Water

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1. WATERWATER
Done by uzmaDone by uzma

2. Chapter Overview QuestionsChapter Overview Questions
Why is water so important, how much Why is water so important, how much
freshwater is available to us, and how much freshwater is available to us, and how much
of it are we using?of it are we using?
What causes freshwater shortages, and what What causes freshwater shortages, and what
can be done about this problem?can be done about this problem?
What are the advantages and disadvantages What are the advantages and disadvantages
of withdrawing groundwater?of withdrawing groundwater?
What are the advantages and disadvantages What are the advantages and disadvantages
of using dams and reservoirs to supply more of using dams and reservoirs to supply more
water?water?

3. Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)
What are the advantages and disadvantages What are the advantages and disadvantages
of transferring large amounts of water from of transferring large amounts of water from
one place to another?one place to another?
Can removing salt from seawater solve our Can removing salt from seawater solve our
water supply problems?water supply problems?
How can we waste less water?How can we waste less water?
How can we use the earth’s water more How can we use the earth’s water more
sustainably?sustainably?
What causes flooding, and what can we do What causes flooding, and what can we do
about it?about it?

4. Updates OnlineUpdates Online
The latest references for topics covered in this section can be found at The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles. www.thomsonedu.com to access InfoTrac articles.
InfoTrac: For money or for life. Jeff Conant. InfoTrac: For money or for life. Jeff Conant. Earth Island JournalEarth Island Journal, Autumn , Autumn
2006 v21 i3 p33(6).2006 v21 i3 p33(6).
InfoTrac: Backstory: Tapping the world. InfoTrac: Backstory: Tapping the world. The Christian Science MonitorThe Christian Science Monitor
March 22, 2006 p20.March 22, 2006 p20.
InfoTrac: A water crisis in the making. Christopher Meyer. InfoTrac: A water crisis in the making. Christopher Meyer. Middle East Middle East
Economic DigestEconomic Digest, April 7, 2006 v50 i14 p47(2)., April 7, 2006 v50 i14 p47(2).
Science Daily: Historic Colorado River Streamflows Reconstructed Back Science Daily: Historic Colorado River Streamflows Reconstructed Back
To 1490To 1490
National GeographicNational Geographic: Map: Middle East Natural Resources: Map: Middle East Natural Resources
Science Daily: Putting Coal Ash Back Into Mines A Viable Option For Science Daily: Putting Coal Ash Back Into Mines A Viable Option For
Disposal, But Risks Must Be AddressedDisposal, But Risks Must Be Addressed

5. Video: Western DroughtVideo: Western Drought
This video clip is available in CNN Today This video clip is available in CNN Today
Videos for Environmental Science, 2004, Videos for Environmental Science, 2004,
Volume VII. Instructors, contact your local Volume VII. Instructors, contact your local
sales representative to order this volume, sales representative to order this volume,
while supplies last.while supplies last.

6. Core Case Study: Water Conflicts in Core Case Study: Water Conflicts in
the Middle East - A Preview the Middle East - A Preview
of the Futureof the Future
Many countries in Many countries in
the Middle East, the Middle East,
which has one of which has one of
the world’s highest the world’s highest
population growth population growth
rates, face water rates, face water
shortages.shortages.
Figure 14-1Figure 14-1

7. Water Conflicts in the Middle East: A Water Conflicts in the Middle East: A
Preview of the FuturePreview of the Future
Most water in this dry region comes from the Most water in this dry region comes from the
Nile, Jordan or Tigris rivers.Nile, Jordan or Tigris rivers.
Countries are in disagreement as to who has Countries are in disagreement as to who has
water rights.water rights.
Currently, there are no cooperative Currently, there are no cooperative
agreements for use of 158 of the world’s 263 agreements for use of 158 of the world’s 263
water basins that are shared by two or more water basins that are shared by two or more
countries.countries.

8. WATER’S IMPORTANCE, WATER’S IMPORTANCE,
AVAILABILITY, AND RENEWALAVAILABILITY, AND RENEWAL
Water keeps us alive, moderates climate, Water keeps us alive, moderates climate,
sculpts the land, removes and dilutes wastes sculpts the land, removes and dilutes wastes
and pollutants, and moves continually and pollutants, and moves continually
through the hydrologic cycle.through the hydrologic cycle.
Only about 0.02% of the earth’s water supply Only about 0.02% of the earth’s water supply
is available to us as liquid freshwater.is available to us as liquid freshwater.

