in the world.
Understanding links among physical, biological, and social systems of
the Colorado River is necessary to manage its water resources and
ecosystems.
• We are facing a growing global water shortage linked to the food
supply.