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446 Chapter 14 • Study Guide

Lesson 1 earth: the Water planet• As a natural resource, fresh water is renewable. However,

quantities of fresh water on Earth are limited. • Surface water travels across Earth’s surface as runoff and

collects in a river system. All of the land that drains water into a river system is called a watershed.

• Water that soaks through permeable layers of soil and rock from the surface is called groundwater. Groundwater is contained within aquifers that can be accessed by wells.

fresh water (421) permeable (424) surface water (422) impermeable (424) runoff (422) aquifer (424) river system (422) water table (424) watershed (422) recharge zone (425) groundwater (424) well (425)

Lesson 2 Uses of Fresh Water• Fresh water is used for agricultural, industrial, and

personal activities. Globally, most fresh water is used for agriculture.

• Because of overuse, surface water resources are being depleted. Water diversions and dams move and collect water for human purposes.

• Groundwater is being used, primarily for irrigation, faster than it can be replenished.

• There are many ways to decrease demand for water in agri-culture, industry, and at home. Conserving water in each of these areas is necessary to address freshwater depletion.

water diversion (428) dam (428) reservoir (428) salinization (431) desalination (432) xeriscaping (434)

Lesson 3 Water pollution• Water pollution can come from point or nonpoint sources.

Major types of water pollution are nutrient pollution, toxic-chemical pollution, sediment pollution, biological pollution, and thermal pollution.

• Any form of water pollution can affect groundwater. It can take decades to clean up groundwater pollution, so every effort should be made to prevent it from occurring.

• Oceans are polluted with oil, toxic chemicals, and nutri-ents that run off from land.

• Government regulation and water treatment are two ways of decreasing the effects of water pollution.

point-source pollution (435) nonpoint-source pollution (435) cultural eutrophication (436) wastewater (436) algal bloom (436) pathogen (438) red tide (440) septic system (443)

InquIry LABs And ActIvItIes• Watershed Boundaries Water always runs downhill. Use this fact and a topo-

graphical map to delineate watershed boundaries.• The Water You Drink How does your drinking water measure up? Analyze

your local EPA-required drinking water quality report.• Testing Water Quality Test the waters—literally. Follow these procedures to

investigate the water quality of a local water sample.

Lesson 2 How can we change the

way we use water?

Lesson 1 Where is all of our water?

Lesson 3 How does water pollution affect

humans and ecosystems?

Why are we running out of water?

STUDY RESOURCES

Chapter 14 Self Test • Chapter 14 Worksheets • Chapter 14 Overview Presentation (for PowerPoint)

Review Concepts and Terms 1. More than 97 percent of Earth’s total water supply

is found in a. ice sheets. b. the oceans. c. the atmosphere. d. groundwater.

2. The land area that supplies water to a river system is called a

a. divide. c. watershed. b. wetland. d. tributary.

3. The water table is the upper limit of the a. zone of saturation. c. aquifer zone. b. zone of aeration. d. well zone.

4. You must build a model of an aquifer for a science project. What material would be the best to use for the layer that will hold water?

a. an impermeable material, such as clay b. a liquid, such as oil c. a permeable material, such as gravel d. a material that does not have pores

5. One process used to obtain fresh water from salt water is called

a. coagulation. c. recharge. b. filtration. d. desalination.

6. Globally, MOST fresh water used by humans is for

a. drinking and cooking. b. washing and home use. c. agricultural irrigation. d. electrical production.

7. The All-American Canal, which brings water from the Colorado River to farm fields in California, is an example of a

a. dam. c. reservoir. b. water diversion. d. well.

8. Which of the following does NOT contribute to water conservation?

a. drip irrigation b. xeriscaping c. using low-flow faucets and shower heads d. watering lawns during peak sunlight hours,

when plants need water most

9. An oil spill is an example of a. point-source pollution. b. nonpoint-source pollution. c. reversible pollution. d. natural pollution.

10. Chlorine is often added during water treatment to a. make particles form clumps. b. kill disease-causing organisms. c. improve the taste of water. d. remove objects such as fish and trash.

Modified True/FalseWrite true if the statement is true. If it is false, change the underlined word or words to make the statement true.

11. Most fresh water on Earth is liquid. 12. Water moves through permeable materials. 13. The photo below shows a nonpoint source of

pollution.

14. Cultural eutrophication can result from toxic-chemical pollution.

15. Dams create aquifers, artificial lakes that humans use for water storage.

The Central Case in this chapter explored the complex and urgent situation regarding water shortages in Nevada. Based on what you have learned, what do you think Nevada should do? Use examples from the Central Case and the lesson to support your ideas.

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ANSWERS

Chapter Assessment For answers to the Chapter Assessment, see page A–23 at the back of the book.

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Short Answer 18. Why is so little of Earth’s water available for

human use? 19. Describe three benefits and three costs of dam-

ming rivers. 20. Why do many scientists consider groundwater

pollution a greater problem than surface water pollution?