9. WATER’S IMPORTANCE, WATER’S IMPORTANCE,
AVAILABILITY, AND RENEWALAVAILABILITY, AND RENEWAL
Comparison of Comparison of
population sizes and population sizes and
shares of the world’s shares of the world’s
freshwater among freshwater among
the continents.the continents.
Figure 14-2Figure 14-2

10. Fig. 14-2, p. 307
Continent
Percent of world's water resources
and population
Asia
60.5%
36%
Africa
10%
8%
Europe
North and Central
America 7.3%
South America and
Caribbean 6.4%
26%
15%
5%
Oceania
11.3%
0.5%
14%

11. WATER’S IMPORTANCE, WATER’S IMPORTANCE,
AVAILABILITY, AND RENEWALAVAILABILITY, AND RENEWAL
Some precipitation infiltrates the ground and Some precipitation infiltrates the ground and
is stored in soil and rock (groundwater).is stored in soil and rock (groundwater).
Water that does not sink into the ground or Water that does not sink into the ground or
evaporate into the air runs off (surface runoff) evaporate into the air runs off (surface runoff)
into bodies of water.into bodies of water.

The land from which the surface water drains into The land from which the surface water drains into
a body of water is called its a body of water is called its watershedwatershed or or
drainage basindrainage basin..

12. Fig. 14-3, p. 308
Unconfined Aquifer Recharge Area
Precipitation Evaporation and transpirationEvaporation
Confined
Recharge
Area
Runoff
Flowing
artesian
well
Recharge Recharge
Unconfined Unconfined
AquiferAquifer
Stream Well
requiring a
pumpInfiltrationWater
table Lake
Infiltration
Unconfined aquifer
Confined aquifer
Confining impermeable rock layer
Confining impermeable rock layer
Less permeable
Less permeable
material such as clay
material such as clay

13. WATER’S IMPORTANCE, WATER’S IMPORTANCE,
AVAILABILITY, AND RENEWALAVAILABILITY, AND RENEWAL
We currently use more than half of the We currently use more than half of the
world’s reliable runoff of surface water and world’s reliable runoff of surface water and
could be using 70-90% by 2025.could be using 70-90% by 2025.
About 70% of the water we withdraw from About 70% of the water we withdraw from
rivers, lakes, and aquifers is not returned to rivers, lakes, and aquifers is not returned to
these sources.these sources.
Irrigation is the biggest user of water (70%), Irrigation is the biggest user of water (70%),
followed by industries (20%) and cities and followed by industries (20%) and cities and
residences (10%).residences (10%).

14. Water in the Water in the
United StatesUnited States
Average Average
precipitation (top) precipitation (top)
in relation to in relation to
water-deficit water-deficit
regions and their regions and their
proximity to proximity to
metropolitan areas metropolitan areas
(bottom).(bottom).
Figure 14-4Figure 14-4

15. Fig. 14-4a, p. 309
Average annual precipitation (centimeters)
More than 122
Less than 41 81–122
41–81

16. Fig. 14-4b, p. 309
Acute shortage
Metropolitan regions with population
greater than 1 million
Shortage
Adequate supply

17. Case Study: Freshwater Resources in Case Study: Freshwater Resources in
the United Statesthe United States
17 western states 17 western states
by 2025 could face by 2025 could face
intense conflict over intense conflict over
scarce water scarce water
needed for urban needed for urban
growth, irrigation, growth, irrigation,
recreation and recreation and
wildlife.wildlife.
Figure 14-5Figure 14-5

18. Fig. 14-5, p. 310
Wash.
Montana
Oregon
N.D.
Idaho
Wyoming S.D.
Nevada Neb.
Utah
Colo.
Kansas
California
Oak.
N.M.
Texas
Highly likely conflict potential
Moderate conflict potential
Unmet rural water needs
Substantial conflict potential

19. TOO LITTLE FRESHWATERTOO LITTLE FRESHWATER
About 41% of the world’s population lives in About 41% of the world’s population lives in
river basins that do not have enough river basins that do not have enough
freshwater.freshwater.
Many parts of the world are experiencing:Many parts of the world are experiencing:

Rivers running dry.Rivers running dry.

