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Water Resources and Water Pollution

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Water Resources and Water Pollution Chapter 11 * * * Figure 11.26 Natural capital degradation: These are the principal sources of groundwater contamination in the ... – PowerPoint PPT presentation

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Title: Water Resources and Water Pollution


1
Water Resources and Water Pollution
  • Chapter 11

2
WILL WE HAVE ENOUGH USABLE WATER?
  • Section 11-1

3
Freshwater is an irreplaceable resource that we
are managing poorly
  • Water is an irreplaceable chemical with unique
    properties that keep us and other forms of life
    alive. A person could survive for several weeks
    without food, but for only a few days without
    water.

4
Know!
5
Freshwater is an irreplaceable resource that we
are managing poorly
  • Huge amounts of water are needed to supply us
    with food, shelter, and meet our other daily
    needs and wants.
  • Water helps to sculpt the earths surface,
    moderate climate, and remove and dilute wastes
    and pollutants.

6
  • Water is one of our most poorly managed
    resources.
  • People waste and pollute it.
  • We charge too little for making it available.

7
Most of the earths freshwater is not available
to us
  • The worlds freshwater supply is continually
    collected, purified, recycled, and distributed in
    the earths hydrologic cycle, except when
  • Overloaded with pollutants.
  • We withdraw water from underground and surface
    water supplies faster than it is replenished.
  • We alter long-term precipitation rates and
    distribution patterns of freshwater through our
    influence on projected climate change.

8
Groundwater and surface water are critical
resources
  • Ground water - precipitation that infiltrates the
    ground and percolates downward through spaces in
    soil, gravel, and rock until an impenetrable
    layer of rock stops itone of our most important
    sources of freshwater.
  • The zone of saturation is where the spaces are
    completely filled with water.
  • The top of this groundwater zone is the water
    table.

Know!
9
Water table
10
(No Transcript)
11
Groundwater and surface water are critical
resources
  • Aquifers underground caverns and porous layers
    of sand, gravel, or bedrock through which
    groundwater flowstypically moving only a meter
    or so (about 3 feet) per year and rarely more
    than 0.3 meter (1 foot) per day.

Know!
12
surface water
  • Surface water is the freshwater from
    precipitation and snowmelt that flows across the
    earths land surface and into lakes, wetlands,
    streams, rivers, estuaries, and ultimately to the
    oceans.

13
We use a large and growing portion of the worlds
reliable runoff
  • Worldwide, about 70 of the water we withdraw
    each year comes from rivers, lakes, and aquifers
    to irrigate cropland, industry uses another 20,
    and residences 10.
  • Affluent lifestyles require large amounts of
    water.

14
Freshwater shortages will grow
  • The main factors that cause water scarcity in any
    particular area are
  • a dry climate,
  • drought,
  • too many people using a water supply more quickly
    than it can be replenished, and
  • wasteful use of water.

15
The worlds major river basins differ in their
degree of freshwater-scarcity stress
More than 30 countriesmainly in the Middle East
and Africanow face water scarcity. By 2050, 60
countries, many of them in Asia, with
three-fourths of the worlds population, are
likely to be suffering from water stress.
16
Freshwater shortages will grow
  • By 2025, at least 3 billion people are likely to
    lack access to clean water.

17
HOW CAN WE INCREASE WATER SUPPLIES?
  • Section 11-2

18
Groundwater is being withdrawn faster than it is
replenished in some areas
  • Aquifers provide drinking water for nearly half
    of the worlds people.
  • Most aquifers are renewable resources unless
    their water becomes contaminated or is removed
    faster than it is replenished by rainfall.
  • Water tables are falling in many areas of the
    world because the rate of pumping water from
    aquifers (mostly to irrigate crops) exceeds the
    rate of natural recharge from rainfall and
    snowmelt.

19
Aquifers are being overpumped
  • The worlds three largest grain producersChina,
    India, and the United Statesas well as Mexico,
    Saudi Arabia, Iran, Yemen, Israel, and Pakistan
    are overpumping many of their aquifers.

20
Withdrawing groundwater has advantages and
disadvantages
21
Irrigation in Saudi Arabia between 1986 (left)
and 2004 (right)
22
Groundwater overdrafts in the United States
23
Overpumping of aquifers has several harmful
effects
  • As water tables drop, farmers must drill deeper
    wells, buy larger pumps, and use more electricity
    to run those pumps. Poor farmers cannot afford to
    do this and end up losing their land.

