Water Resources and Water Pollution

1
Water Resources and Water Pollution
G. Tyler Miller, Jr.s Environmental Science 10th
Edition Chapter 14
2
Key Concepts

• Unique physical properties of water

• Availability of fresh water

• Using water more efficiently

• Problems associated with flooding

• Types, sources, and effects of water pollutants

• Pollution problems of surface and ground water

• Reduction and prevention of water pollution

• Sustainable use of water

3
Water Conflicts in the Middle East

• Water shortages-
• 10 countries share
• 3 rivers

• Nile River

• Jordan Basin

• Tigris-Euphrates

Fig. 14-1, p. 305
4
Waters Unique Properties

• Hydrogen bonding

• Liquid over wide temperature range

• Changes temperature slowly

• High heat of evaporation

• Great dissolving power

• Filters out ultraviolet radiation

• High surface tension and wetting ability

• Expands when it freezes

5
Supply of Water Resources
All water
Fresh water
Readily accessible fresh water
(0.014)
Groundwater 0.592
Biota 0.0001
Rivers 0.0001
Lakes 0.007
0.014
Fresh water 2.6
Oceans and saline lakes 97.4
Ice caps and glaciers 1.984
Atmospheric water vapor 0.001
Soil moisture 0.005
Fig. 14-2, p. 307
6
Surface Water

• Surface runoff- precipitation that does not
  infiltrate or evaporate

• Reliable runoff- available for human use(not
  lost by seasonal floods)

• Watershed (drainage basin) -defined by
  topography

7
Groundwater- water that sinks into the soil and
is stored in underground reservoirs

• Zone of saturation- area where all pores in soil
  and rock are filled with water

• Water table- located at the top of zone of
  saturation. Rises and falls seasonally

• Aquifers- porous, water-saturated layers of
  sand, gravel or bedrock which groundwater flows

• Natural recharge - natural replenishment of
  aquifer by precipitation percolating downward

8
Groundwater- Moves at about 1 meter per year
Fig. 14-3, p. 308
9
Use of Water Resources

• Humans use about 55 of reliable runoffProjected
  to increase, cause conflict

• Agriculture- Uses 69 of worlds withdrawn water

• Industry - Uses 23 of worlds withdrawn water

• Domestic

10
Global Water Withdrawal (1900-2000)
11
Water Use in US and China
12
Amount of Water Needed to Produce Various Items
US per capita water use 1,280 gallons per
person per day (1999)
13
Water Problems in the US

• Shortages

Average annual precipitation (centimeters)
Less than 41
81-22

• Flooding

More than 122
41-81

• Pollution

Fig. 14-7a, p. 310
14
Water Stress Scarcity

• A country is water stressed when per capita
  availability falls below 60,000 ft3 per year (1
  swimming pool 9,000 ft3)
• A country is water scarce when per capita
  availability falls below 35,000 ft3 per year
• 500 million people live in water scarce countries
• Projection 2.4-3.4 billion people water scare or
  water stressed by 2050

15
4 Causes of Water Scarcity

• Dry climate

• Drought 21 days w/ precip. below70 of normal

• Desiccation from deforestation, overgrazing

Fig. 14-7b, p. 310

• Water stresslow water per person

16
Stress on Worlds River Basins
17
Trade-offs of Dams and Reservoirs
Fig. 14-9 p. 312
18
Ecological Services of Rivers
Fig. 14-10, p. 312
19
Trade-offs of Chinas Three Gorges Dam
Fig. 14-11, p. 313
20
Increasing Freshwater Supplies

• Dams and reservoirs

• Extracting groundwater

• Desalination- expensive what to do with salt?