Lakes and seas shrinking.Lakes and seas shrinking.

Falling water tables from overpumped aquifers.Falling water tables from overpumped aquifers.

20. Stress on the World’s River BasinsStress on the World’s River Basins
Comparison of the amount of water available Comparison of the amount of water available
with the amount used by humans.with the amount used by humans.
Figure 14-6Figure 14-6

21. Fig. 14-6, p. 311
Europe
North
America
Asia
Africa
South
America
Australia
Stress
High None

22. Case Study: Who Should Own and Case Study: Who Should Own and
Manage Freshwater ResourcesManage Freshwater Resources
There is controversy over whether water There is controversy over whether water
supplies should be owned and managed by supplies should be owned and managed by
governments or by private corporations.governments or by private corporations.
European-based water companies aim to European-based water companies aim to
control 70% of the U.S. water supply by control 70% of the U.S. water supply by
buying up water companies and entering into buying up water companies and entering into
agreements with cities to manage water agreements with cities to manage water
supplies.supplies.

23. How Would You Vote?How Would You Vote?
To conduct an instant in-class survey using a classroom response To conduct an instant in-class survey using a classroom response
system, access “JoinIn Clicker Content” from the PowerLecture main system, access “JoinIn Clicker Content” from the PowerLecture main
menu for Living in the Environment. menu for Living in the Environment.
Should private companies own or manage most of Should private companies own or manage most of
the world's water resources?the world's water resources?

a. No. Democratically elected governments, which are a. No. Democratically elected governments, which are
accountable to the voters, should own and manage water accountable to the voters, should own and manage water
resources.resources.

b. Qualified yes. Governments should own the water, but b. Qualified yes. Governments should own the water, but
expert private companies should manage it.expert private companies should manage it.

c. Depends. Each case must be decided independently. c. Depends. Each case must be decided independently.
The record on private versus public ownership is mixed.The record on private versus public ownership is mixed.

d. Yes. Private companies have more expertise and d. Yes. Private companies have more expertise and
experience in managing water resources than most experience in managing water resources than most
government bureaucrats. government bureaucrats.

24. TOO LITTLE FRESHWATERTOO LITTLE FRESHWATER
Cities are outbidding farmers for water Cities are outbidding farmers for water
supplies from rivers and aquifers.supplies from rivers and aquifers.
Countries are importing grain as a way to Countries are importing grain as a way to
reduce their water use.reduce their water use.
More crops are being used to produce More crops are being used to produce
biofuels.biofuels.
Our water options are:Our water options are:

Get more water from aquifers and rivers, Get more water from aquifers and rivers,
desalinate ocean water, waste less water.desalinate ocean water, waste less water.

25. WITHDRAWING GROUNDWATER WITHDRAWING GROUNDWATER
TO INCREASE SUPPLIESTO INCREASE SUPPLIES
Most aquifers are renewable resources Most aquifers are renewable resources
unless water is removed faster than it is unless water is removed faster than it is
replenished or if they are contaminated.replenished or if they are contaminated.
Groundwater depletion is a growing problem Groundwater depletion is a growing problem
mostly from irrigation.mostly from irrigation.

At least one-fourth of the farms in India are being At least one-fourth of the farms in India are being
irrigated from overpumped aquifers.irrigated from overpumped aquifers.

26. Fig. 14-7, p. 313
Trade-Offs
Withdrawing Groundwater
Advantages Disadvantages
Useful for drinking
and irrigation
Aquifer depletion from
overpumping
Available year-
round
Sinking of land
(subsidence) from
overpumping
Exists almost
everywhere
Polluted aquifers for
decades or centuries
Renewable if not
overpumped or
contaminated
Saltwater intrusion into
drinking water supplies
near coastal areas
Reduced water flows
into surface waters
No evaporation
losses
Cheaper to extract
than most surface
waters
Increased cost and
contamination from
deeper wells

