1
How is water distributed on Earth, and what are the sources of freshwater? How does water cycle through the environment?
INFOGRAPHICS 14.1 AND 14.2
Approximately 75% of Earth’s surface is covered with water. The amount of that water that is drinkable by humans is:
nearly all of it.
about half of it.
perhaps 1/10 of it.
much less than 1%.
D
Draw a flowchart of the water cycle. (Don’t copy from the book; create your own small drawing.) Follow a single water molecule from a cloud through some portion of the cycle, including a living organism, and back to a cloud.
Pictures will vary, but should include a cloud, land, a body of water, and plants, animals, or both. They should show water falling as precipitation and rising as evaporation or transpiration.
2
What are the causes and consequences of water scarcity?
INFOGRAPHIC 14.3
True or False: The sector that uses the highest percentage of water globally is industry.
FALSE
When access to water is limited only by one’s ability to pay for it, this is known as:
physical water scarcity.
virtual water scarcity.
economic water scarcity.
unpredictable water scarcity.
C
Why do the problems of water scarcity and unsanitary water conditions often occur together?
In areas with little water, there is often not enough water to provide separate sources for potable water and for sanitation so waste often goes directly into sources of water than people draw from for drinking, cooking and bathing. In other places the lack of sanitation, usually due to poverty, directly pollutes the water, thus decreasing the amount of usable water available.
4
What is an aquifer, how does it receive water, and what problems emerge when too much water is removed?
INFOGRAPHIC 14.4
The uppermost water level of the saturated zone of an aquifer is found is known as the_________ __________.
Water table
True or False: Most aquifers are not underground lakes of water but rather are regions of porous rock saturated with water.
TRUE
Infiltration is:
made easy in urban and suburban areas by all of the lawns.
made harder in urban and suburban areas by roads, buildings, and lawns.
the process of removing particulate matter from sewage.
what happens when seawater enters a freshwater system.
B
If too much water is removed by a well in coastal areas:
the water table will rise.
a cone of depression will form.
the aquifer might collapse.
saltwater can seep into the aquifer.
D
4
What are some of the ways that our wastewater is treated to make it potable or safe to release into the environment?
INFOGRAPHIC 14.5
True or False: Potable water is water that is safe to consume.
TRUE
The main difference between high-tech and low-tech methods of wastewater treatment is that high-tech methods:
use toxic chemicals to purify water.
use bacteria to break down solids.
filter water at the start of the process.
are less expensive.
A
What are some of the things that communities in the United States do to deal with their wastewater?
In the United States, some kind of treatment of wastewater is required. The most common method is to filter the incoming wastewater and then let the solids settle out. After that, the liquid is sent through a series of ponds where bacteria help breakdown the material; some chemical treatment may also be done. Some communities build wetlands to clean the water and provide places for wildlife. Some use it to water parklands and golf courses or for other irrigation. Some coastal areas simply pump it out to sea, with or without treatment; others pump it into the aquifer to prevent saltwater infiltration. Some areas use reverse osmosis and UV light disinfection to render the wastewater potable.
5
What can be done to address water scarcity issues?
INFOGRAPHIC 14.6 AND TABLE 14.1
Many people say that desalination (removing the salt from ocean water) is the obvious way around our water shortages. This is:
becoming relatively easy and inexpensive and will be common soon.
inexpensive now, but it is difficult to route the water from the coasts to inland areas.
still very expensive and uses a great deal of energy.
not being done at this time.
C
Dams can be used to store water and increase water supplies, but they come with trade-offs such as:
habitat destruction.
loss of water from evaporation.
regional conflicts downstream from the dam.
A and B.
A, B, and C.
E
One creative way that some communities deal with wastewater is:
diverting it, unfiltered, to agricultural fields that need irrigation
using microfiltration, then bottling and selling it as mineral water.
pumping it through a separate water system for people to use for laundry and for yard irrigation.
evaporating it in gigantic reservoirs, creating additional clouds and rain.
C
How did Orange County address the problems of water scarcity, aquifer saltwater intrusion, and high volumes of wastewater? Would you support this solution in your own community? Explain.
Orange County purified their wastewater to the point that it was potable and then injected it into their wells to replace the water that was being removed. This prevented saltwater intrusion, reduced or eliminated the release of partially treated wastewater into the ocean, and increased their potable water supplies. Students may be in favor for this solution or may reject it for their own water supply but they should present reasons for their opinion.
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