1. Water “When the well is dry, we learn the worth of water. ”
Water “When the well is dry, we learn the worth of water.” - Benjamin Franklin
Chapter 11

2. 11-1: Water Resources
Water is essential to life on Earth. Humans can live for more than month without food, but we can live for only a few days without water.

3. Water Resources Two kinds of water found on Earth:
Fresh water, the water that people can drink, contains little salt.
Salt water, the water in oceans, contains a higher concentration of dissolved salts.

4. Global Water Distribution
Although 71 percent of the Earth’s surface is covered with water, nearly 97 percent of Earth’s water is salt water in oceans and seas.

5. Global Water Distribution
“Tip of the iceberg”
Of the fresh water on Earth, about 77 percent is frozen in glaciers and polar icecaps.

6. Global Water Distribution
The fresh water we use comes mainly from lakes and rivers and from a relatively narrow zone beneath the Earth’s surface.
Only a small percentage
of the water on Earth is
liquid fresh water that
humans can use.

7. Surface Water
Surface water – All the bodies of fresh water, salt water, ice, and snow, that are found above the ground
Throughout history, people have built cities and farms near reliable sources of water.

8. Surface Water
River system – a flowing network of rivers and streams draining a river basin
The Amazon River system is
the largest river system in the
world it drains an area of land
that is nearly the size
of Europe.

9. Surface Water
Watershed – the area of land that is drained by a water system

10. Surface Water
The amount of water that enters a watershed varies throughout the year.
Rapidly melting snow as well as spring and summer rains can dramatically increase the amount of water in a watershed.

12. Groundwater
Most of the fresh water that is available for human use cannot be seen, as it exists underground.
Groundwater – the water that is beneath the Earth’s surface

13. Groundwater
Much of the rain water percolates through the soil and down into the rocks beneath.

14. Groundwater
Water table – A level of the Earth’s surface where the rocks and soil are saturated with water

15. Groundwater
In wet regions, the water table may be at Earth’s surface. But in deserts, the water table may be hundreds of meters beneath Earth’s surface

16. Groundwater
Aquifer – A body or rock or sediment that stores groundwater and allows the flow of groundwater
They are an important water source for many cities

17. Groundwater
Porosity – The percentage of the total volume of a rock or sediment that consists of open spaces

18. Groundwater
Permeability – The ability of a rock or sediment to let fluids pass through its open spaces or pores

19. Groundwater
Recharge zone – An area in which water travels downward to become part of an aquifer
Recharge zones are environmentally sensitive areas because any pollution in the recharge zone can also enter the aquifer.

20. Groundwater Well – A hole that is dug or drilled to reach groundwater
We dig wells because ground water may be a more reliable source of water than surface water and because water is filtered and purified as it travels underground.

21. 11-2: Water Use and Management There are three major uses for water: residential use, agricultural use, and industrial use.

22. Agriculture makes up the majority of both water withdrawal and consumption.22

23. Residential Water Use
There are striking differences in residential water use throughout the world. For example, the average person in the United States uses about 300 L of water a day. But in India, the average person uses only 41 L of water everyday.

24. Residential Water Use
In the U.S., only about half of residential water use is for activities inside the home, such as drinking and cooking.

26. Water Treatment Most water must first be made potable.
Potable – suitable for drinking
Water treatment removes elements such as mercury, arsenic, and lead, which are poisonous to humans even in low concentrations.
These elements are found in polluted water, but they can also occur naturally in groundwater.

27. Water Treatment
Pathogen – a virus, microorganism, or other substance that causes disease
Pathogens are found in water contaminated by sewage or animal feces, but can be removed with water treatment.

29. Industrial Water Use
Industry accounts for 19 percent of water used in the world. Water is used to manufacture goods, to dispose of wastes, and to generate power.

30. Industrial Water Use
Most of the water that is used in industry is used to cool power plants.
Power-plant cooling systems usually pump water from a surface water source such as a river or a lake, carry the water through pipes in a cooling tower, and then pump the water back into the source.
The water that is returned is usually warmer than the source, but is generally clean and can be used again.