27. Groundwater Depletion: Groundwater Depletion:
A Growing ProblemA Growing Problem
The Ogallala, the world’s largest aquifer, is The Ogallala, the world’s largest aquifer, is
most of the red area in the center (Midwest).most of the red area in the center (Midwest).
Areas of Areas of
greatest aquifer greatest aquifer
depletion from depletion from
groundwater groundwater
overdraft in the overdraft in the
continental U.S.continental U.S.
Figure 14-8Figure 14-8

28. Fig. 14-8, p. 314
Groundwater Overdrafts:
High
Moderate
Minor or none

29. Other Effects of Groundwater Other Effects of Groundwater
OverpumpingOverpumping
Groundwater Groundwater
overpumping can overpumping can
cause land to sink, cause land to sink,
and contaminate and contaminate
freshwater aquifers freshwater aquifers
near coastal areas near coastal areas
with saltwater.with saltwater.
Figure 14-11Figure 14-11

30. Fig. 14-11, p. 315
Major
irrigation
well
Well contaminated
with saltwater
Water
table
Fresh
groundwater
aquifer
Sea level
S
altw
ater
Interface
S
eafloo
r
Saltwater
intrusion
Interface
Normal
interface

31. Other Effects of Groundwater Other Effects of Groundwater
OverpumpingOverpumping
Sinkholes form when Sinkholes form when
the roof of an the roof of an
underground cavern underground cavern
collapses after being collapses after being
drained of drained of
groundwater.groundwater.
Figure 14-10Figure 14-10

32. Groundwater Pumping in Saudi Groundwater Pumping in Saudi
Arabia (1986 – 2004)Arabia (1986 – 2004)
Irrigation systems from the nonrenewable Irrigation systems from the nonrenewable
aquifer appear as green dots. Brown dots are aquifer appear as green dots. Brown dots are
wells that have gone dry.wells that have gone dry.
Figure 14-9Figure 14-9

33. Fig. 14-12, p. 316
Solutions
Groundwater Depletion
Prevention Control
Waste less water Raise price of water
to discourage waste
Subsidize water
conservation
Ban new wells in
aquifers near
surface waters
Tax water pumped
from wells near
surface waters
Buy and retire
groundwater
withdrawal rights
in critical areas
Do not grow water-
intensive crops in
dry areas
Set and enforce
minimum stream
flow levels

34. USING DAMS AND RESERVOIRS USING DAMS AND RESERVOIRS
TO SUPPLY MORE WATERTO SUPPLY MORE WATER
Large dams and reservoirs can produce Large dams and reservoirs can produce
cheap electricity, reduce downstream cheap electricity, reduce downstream
flooding, and provide year-round water for flooding, and provide year-round water for
irrigating cropland, but they also displace irrigating cropland, but they also displace
people and disrupt aquatic systems.people and disrupt aquatic systems.

35. Figure 14-13Figure 14-13

36. Fig. 14-13a, p. 317
Provides water
for year-round
irrigation of
cropland
Flooded land
destroys forests
or cropland and
displaces people
Large losses of
water through
evaporation
Provides
water for
drinking
Downstream
cropland and
estuaries are
deprived of
nutrient-rich silt
Reservoir is
useful for
recreation
and fishing
Risk of
failure and
devastating
downstream
flooding
Can produce
cheap
electricity
(hydropower)
Downstream
flooding is
reduced
Migration and
spawning of
some fish are
disrupted

37. Fig. 14-13b, p. 317
Powerlines
Reservoir
Dam
Powerhouse
Intake
Turbine

38. Case Study: The Colorado Basin – an Case Study: The Colorado Basin – an
Overtapped ResourceOvertapped Resource
The Colorado River has so many dams and The Colorado River has so many dams and
withdrawals that it often does not reach the withdrawals that it often does not reach the
ocean.ocean.

14 major dams and reservoirs, and canals.14 major dams and reservoirs, and canals.

Water is mostly used in desert area of the U.S.Water is mostly used in desert area of the U.S.

Provides electricity from hydroelectric plants for Provides electricity from hydroelectric plants for
30 million people (1/1030 million people (1/10
thth
of the U.S. population). of the U.S. population).

