good presentation on water......hope u like it!!

1. WATER
Done by uzma

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

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

4. Updates Online
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
www.thomsonedu.com to access InfoTrac articles.






InfoTrac: For money or for life. Jeff Conant. Earth Island Journal, Autumn
2006 v21 i3 p33(6).
InfoTrac: Backstory: Tapping the world. The Christian Science Monitor
March 22, 2006 p20.
InfoTrac: A water crisis in the making. Christopher Meyer. Middle East
Economic Digest, April 7, 2006 v50 i14 p47(2).
Science Daily: Historic Colorado River Streamflows Reconstructed Back
To 1490
National Geographic: Map: Middle East Natural Resources
Science Daily: Putting Coal Ash Back Into Mines A Viable Option For
Disposal, But Risks Must Be Addressed

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

26. Trade-Offs
Withdrawing Groundwater
Advantages
Disadvantages
Useful for drinking
and irrigation
Aquifer depletion from
overpumping
Available yearround
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
No evaporation
losses
Reduced water flows
into surface waters
Cheaper to extract
than most surface
waters
Increased cost and
contamination from
deeper wells
Fig. 14-7, p. 313

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

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

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

30. Major
irrigation
well
Fresh
groundwater
aquifer
Well contaminated
with saltwater
Water
table
Sea level
ea
S
Interface
Saltwater
intrusion
alt
S
ate
w
r
or
flo
Interface
Normal
interface
Fig. 14-11, p. 315

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

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

33. Solutions
Groundwater Depletion
Prevention
Waste less water
Control
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 waterintensive crops in
dry areas
Set and enforce
minimum stream
flow levels
Fig. 14-12, p. 316

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

35. Figure 14-13

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

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

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

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

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

41. IDAHO
WYOMING
Dam
Aqueduct or
canal
Upper Basin
Salt Lake City
UTAH
NEVADA
Lake
Powell
Grand
Canyon
Las Vegas
Co
Ri l o r a
ve
r do
Lower Basin
Denver
Grand Junction
UPPER
BASIN
COLORADO
Glen
Canyon Dam
NEW MEXICO
Boulder City
CALIFORNIA
Los
Angeles
ARIZONA
Palm
Springs
San
Diego
All-American
Canal
Albuquerque
LOWER
BASIN
Phoenix
Yuma
Mexicali
Gulf of
California
Tucson
0
100 mi.
0
150 km
MEXICO
Fig. 14-14, p. 318

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

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

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

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

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

47. CALIFORNIA
NEVADA
Shasta Lake
Oroville Dam and
Reservoir
Sacramento
River
UTAH
Feather
Lake Tahoe
River
North Bay
Aqueduct
San Francisco
ey
Santa Barbara
Los Angeles
Hoover Dam and
Reservoir (Lake
Mead)
Los Angeles
Aqueduct
ll
Va
California Aqueduct
Fresno
uin
aq
Jo
San Luis Dam
and Reservoir
n
Sa
South Bay
Aqueduct
Sacramento
Colorado River
Aqueduct
San Diego
Salton Sea
Colorado
River
ARIZONA
Central Arizona
Project
Phoenix
Tucson
MEXICO
Fig. 14-16, p. 321

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

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

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

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

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

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

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

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

56. 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
Fig. 14-19, p. 326

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

58. 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 watershort 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
Fig. 14-21, p. 327

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

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

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

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

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

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

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

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

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

68. 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.
Fig. 14-25, p. 333