• Reduce water waste- 60-70 of worlds water
  is wasted 50 USA

• Import food rather than grow it

• Import water

• Catching precipitation

21
Aral Sea Disaster

• Salinity

• Fish extinctions and fishing

• Wetland destruction and wildlife

• Wind-blown salt

• Water pollution

• Climatic changes

• Human health threats

22
Large-Scale Water Transfers And the Aral Sea
Disaster
KAZAKHSTAN
2000
ARAL SEA
1989
1960
UZBEKISTAN
TURKMENISTAN
Fig. 14-12, p. 313
23
Californias Water Problem

• 75 of Californias population lives south of
  Sacramento
• 75 of rain falls north of Sac.
• Necessitates giant maze of dams, pumps and
  aqueducts - One of worlds largest transfer
  projects

24
Transferring Water from One Place to Another

• California Water Project

Fig. 14-13, p. 314
25
Withdrawing Groundwater
Advantages
Disadvantages
Trade-offs of Groundwater Use
Aquifer depletion from overpumping Sinking of
land (subsidence) when water removed Polluted
aquifers unusable for decades or
centuries Saltwater intrusion into drinking
water supplies near coastal areas Reduced
water flows into streams, lakes, estuaries, and
wetlands Increased cost, energy use, and
contamination from deeper wells
Good source of water for drinking and
irrigation Available year- round Exists almost
everywhere Renewable if not overpumped or
contaminated No evaporation losses Cheaper to
extract than most surface waters
Fig. 14-14, p. 315
26
Aquifer Depletion- aquifers provide 25 worlds
drinking water 51 USA
27
Ground Subsidence from Overuse of Groundwater
28
Saltwater Intrusion in Coastal Water Wells
29
Solutions to Prevent or Slow Groundwater Depleti
on
Fig. 14-17, p. 316
30
Depletion of the Ogallala Aquifer
Saturated thickness of aquifer
Fig. 14-18, p. 317
31
Converting Salt Water to Fresh Water, Cloud
Seeding, and Iceberg Towing

• Distillation desalination

• Reverse osmosis desalination

• Problems with desalination

• Cloud seeding

• Iceberg towing

32
Reducing Water Waste

• Benefits of water conservation

• Reduce leakage and save water

• Government subsidies and waste

• Improve irrigation

• Using less water in homes and businesses

• Xeriscaping

33
Major Irrigation Systems
34
Reducing Waste in Irrigation
Fig. 14-20, p. 319
35
Reducing Water Waste in Industries, Homes,
and Businesses
Fig. 14-21, p. 320
36
Xeriscaping
Fig. 14-22, p. 320
37
Too Much Water Floods

• Living on floodplains

• Natural phenomena aggravated by human activities

Reservoir
Dam
Levee
Flood wall
Floodplain
Fig. 14-23, p. 322
38
Benefits of Floodplains

• Highly productive wetlands

• Fertile soils

• Nearby rivers for use and recreation

• Flatlands for structures

39
Dangers of Floodplains and Floods

• Deadly and destructive floods

• Human activities worsen floods

• Failing dams and water diversion

• Bangladesh

40
Before Deforestation
41
Disastrous Effects of Slope Deforestation
Tree plantation
Evapotranspiration decreases
Roads destabilize hillsides
Ranching accelerates soil erosion by water and
wind
Winds remove fragile topsoil
Agriculture land is flooded and silted up
Gullies and landslides
Heavy rain leaches nutrients from soil and erodes
topsoil
Rapid runoff causes flooding
Silt from erosion blocks rivers and reservoirs
and causes flooding downstream
Fig. 14-24b, p. 322
After Deforestation
42
Reducing Flood Risks

• Channelization

• Levees

• Dams

• Identify and manage flood-prone areas

43
Flood-prone Areas
44
Pollution of Streams

• Oxygen sag curve

• Factors influencing recovery

Fig. 14-27, p. 326
45
Lake Pollution

• Stratification in lakes

• Lack of water flow

• Biomagnification of contaminants

• Cultural eutrophication

46
Biological Magnification of PCBs
47
Lake Pollution
Cultural Eutrophication
Fig. 14-29, p. 329
48
Groundwater Pollution Causes and Persistence