39. Case Study: The Colorado Basin – an Case Study: The Colorado Basin – an
Overtapped ResourceOvertapped Resource
Lake Powell, is Lake Powell, is
the second the second
largest reservoir largest reservoir
in the U.S.in the U.S.
It hosts one of It hosts one of
the hydroelectric the hydroelectric
plants located on plants located on
the Colorado the Colorado
River.River.
Figure 14-15Figure 14-15

40. The Colorado River BasinThe Colorado River Basin
The area The area
drained by this drained by this
basin is equal to basin is equal to
more than one-more than one-
twelfth of the twelfth of the
land area of the land area of the
lower 48 states.lower 48 states.
Figure 14-14Figure 14-14

41. Fig. 14-14, p. 318
Dam
Aqueduct or
canal
Upper Basin
LOWER
BASIN
0 100 mi.
0 150 km
Lower Basin
UPPER
BASIN
IDAHO
WYOMING
Salt Lake City
Grand Junction
Denver
UTAH
NEVADA
COLORADOLake
Powell
Las Vegas
Grand
Canyon
Glen
Canyon Dam
Boulder City
NEW MEXICO
ARIZONALos
Angeles
Albuquerque
Phoenix
San
Diego
Mexicali
Yuma
Tucson
All-American
Canal
Gulf of
California
MEXICO
CALIFORNIA
Palm
Springs
C
o
lo
ra
d
o

R
iv
e
r

42. How Would You Vote?How Would You Vote?
To conduct an instant in-class survey using a classroom response To conduct an instant in-class survey using a classroom response
system, access “JoinIn Clicker Content” from the PowerLecture main system, access “JoinIn Clicker Content” from the PowerLecture main
menu for Living in the Environment. menu for Living in the Environment.
Do the advantages of large dams outweigh Do the advantages of large dams outweigh
their disadvantages?their disadvantages?

a. No. Large dams inflict extensive environmental a. No. Large dams inflict extensive environmental
damage and humans must learn to meet their damage and humans must learn to meet their
needs without them.needs without them.

b. Yes. Dams are critical in providing water and b. Yes. Dams are critical in providing water and
electricity for people, especially in developing electricity for people, especially in developing
countries. countries.

43. Case Study: Case Study:
China’s Three Gorges DamChina’s Three Gorges Dam
There is a debate over whether the There is a debate over whether the
advantages of the world’s largest dam and advantages of the world’s largest dam and
reservoir will outweigh its disadvantages.reservoir will outweigh its disadvantages.

The dam will be 2 kilometers long.The dam will be 2 kilometers long.

The electric output will be that of 18 large coal-The electric output will be that of 18 large coal-
burning or nuclear power plants.burning or nuclear power plants.

It will facilitate ship travel reducing transportation It will facilitate ship travel reducing transportation
costs.costs.

Dam will displace 1.2 million people.Dam will displace 1.2 million people.

Dam is built over seismatic fault and already has Dam is built over seismatic fault and already has
small cracks. small cracks.

44. Dam RemovalDam Removal
Some dams are being removed for ecological Some dams are being removed for ecological
reasons and because they have outlived their reasons and because they have outlived their
usefulness.usefulness.

In 1998 the U.S. Army Corps of Engineers In 1998 the U.S. Army Corps of Engineers
announced that it would no longer build large announced that it would no longer build large
dams and diversion projects in the U.S.dams and diversion projects in the U.S.

The Federal Energy Regulatory Commission has The Federal Energy Regulatory Commission has
approved the removal of nearly 500 dams.approved the removal of nearly 500 dams.

Removing dams can reestablish ecosystems, but Removing dams can reestablish ecosystems, but
can also re-release toxicants into the can also re-release toxicants into the
environment.environment.

45. TRANSFERRING WATER FROM TRANSFERRING WATER FROM
ONE PLACE TO ANOTHERONE PLACE TO ANOTHER
Transferring water can make unproductive Transferring water can make unproductive
areas more productive but can cause areas more productive but can cause
environmental harm.environmental harm.

Promotes investment, jobs and strong economy.Promotes investment, jobs and strong economy.

It encourages unsustainable use of water in It encourages unsustainable use of water in
areas water is not naturally supplied.areas water is not naturally supplied.

