Geos109 lect10 water Adobe PDF Reader & WinZip, Education

1. Water and Water Pollution

2. Case Study: Water Conflicts
 Water shortages in the Middle East
 Nile River
 Jordan Basin
 Tigris and Euphrates Rivers

3. Three Major River Basins
in the Middle East

4. Will We Have Enough Water?
 We are using available freshwater unsustainably
• wasting it
• polluting it
• charging too little for this irreplaceable natural
resource.
 One of every six people do not have sufficient
access to clean water, and this situation will
almost certainly get worse.

5. Importance and Availability of Water
 Why is water so important?
 Earth as a watery world – 71%
 Freshwater availability – 0.024%
 Poorly managed resource
 Hydrologic cycle
 Water pollution

6. Confining impermeable rock layer
Less
permeable material
such as clay
Stream
Well
requiring
a pump Lake
Unconfined aquifer
Flowing
artesian well
Runoff
Confined
Recharge
Area
Water
table
Confined aquifer
Infiltration
EvaporationEvaporation and transpiration
Infiltration
Unconfined Aquifer Recharge Area
Recharge
Unconfined Aquifer
Precipitation

7. Groundwater
 Zone of saturation
 Water table
 Aquifers
 Natural recharge

8. Surface Water
 Surface runoff
 Watershed (drainage) basin
 Reliable runoff – 1/3 of total
 Runoff use
• Domestic – 10%
• Agriculture – 70%
• Industrial use – 20%

9. Case Study: Freshwater Resources in the
United States
 Uneven distribution
 Contamination
 Eastern U.S.
 Western U.S.
 Groundwater withdrawal – 50%

10. Stepped Art
Average annual precipitation (centimeters)
Less than 41
41-81
81-122
More than 122
Acute shortage
Shortage
Adequate supply
Metropolitan regions with population greater than 1 million

11. Water Hot Spots in Western States

12. Freshwater Shortages
 Causes of water scarcity
• Dry climate
• Too many people
 1 of 6 people – no regular access to clean water
• Over one billion have no access to improved
drinking water
• According to the U.N. children's agency UNICEF,
polluted water and lack of basic sanitation claim
the lives of over 1.5 million children every year,
mostly from water-borne diseases.

13. While most people living in
Western Europe can access
safe water, only 50% of
people living in Central Africa
can do this. The largest
population without access to
safe tap water is in China
(25%)
waterwiki.net/index.php/Unsafe_Water

14. Stress on World’s River Basins

15. How Can We Increase Water Supplies?
 Groundwater used to supply cities and grow
food is being pumped from aquifers in some
areas faster than it is renewed by precipitation.
 Using dams, reservoirs, and transport systems
to transfer water to arid regions has increased
water supplies in those areas, but has disrupted
ecosystems and displaced people.

16. How Can We Increase Water Supplies?
 We can convert salty ocean water to freshwater,
but the cost is high, and the resulting salty brine
must be disposed of without harming aquatic or
terrestrial ecosystems.

17. Increasing Freshwater Supplies
 Withdrawing groundwater
 Dams and reservoirs
 Transporting surface water
 Desalination
 Water conservation
 Better use of natural hydrologic cycle

18. Aquifer Depletion from Groundwater
Overdraft in the United States

19. Saltwater Intrusion into
Coastal Water Wells

20. Trade-offs of Large Dams and Reservoirs

21. California Water Project and Central
Arizona Project

22. Aral Sea Disaster
 Large-scale water transfers in dry central Asia
 Salinity
 Wetland destruction and wildlife
 Fish extinctions and fishing

23. Aral Sea Disaster
 Wind-blown salt
 Water pollution
 Climatic changes
 Restoration efforts

24. Shrinking Aral Sea

25. Removing Salt from Seawater
 Desalination
 Distillation
 Reverse osmosis
 15,000 plants in 125 countries

26. Major Problems with Desalination
 High cost
 Death of marine organisms
 Large quantity of brine wastes
 Future economics

27. Ashkelon Plant supplies 15%
of Israel’s Households
water needs-
Largest plant in 2005

28. How Can We Use Water More
Sustainably?
 We can use water more sustainably by cutting
water waste, raising water prices, slowing
population growth, and protecting aquifers,
forests, and other ecosystems that store and
release water.

29. Reducing Water Waste (1)
 Benefits of water conservation
 Worldwide – 65-70% loss
• Evaporation, leaks
 Water prices, government subsides, waste

30. Reducing Water Waste (2)
 Improve irrigation efficiency
 Improve collection efficiency
 Use less in homes and businesses

31. Major Irrigation Systems

32. Reducing Irrigation Water Waste

33. Reducing Water Waste

34. Sustainable Water Use

35. What Can You Do?

36. How Can We Reduce the Threat of
Flooding?
 We can improve flood control by protecting more
wetlands and natural vegetation in watersheds
and by not building in areas subject to frequent
flooding.