31. Agricultural Water Use
Agriculture accounts for 67 percent of the water used in the world. Plants require a lot of water to grow, and as much as 80 percent of the water used in agriculture evaporates.

32. Agricultural Water Use
Irrigation – a method of providing plants with water from sources other than direct precipitation

33. Agricultural Water Use
In the U.S., high-pressured overhead sprinklers are the most common form of irrigation. However, this method is inefficient because nearly half the water evaporates and never reaches the plant roots.

34. Dams and Reservoirs
Dam – a structure that is built across a river to control a river’s flow
Interrupting a river’s flow can have consequences. For example, when the land behind a dam is flooded, people are displaced, and entire ecosystems can be destroyed.

35. Dams and Reservoirs
Reservoir – an artificial body of water that usually forms behind a dam
Water from a reservoir can be used for flood control, drinking water, irrigation, recreation, and industry.

36. Water Conservation in Agriculture
Most of the water loss in agriculture comes from evaporation, seepage, and runoff. Drip irrigation systems deliver small amounts of water directly to plant roots by using perforated tubing.

37. Water Conservation at Home

38. Solutions for the Future
Desalination – the process of removing salt from ocean water
Some countries in drier parts of the world, such as the Middle East, have built desalination plants to provide fresh water.
Because desalination consumes a lot of energy, the process is too expensive for many nations to consider.
Desalination plant in Kuwait

39. 11-3: Water Pollution

40. Water Pollution
Water pollution – the introduction into water of waste matter or chemicals that are harmful to organisms living in the water or to those that drink or are exposed to the water
Water pollution comes from two types of sources: point and nonpoint sources.

41. Water Pollution
Point-source pollution – pollution that comes from a specific site
Examples: such as a factory, a wastewater treatment plant, or a leaking oil tanker

42. Chapter 11
Section 3 Water Pollution
Oil Spills

43. Water Pollution
Non-point source pollution – pollution that comes from many sources rather than from a single specific site
Example: pollution that reaches a body of water from streets and storm sewers

44. Groundwater Pollution
Chapter 11
Section 3 Water Pollution
Groundwater Pollution

47. Wastewater

48. Artificial Eutrophication
Artificial eutrophication – a process that increases the amount of nutrients in a body of water through human activities, such as waste disposal and land drainage
A major cause of this is fertilizer runoff

49. Water Pollution and Ecosystems
Chapter 11
Section 3 Water Pollution
Water Pollution and Ecosystems

50. Clean Water Act
Beginning with the industrial revolution and continuing into the 1960s, water pollution was seen as a necessary consequence of growth and industry.
In 1969, the Cuyahoga River in Ohio caught fire, due to a buildup of oil on its surface.
Articles in Time Magazine and National Geographic spurred a movement that gave birth the first water pollution laws.
Cuyahoga River fire, 1952.

51. By 1972, about two-thirds of U. S
By 1972, about two-thirds of U.S. lakes, rivers, and coastal waters were unsafe for swimming and fishing.
The Clean Water Act, passed in 1977, is a law that set the allowable limits for various pollutants in surface waters.
Any point source may not discharge pollution into surface waters without a permit.
States are required to develop lists of impaired waters that are too polluted or degraded to meet water quality standards.

52. The damage was worsened by a series of other factors:
When the Exxon Valdez ran aground in Alaska, a high volume of oil was spilled.
The damage was worsened by a series of other factors:
The remoteness of the spill’s location.
A delayed cleanup response due to a lack of preparation by the oil companies.

53. Operators of oil tankers are responsible for all cleanup costs.
Following the Exxon Valdez spill, the Oil Pollution Act of 1990 made the following changes:
Operators of oil tankers are responsible for all cleanup costs.
Increased the maximum liability for losses by businesses and private individuals.
Phased out single-hulled tankers in favor of double-hulled tankers.
Reduces losses in an oil spill by 4-6 times.

54. Deepwater Horizon
The worst oil spill by volume occurred in 2010 when an oil rig in the Gulf of Mexico experienced a blowout.
The drilled well at the bottom of the sea gushed nearly 5 million barrels of oil into the sea over a period of four months.