46. Case Study: The California ExperienceCase Study: The California Experience
A massive A massive
transfer of water transfer of water
from water-rich from water-rich
northern northern
California to California to
water-poor water-poor
southern southern
California is California is
controversial.controversial.
Figure 14-16Figure 14-16

47. Fig. 14-16, p. 321
CALIFORNIA
Sacramento
River
North Bay
Aqueduct
Lake Tahoe
San Francisco
Sacramento
South Bay
Aqueduct
Hoover Dam and
Reservoir (Lake
Mead)
NEVADA
UTAH
Fresno
San Luis Dam
and Reservoir
Los Angeles
Aqueduct
Colorado
River
California Aqueduct
Santa Barbara
Colorado River
Aqueduct Central Arizona
Project
ARIZONA
Los Angeles
Salton Sea
PhoenixSan Diego
Tucson
MEXICO
S
a
n

J
o
a
q
u
i
n

V
a
l
l
e
y
Feather
River
Shasta Lake
Oroville Dam and
Reservoir

48. Case Study: The Aral Sea DisasterCase Study: The Aral Sea Disaster
The Aral Sea was once the world’s fourth The Aral Sea was once the world’s fourth
largest freshwater lake.largest freshwater lake.
Figure 14-17Figure 14-17

49. Case Study: The Aral Sea DisasterCase Study: The Aral Sea Disaster
Diverting water from the Aral Sea and its two Diverting water from the Aral Sea and its two
feeder rivers mostly for irrigation has feeder rivers mostly for irrigation has
created a major ecological, economic, and created a major ecological, economic, and
health disaster.health disaster.

About 85% of the wetlands have been About 85% of the wetlands have been
eliminated and roughly 50% of the local bird and eliminated and roughly 50% of the local bird and
mammal species have disappeared.mammal species have disappeared.

Since 1961, the sea’s salinity has tripled and the Since 1961, the sea’s salinity has tripled and the
water has dropped by 22 meters most likely water has dropped by 22 meters most likely
causing 20 of the 24 native fish species to go causing 20 of the 24 native fish species to go
extinct.extinct.

50. DESALTING SEAWATER, SEEDING DESALTING SEAWATER, SEEDING
CLOUDS, AND TOWING ICEBERGS CLOUDS, AND TOWING ICEBERGS
AND GIANT BAGGIESAND GIANT BAGGIES
Removing salt from seawater by current Removing salt from seawater by current
methods is expensive and produces large methods is expensive and produces large
amounts of salty wastewater that must be amounts of salty wastewater that must be
disposed of safely.disposed of safely.

DistillationDistillation: heating saltwater until it evaporates, : heating saltwater until it evaporates,
leaves behind water in solid form.leaves behind water in solid form.

Reverse osmosisReverse osmosis: uses high pressure to force : uses high pressure to force
saltwater through a membrane filter.saltwater through a membrane filter.

51. DESALTING SEAWATER, SEEDING DESALTING SEAWATER, SEEDING
CLOUDS, AND TOWING ICEBERGS CLOUDS, AND TOWING ICEBERGS
AND GIANT BAGGIESAND GIANT BAGGIES
Seeding clouds with tiny particles of Seeding clouds with tiny particles of
chemicals to increase rainfall towing icebergs chemicals to increase rainfall towing icebergs
or huge bags filled with freshwater to dry or huge bags filled with freshwater to dry
coastal areas have all been proposed but are coastal areas have all been proposed but are
unlikely to provide significant amounts of unlikely to provide significant amounts of
freshwater.freshwater.

52. INCREASING WATER SUPPLIES BY INCREASING WATER SUPPLIES BY
WASTING LESS WATERWASTING LESS WATER
We waste about two-thirds of the water we We waste about two-thirds of the water we
use, but we could cut this waste to 15%.use, but we could cut this waste to 15%.

65-70% of the water people use throughout the 65-70% of the water people use throughout the
world is lost through evaporation, leaks, and world is lost through evaporation, leaks, and
other losses.other losses.

Water is underpriced through government Water is underpriced through government
subsidies.subsidies.

The lack of government subsidies for improving The lack of government subsidies for improving
the efficiency of water use contributes to water the efficiency of water use contributes to water
waste.waste.