37. Benefits of Floodplains (1)
 Highly productive wetlands
 Provide natural flood and erosion control
 Maintain high water quality
 Recharge groundwater

38. Benefits of Floodplains (2)
 Fertile soils
 Nearby rivers for use and recreation
 Flatlands for urbanization and farming

39. Dangers of Floodplains and Floods
 Deadly and destructive
 Human activities worsen floods
 Failing dams and water diversion
 Hurricane Katrina and the Gulf Coast
• Removal of coastal wetlands

40. Before and During a Flood in
St. Louis, Missouri

41. Case Study: Floodplains of Bangladesh
 Dense population
 Located on coastal floodplain
 Moderate floods maintain fertile soil
 Increase frequency of large floods
 Development in the Himalayan foothills
 Destruction of coastal wetlands

42. Hillside Before and After Deforestation

43. Reducing Flood Damage

44. How Can We Best Deal with Water
Pollution? (1)
 Streams can cleanse themselves of many
pollutants if we do not overload them.
 Preventing water pollution usually works better
and costs less than trying to clean it up.

45. How Can We Best Deal with Water
Pollution? (2)
 Reducing water pollution requires preventing it,
working with nature in treating sewage, cutting
resource use and waste, reducing poverty, and
slowing population growth.

46. Water Pollution Sources
 Water pollution
 Point sources
• Discharge at specific locations
• Easier to identify, monitor, regulate
 Nonpoint sources
• Runoff of chemicals and sediment
• Agriculture
• Control is difficult and expensive

47. Major Water Pollutants and Their
Sources

48. Pollution in Streams

49. Lake Pollution (1)
 Dilution less effective than with streams
• Stratification
• Low flow
 Lakes are more vulnerable than streams
 Eutrophication – natural aging process
• Oligotrophic

50. Oligotrophic and Eutrophic Lakes

51. Groundwater Pollution (1)
 Sources
 Slow flow, dilution, dispersion
 Low dissolved oxygen
 Fewer bacteria
 Cooler temperatures

52. Groundwater Pollution (2)
 Longtime scale for natural cleansing
• Degradable wastes – organic matter
• Slowly degradable wastes – DDT
• Nondegradable wastes – lead, arsenic, fluoride

53. Sources of Groundwater Pollution

54. Extent of Groundwater Pollution
 Global scale – not much known
 Monitoring is very expensive
 Underground fuel tank leakage
• MTBE
 Arsenic
 Protecting groundwater – prevention is best!

55. Preventing and Cleaning Up
Groundwater Pollution

56. Ocean Pollution
 Coastal areas – highly productive ecosystems
• Occupied by 40% of population
• Twice that population by 2050
• About 80% marine pollution originates on land
 Deep ocean waters
• Some capacity to dilute, disperse, degrade
pollutants
• Ocean dumping controversies
• Assimilative capacity?

57. Coastal Water Pollution

58. Science Focus: Oxygen Depletion in the
Northern Gulf of Mexico

59. Oil Pollution in Oceans
 Crude and refined petroleum
 Tanker accidents – Exxon Valdez
 Urban and industrial runoff

60. Effects of Oil Pollution on Ocean
Ecosystems
 Volatile organic hydrocarbons
• Kill larvae
• Destroys natural insulation and buoyancy
 Heavy oil
• Sinks and kills bottom organisms
• Coral reefs die

61. Oil Cleanup Methods
 Current methods recover no more than 15%
 Prevention is most effective method
• Control runoff
• Double haul tankers

62. Preventing and Cleaning Up Pollution in
Coastal Waters

63. Preventing Nonpoint Source Pollution (1)
 Mostly agricultural waste
 Use vegetation to reduce soil erosion
 Reduce fertilizer use

64. Preventing Nonpoint Source Pollution (2)
 Use plant buffer zones around fields and animal
feedlots
 Keep feedlots away from slopes, surface water
and flood zones
 Integrated pest management

65. Laws for Reducing Point Source
Pollution
 Clean Water Act
 Water Quality Act
 Discharge trading controversies

66. Sewage Treatment Systems
 Rural and suburban areas – septic tank
 Urban areas – wastewater treatment plants
• Primary treatment – physical process
• Secondary treatment – biological process
• Chlorination – bleaching and disinfection

67. Primary and Secondary Sewage
Treatment

68. Improving Sewage Treatment
 Systems that exclude hazardous waste
 Nonhazardous waste substitutes
 Composting toilet systems

69. Reducing Water Pollution from Point
Sources in the U.S.
 Impressive achievements
 Bad news – 2006 survey
• 45% of lakes and 40% of streams too polluted for
fishing and swimming
• Runoff polluting 7 of 10 rivers
• Fish caught in 1/4 of waterways unsafe to eat

70. Should the Clean Water Act be
Strengthened?
 Yes – environmentalists
 No – farmers and developers
 State and local officials want more discretion

71. Drinking Water Quality
 Purification of urban drinking water
 Developed versus developing countries

72. Is Bottled Water the Answer?
 120 to 7,500 times the cost of tap water
 About 1/4 is ordinary tap water
 About 40% of bottled water contaminated
 Water testing
 Water purifiers

73. Methods for Preventing and Reducing
Water Pollution

74. What Can We Do?