24
Harmful effects of Overpumping
  • Withdrawing large amounts of groundwater causes
    the sand and rock in aquifers to collapse.
  • This causes the land above the aquifer to subside
    or sink (land subsidence), referred to as a
    sinkhole.
  • Once an aquifer becomes compressed by subsidence,
    recharge is impossible.
  • In addition, land subsidence can damage roadways,
    water and sewer lines, and building foundations.

Know!
25
Overpumping of aquifers has several harmful
effects
  • Groundwater overdrafts near coastal areas can
    pull saltwater into freshwater aquifers. The
    resulting contaminated groundwater is undrinkable
    and unusable for irrigation.

26
Subsidence from overpumping
27
Solutions for groundwater depletion
28
HOW CAN WE USE FRESHWATER WATER MORE SUSTAINABLY?
  • Section 11-3

29
Reducing freshwater waste has many benefits
  • An estimated 66 of the freshwater used in the
    world is unnecessarily wasted.
  • It is economically and technically feasible to
    reduce such water losses to 15, thereby meeting
    most of the worlds water needs for the
    foreseeable future.

30
Reducing freshwater waste has many benefits
  • Reasons so much freshwater is wasted
  • Government subsidies that keep the cost of
    freshwater low.
  • Lack of government subsidies for improving the
    efficiency of freshwater use.

31
We can cut freshwater waste in irrigation
  • About 60 of the irrigation water worldwide does
    not reach the targeted crops.
  • In most irrigation systems, water is pumped from
    a groundwater or surface water source through
    unlined ditches and about 40 is lost through
    evaporation, seepage, and runoff.

32
Ways to reduce freshwater waste in irrigation
33
We can cut freshwater waste in industry and homes
  • Flushing toilets with freshwater is the largest
    use of domestic water in the US.
  • Standards have required that new toilets use no
    more than 6.1 liters (1.6 gallons) of water per
    flush.

34
We can cut freshwater waste in industry and homes
  • Fixing leaks should be a high government
    priority, would cost less than building dams or
    importing water.
  • Homeowners and businesses in water-short areas
    are using drip irrigation and replacing lawns
    with native plants that need little freshwater.

35
Florida Yard
http//floridayards.org/
36
We can cut freshwater waste in industry and homes
37
We need to use water more sustainably
38
HOW CAN WE REDUCE THE THREAT OF FLOODING?
  • Section 11-4

39
Some areas get too much water from flooding
  • To reduce the threat of flooding for people who
    live on floodplains
  • Rivers have been narrowed and straightened
    (channelized), equipped with protective levees
    and walls, and dammed to create reservoirs that
    store and release water as needed.

40
Some areas get too much water from flooding
  • Since the 1960s, human activities have
    contributed to a sharp rise in flood deaths and
    damages, meaning that such disasters are partly
    human-made.
  • Removal of water-absorbing vegetation, especially
    on hillsides, which can increase flooding and
    pollution in local streams, as well as landslides
    and mudflows.
  • Draining and building on wetlands, which
    naturally absorb floodwaters.

41
A hillside before and after deforestation
42
Fig. 11-20, p. 254
43
We can reduce flood risks
  • To improve flood control, we can rely less on
    engineering devices such as dams and levees and
    more on natures systems such as wetlands and
    natural vegetation in watersheds.

44
Ways to reduce flood risk
45
HOW CAN WE DEAL WITH WATER POLLUTION?
  • Section 11-5

46
Water pollution comes from point and nonpoint
sources
  • Water pollution is any change in water quality
    that harms humans or other living organisms or
    makes water unsuitable for human uses such as
    drinking, irrigation, and recreation.

47
Water pollution comes from point and nonpoint
sources
  • Agricultural activities are the leading cause of
    water pollution, including sediment from erosion,
    fertilizers and pesticides, bacteria from
    livestock and food-processing wastes, and excess
    salts from soils of irrigated cropland.

48
Water pollution comes from point and nonpoint
sources
  • Industrial facilities, which emit a variety of
    harmful inorganic and organic chemicals, are a
    second major source of water pollution.
  • Mining is the third biggest source of water
    pollution. Surface mining disturbs the land by
    creating major erosion of sediments and runoff of
    toxic chemicals.