21. A substance added to gasoline is found in local wells. Suggest a possible point source and non-point source of this pollution.

22. Describe one way farmers can reduce the amount of water lost during irrigation.

23. Explain how desalination “makes” fresh water. Where is the technology primarily being used?

Critical Thinking 24. Apply Concepts Your friend says that we can

reduce how much water we use by eating less meat. Is she right? Explain your answer.

25. Form an Opinion To conserve water, should com-munities limit how often people can do things such as water their lawns or wash their cars? Why or why not?

26. Calculate Growing wheat for one loaf of bread requires about 550 liters of water. If a family eats three loaves a week, how much water would be used to produce the family’s bread supply each year?

27. Apply Concepts Define point-source pollution and nonpoint-source pollution. Which of the two is easier to identify? Which is easier to control? In your opinion, which poses the greatest threat to fresh water?

28. Apply Concepts Describe three ways in which your own actions contribute to water pollution. Then, describe three ways in which you could reduce the effects of these actions.

29. Form an Opinion To prevent water pollution, a factory proposes pumping its wastes into the ground instead of into a river. Would you support this proposal? Why or why not?

Reading ComprehensionRead the following selection and answer the questions that follow.On a September day in 1999, people began to notice that Lake Jackson in the Panhandle region of northern Florida was shrinking. Within a few days, it was almost gone. A sinkhole had opened beneath the lake and drained it, along with all of its inhabit-ants including fish and alligators. As aquifers lose water, rock and soil layers can become weaker and less capable of supporting overlying layers of earth and any human struc-tures built on them. In such cases, the land surface above may subside, or sink. Sometimes subsid-ence can occur locally and suddenly in the form of sinkholes, which are areas where the ground gives way with little warning. Once the ground subsides, soil becomes compacted, losing the porosity that enabled it to hold water. Recharging a depleted aquifer may therefore become more difficult.

16. Sinkholes occur when a. too much weight above an aquifer causes it to

cave in. b. the water level in an aquifer rises, pushing

through to the surface. c. excessive water use lowers a water table and

causes subsidence. d. new aquifers form.

17. A serious problem that results from the depletion of aquifers is

a. the water tends to overflow and flood the entire area.

b. the surrounding soil is compacted and loses its porosity.

c. the aquifer increases in size, draining a larger surface area and leaving less water in rivers, streams, and lakes.

d. the aquifer decreases in size and new aquifers form.

448 Chapter 14 • Assessment

Ecological Footprints

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Data from Wallace, J. S. , 2000. Increasing agricultural water use efficiency to meet future food production. Agriculture, Ecosystems and Environment 82: 105–119.

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With StandardShower Heads(liters per year)

With Low-�owShower Heads(liters per year)

Savings WithLow-�owShower Heads(liters per year)

Data from U.S. EPA, 1995. Chapter 3—How to conserve water and use it e�ectively. EPA 841-B-95-002.

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Read the information below. Copy the table into your notebook, record your calculations, and answer the questions.

One of the single greatest personal uses of water is for showering. Older standard shower heads release 17 liters of water per minute, but low-flow shower heads release only 9 liters per minute. Given an average daily shower time of 10 minutes, fill in the footprint table. 1. For the table, you calculated how much water

can be saved per person per year by using low-flow shower heads. Use that calculation to determine how much water could be saved per person per day.

2. How much water would you be able to save per day by shortening your average shower time from 10 minutes to 8 minutes? Assume you are using an older standard shower head.

3. Compare your answers to Questions 1 and 2. Is more water saved by showering the full 10 minutes using a low-flow shower head, or by showering for 8 minutes using a standard shower head?

32. Calculate Most men require 2700 Calories a day to maintain their weight. How many liters of water are needed to produce one day’s worth of food if 2300 of those Calories come from veg-etables, and 400 Calories come from meat?

33. Calculate How many liters of water would be saved daily if all 2700 Calories of a man’s daily diet came from plant-based foods rather than 2300 from vegetables and 400 from meat?

Write About It 34. Opinion Which is easier, preventing pollution or

cleaning up pollution? Give an example to sup-port your answer.

35. Explanation Your community is considering building a dam on a nearby river to reduce flood-ing. Would you support this proposal? Explain your reasoning.

36. Apply the BIGQUESTION Write a public ser-vice announcement that teaches people about the effects human activities have on fresh water. The goal of the announcement is to explain the importance of sustainable water practices. Your intended audience is the general public, so you may need to provide background on why fresh water is a renewable, but limited resource. Present your announcement to the class. You may use visuals to support your ideas.

Analyze DataThe graph below shows how much water per Calorie is needed to produce plant-based food (fruits, vegetables, and grains) and animal-based food (meat and dairy). Use the data to answer the questions.

30. Interpret Graphs How many liters of water per Calorie are needed to produce plant-based food?

31. Interpret Graphs How many liters of water per Calorie are needed to produce animal-based food?