Transcript Guided Notes about Water Resources

Guided Notes about
Water Resources
Chapter 25, Section 4
1. Only 3 percent of the Earth’s water is
freshwater. Of this, 2.997% is locked up in ice
caps or glaciers or stored as groundwater that
is too deep to extract. This leaves only 0.003%
of the Earth’s total volume of water available
to humans for domestic, agricultural, and
industrial purposes.
2. The world’s oceans help regulate climate,
provide habitats for marine organisms,
dilute and degrade many pollutants, and
help shape the Earth’s surface
3. Water can exist as a liquid over a wide
range of temperatures because of the
hydrogen bonds between water
molecules.
4. Water has a high boiling point, 100˚C, and
a low freezing point, O˚C. As a result,
water remains liquid in most
environments on Earth.
5. Liquid water can store a large amount of
heat without a correspondingly high
increase in temperature. This is
responsible for water’s ability to regulate
earth’s climate.
6. Liquid water can dissolve a wide variety of
compounds, which enables water to carry
nutrients into, and waste products out of,
the tissues of living things.
7. Unlike most liquids, water expands
when it freezes.
8. Freshwater resources are not distributed
evenly across Earth’s landmasses. The
eastern states receive ample precipitation
while the western states often have too
little.
9. About 25 countries, most in Africa,
experience chronic water shortages. This
number is expected to rise to 90 countries
by the year 2025.
10. The current rate of withdrawal of
freshwater worldwide is 5 times greater
than it was 50 years ago. Withdrawal
rates are expected to double again within
the next 20 years.
11. Nearly 80% of water used for
irrigation evaporates or seeps into the
ground before it can be used by
crops.
12. Most countries manage their freshwater
supplies by building dams, transporting
surface water, or tapping groundwater.
What are the advantages of building a dam
across a river valley?
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they control flooding downstream
Water can be released as necessary
Provides water for hydroelectric power
How do countries transport surface water
today?
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Many countries use aqueducts, tunnels, and
underground pipes to bring water from areas
where it is plentiful to where it is needed.
15. Because groundwater is the source of many
streams in the U.S, groundwater depletion also
affects stream flow.
16. Most experts agree that they best way to
meet the need for freshwater is to use
available supplies more efficiently.
List several ways to reduce domestic use of
freshwater:
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Farmers can change their irrigation methods,
such as trickle irrigation
Industries can use recycled water for
manufacturing processes
Homeowners can install low-flow toilets, plant
drought-resistant plants for landscaping, and fix
leaking pipes or faucets