• Low flow rates

• Few bacteria

• Low oxygen

• Cold temperatures

Hazardous waste injection well
Pesticides
Coal strip mine runoff
De-icing road salt
Buried gasoline and solvent tank
Cesspool septic tank
Pumping well
Gasoline station
Waste lagoon
Water pumping well
Sewer
Landfill
Leakage from faulty casing
Accidental spills
Discharge
Unconfined freshwater aquifer
Confined aquifer
Confined freshwater aquifer
Groundwater flow
Fig. 14-31, p. 331
49
Protecting Groundwater Resources

• Groundwater is difficult to clean

• Prevention is the answer

• Groundwater monitoring

• Leak detection systems

• Ban underground disposal of hazardous wastes

• Carefully store hazardous wastes above ground

50
Aquatic Systems Their Pollution Vulnerability
Approx. Flush/Cleaning Time
Aquatic Ecosystem
D.O. Replacement
Streams
Days to weeks
Fast
Lakes
1-100 years
Slower
100s 1000s of years for degradable waste
Groundwater
Slowest
Ocean Deep water ocean areas can dilute,
disperse, and degrade large amounts of pollutants
51
Ocean Pollution Coasts and Bays
Fig. 14-33, p. 334
52
Wastes Dumped in the Oceans

• Dredge spoils

• Sewage sludge

• Garbage

• Widespread ban on toxic and radioactive wastes

• Oil spills

53
Crude and Refined Petroleum (Oil) Spills

• Sources offshore wells, tankers, natural, and
  municipal sewers

• Effects death of organisms, loss of animal
  insulation and buoyancy, smothering

• Significant environmental and economic impacts

• Exxon Valdez

• Mechanical cleanup methods booms and skimmers

• Chemical cleanup methods coagulants and
  dispersants, burning

54
Protecting Coastal Waters from Pollution
Fig. 14-36, p. 337
55
Point and Nonpoint Sources of Water Pollution
Fig. 14-26, p. 325
56
Solutions Preventing and Reducing Surface Water
Pollution
Nonpoint Sources
Point Sources

• Reduce runoff

• Clean Water Act

• Buffer zone vegetation

• Water Quality Act

• Discharge trading?

• Reduce soil erosion

57
Should the Clean Water Act be Strengthened?

• Yes environmentalists

• No farmers, libertarians, developers

• State and local regulators want more discretion

58
Typical Septic Tank System
Fig. 14-37, p. 339

• Require suitable soils and maintenance

59
Technological Approach Sewage Treatment

• Primary sewage treatment (mechanical)- screen
  out the chunks

• Secondary sewage treatment (biological)-aerobic
  bacteria remove 90 of biodegradable oxygen
  demanding waste

• Advanced sewage treatment - chemical physical
  process that removes specific pollutants

• Sewage sludge disposal- ideal to use as compost
  if not contaminated with pathogens or toxins

60
Technological Approach Sewage Treatment

• Primary and secondary treatment

Fig. 14-38, p. 340
61
Improving Sewage Treatment

• Systems that exclude hazardous wastes

• Non-hazardous substitutes

• Collection of household hazardous wastes

• Composting toilet systems

• Working with nature

• Wastewater gardens

• Treatment with wetlands

62
Drinking Water Quality

• Purification of urban drinking water

• Maximum contaminant levels (MCLs)

• Purification of rural drinking water

• Safe Drinking Water Act Strengthen it?

• Bottled water - 33 US bottled water contaminated
  with bacteria- plastic problem

63
Achieving More Sustainable Use of Water Resources
Fig. 14-39, p. 343
64
Solutions Preventing and Reducing Water Pollution
Prevent groundwater contamination Greatly
reduce nonpoint runoff Reuse treated wastewater
for irrigation Find substitutes for toxic
pollutants Work with nature to treat sewage
Practice four R's of resource use (Refuse,
Reduce, Reuse, Recycle) Reduce resource waste
Reduce air pollution Reduce poverty Reduce
birth rates
Fig. 14-40, p. 343