49
Major Water Pollutants and Their Sources
50
The oxygen sag curve (blue) and demand curve (red)
Know!!
51
Point source
Normal clean water organisms (Trout, perch, bass,
mayfly, stonefly)
Pollution- tolerant fishes (carp, gar)
Fish absent, fungi, sludge worms, bacteria
(anaerobic)
Pollution- tolerant fishes (carp, gar)
Normal clean water organisms (Trout, perch, bass,
mayfly, stonefly)
8 ppm
Types of organisms
8 ppm
Dissolved oxygen (ppm)
Biochemical oxygen demand
Clean Zone
Recovery Zone
Septic Zone
Decomposition Zone
Clean Zone
Fig. 11-23, p. 258
52
Too little mixing and low water flow make lakes
vulnerable to water pollution
  • Lakes and reservoirs are generally less effective
    at diluting pollutants than streams.
  • Deep lakes and reservoirs often contain
    stratified layers that undergo little vertical
    mixing.
  • Little or no flow.

53
  • Lakes and reservoirs are more vulnerable than
    streams to contamination by runoff or discharge
    of plant nutrients, oil, pesticides, and
    nondegradable toxic substances such as lead,
    mercury, and arsenic.

54
Too little mixing and low water flow make lakes
vulnerable to water pollution
  • Eutrophication refers to the natural nutrient
    enrichment of a shallow lake, estuary, or
    slow-moving stream usually caused by runoff of
    plant nutrients such as nitrates and phosphates
    from surrounding land.

55
Eutrophication know this!!
56
Severe cultural eutrophication has covered this
lake in China with algae
57
Principal sources of groundwater contamination in
the U.S.
58
Polluted air
Saltwater intrusion in Florida
Hazardous waste injection well
Pesticides and fertilizers
Coal strip mine runoff
Deicing road salt
Buried gasoline and solvent tanks
Cesspool, septic tank
Pumping well
Gasoline station
Water pumping well
Waste lagoon
Sewer
Landfill
Leakage from faulty casing
Accidental spills
Discharge
Freshwater aquifer
Freshwater aquifer
Freshwater aquifer
Groundwater flow
Fig. 11-26, p. 261
59
  • Be able to list 2 sources of groundwater
    contamination.

60
Ways to prevent and clean up contamination of
groundwater
61
Residential areas, factories, and farms all
contribute to the pollution of coastal waters
62
Industry Nitrogen oxides from autos and
smokestacks, toxic chemicals, and heavy metals in
effluents flow into bays and estuaries.
Cities Toxic metals and oil from streets and
parking lots pollute waters sewage adds nitrogen
and phosphorus.
Urban sprawl Bacteria and viruses from sewers
and septic tanks contaminate shellfish beds and
close beaches runoff of fertilizer from lawns
adds nitrogen and phosphorus.
Construction sites Sediments are washed into
waterways, choking fish and plants, clouding
waters, and blocking sunlight.
Farms Runoff of pesticides, manure, and
fertilizers adds toxins and excess nitrogen and
phosphorus.
Red tides Excess nitrogen causes explosive
growth of toxic microscopic algae, poisoning
fish and marine mammals.
Closed shellfish beds
Closed beach
Oxygen-depleted zone
Toxic sediments Chemicals and toxic metals
contaminate shellfish beds, kill spawning fish,
and accumulate in the tissues of bottom feeders.
Oxygen-depleted zone Sedimentation and algae
overgrowth reduce sunlight, kill beneficial sea
grasses, use up oxygen, cause fish kills, and
degrade habitat.
Healthy zone Clear, oxygen-rich waters promote
growth of plankton and sea grasses, and support
fish.
Know!!
Fig. 11-29, p. 264
63
Reducing ocean water pollution
  • The key to protecting the oceans is to reduce the
    flow of pollution from land and air and from
    streams emptying into these waters.

64
Reducing surface water pollution from nonpoint
sources
  • Ways to reduce nonpoint-source water pollution,
    most of which comes from agriculture.
  • Reduce soil erosion by keeping cropland covered
    with vegetation.
  • Reduce the amount of fertilizer that runs off
    into surface waters.
  • Organic farming can also help prevent water
    pollution caused by nutrient overload.
  • Control runoff and infiltration of manure from
    animal feedlots.

65
Ways to help reduce or prevent water pollution
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