53. How Would You Vote?How Would You Vote?
To conduct an instant in-class survey using a classroom response To conduct an instant in-class survey using a classroom response
system, access “JoinIn Clicker Content” from the PowerLecture main system, access “JoinIn Clicker Content” from the PowerLecture main
menu for Living in the Environment.menu for Living in the Environment.
Should water prices be raised sharply to help Should water prices be raised sharply to help
reduce water waste?reduce water waste?

a. No. Poor people, farmers, ranchers, and small a. No. Poor people, farmers, ranchers, and small
businesses would suffer from price increases. businesses would suffer from price increases.

b. Yes. People would be more likely to conserve b. Yes. People would be more likely to conserve
water if it is more expensive. water if it is more expensive.

54. INCREASING WATER SUPPLIES BY INCREASING WATER SUPPLIES BY
WASTING LESS WATERWASTING LESS WATER
Sixty percent of the world’s irrigation water is Sixty percent of the world’s irrigation water is
currently wasted, but improved irrigation currently wasted, but improved irrigation
techniques could cut this waste to 5-20%.techniques could cut this waste to 5-20%.
Center-pivot, low pressure sprinklers sprays Center-pivot, low pressure sprinklers sprays
water directly onto crop.water directly onto crop.

It allows 80% of water to reach crop.It allows 80% of water to reach crop.

Has reduced depletion of Ogallala aquifer in Has reduced depletion of Ogallala aquifer in
Texas High Plains by 30%.Texas High Plains by 30%.

55. Fig. 14-18, p. 325
Center pivotCenter pivot
Drip irrigationDrip irrigation
Gravity flowGravity flow
(efficiency 60% and
80% with surge
valves)
Above- or below-
ground pipes or tubes
deliver water to
individual plant roots.
Water usually comes from
an aqueduct system or a
nearby river.
(efficiency 90–95%)
(efficiency 80%–95%)
Water usually pumped
from underground and
sprayed from mobile
boom with sprinklers.

56. Fig. 14-19, p. 326
Solutions
Reducing Irrigation Water Waste
• Line canals bringing water to irrigation
ditches
• Level fields with lasers
• Irrigate at night to reduce evaporation
• Monitor soil moisture to add water
only when necessary
• Polyculture
• Organic farming
• Don't grow water-thirsty crops in dry
areas
• Grow water-efficient crops using
drought resistant and salt-tolerant crop
varieties
• Irrigate with treated urban waste
water
• Import water-intensive crops and meat

57. Solutions: Getting More Water for Solutions: Getting More Water for
Irrigation in Developing Countries – Irrigation in Developing Countries –
The Low-Tech ApproachThe Low-Tech Approach
Many poor farmers in Many poor farmers in
developing countries developing countries
use low-tech methods use low-tech methods
to pump groundwater to pump groundwater
and make more and make more
efficient use of rainfall.efficient use of rainfall.
Figure 14-20Figure 14-20

58. Fig. 14-21, p. 327
Solutions
Reducing Water Waste
• Redesign manufacturing processes
• Repair leaking underground pipes
• Landscape yards with plants that
require little water
• Use drip irrigation
• Fix water leaks
• Use water meters
• Raise water prices
• Use waterless composting toilets
• Require water conservation in water-
short cities
• Use water-saving toilets, showerheads,
and front loading clothes washers
• Collect and reuse household water to
irrigate lawns and nonedible plants
• Purify and reuse water for houses,
apartments, and office buildings
• Don't waste energy

59. Raising the Price of Water:Raising the Price of Water:
A Key to Water Conservation A Key to Water Conservation
We can reduce water use and waste by We can reduce water use and waste by
raising the price of water while providing low raising the price of water while providing low
lifeline rates for the poor.lifeline rates for the poor.

When Boulder, Colorado introduced water When Boulder, Colorado introduced water
meters, water use per person dropped by 40%.meters, water use per person dropped by 40%.

A 10% increase in water prices cuts domestic A 10% increase in water prices cuts domestic
water use by 3-7%.water use by 3-7%.

60. Solutions: Using Less Water to Remove Solutions: Using Less Water to Remove
Industrial and Household WastesIndustrial and Household Wastes
We can mimic the way nature deals with We can mimic the way nature deals with
wastes instead of using large amounts of wastes instead of using large amounts of
high-quality water to wash away and dilute high-quality water to wash away and dilute
industrial and animal wastes.industrial and animal wastes.

Use nutrients in wastewater before treatment as Use nutrients in wastewater before treatment as
soil fertilizer.soil fertilizer.

Use waterless and odorless composting toilets Use waterless and odorless composting toilets
that convert human fecal matter into a small that convert human fecal matter into a small
amount of soil material.amount of soil material.

61. TOO MUCH WATERTOO MUCH WATER
Heavy rainfall, rapid snowmelt, removal of Heavy rainfall, rapid snowmelt, removal of
vegetation, and destruction of wetlands vegetation, and destruction of wetlands
cause flooding.cause flooding.
Floodplains, which usually include highly Floodplains, which usually include highly
productive wetlands, help provide natural productive wetlands, help provide natural
flood and erosion control, maintain high flood and erosion control, maintain high
water quality, and recharge groundwater.water quality, and recharge groundwater.
To minimize floods, rivers have been To minimize floods, rivers have been
narrowed with levees and walls, and narrowed with levees and walls, and
dammed to store water.dammed to store water.

62. TOO MUCH WATERTOO MUCH WATER
Comparison of St. Louis, Missouri under Comparison of St. Louis, Missouri under
normal conditions (1988) and after severe normal conditions (1988) and after severe
flooding (1993).flooding (1993).
Figure 14-22Figure 14-22

63. TOO MUCH WATERTOO MUCH WATER
Human activities have contributed to flood Human activities have contributed to flood
deaths and damages.deaths and damages.
Figure 14-23Figure 14-23

64. Fig. 14-23a, p. 330
Oxygen
released by
vegetation
Diverse Diverse
ecological ecological
habitathabitat
Evapotranspiration
Trees reduce soil
erosion from heavy
rain and wind
Agricultural
land
Steady
river flow
Leaf litter
improves soil
fertility
Tree roots stabilize
soil and aid water
flow
Vegetation releases
water slowly and
reduces flooding
Forested Hillside

65. Fig. 14-23b, p. 330
Tree plantation
Roads Roads
destabilize destabilize
hillsideshillsides
Evapotranspiration decreases
Ranching accelerates
soil erosion by water
and wind
Winds remove fragile
topsoil
Agricultural land is
flooded and silted up
Gullies and Gullies and
landslideslandslides
Heavy rain leaches
nutrients from soil and
erodes topsoil
Silt from erosion blocks rivers and reservoirs
and causes flooding downstream
Rapid runoff
causes flooding
After Deforestation

66. Fig. 14-24, p. 331
Solutions
Reducing Flood Damage
Prevention Control
Preserve forests on
watersheds
Strengthen and
deepen streams
(channelization)
Preserve and
restore wetlands
in floodplains
Tax all development
on floodplains
Build levees or
floodwalls along
streams
Use floodplains
primarily for
recharging aquifers,
sustainable
agriculture and
forestry, and
recreation
Build dams

67. SOLUTIONS: USING SOLUTIONS: USING
WATER MORE WATER MORE
SUSTAINABLYSUSTAINABLY
We can use water more We can use water more
sustainably by cutting sustainably by cutting
waste, raising water waste, raising water
prices, preserving prices, preserving
forests and wetlands in forests and wetlands in
water basins, and water basins, and
slowing population slowing population
growth.growth.
Figure 14-25Figure 14-25

68. Fig. 14-25, p. 333
What Can You Do?
Water Use and Waste
• Use water-saving toilets, showerheads, and faucet aerators.
• Shower instead of taking baths, and take short showers.
• Stop water leaks.
• Turn off sink faucets while brushing teeth, shaving, or washing.
• Flush toilets only when necessary.
• Wash only full loads of clothes or use the lowest water-level for
smaller loads.
• Use recycled (gray) water for lawn, gardens, house plants,
car washing.
• Wash a car from a bucket of soapy water, and use the hose for
rinsing only.
• If you use a commercial car wash, try to find one that recycles its
water.
• Replace your lawn with native plants that need little if any watering and
decorative gravel or rocks.
• Water lawns and gardens in the early morning or evening.
• Sweep or blow off driveways instead of hosing off with water.
• Use drip irrigation and mulch for gardens and flowerbeds.