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Environmental Science: Toward a Sustainable Future Richard T' Wright

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Title: Environmental Science: Toward a Sustainable Future Richard T' Wright


1
Environmental Science Toward a Sustainable
Future Richard T. Wright
Chapter 7
  • Water Hydrologic Cycle and Human Use
  • PPT by Clark E. Adams

2
Water Hydrologic Cycle and Human Use
  • Water a vital resource
  • Hydrologic cycle natural cycle, human impacts
  • Water a resource to manage, a threat to control
  • Water stewardship public-policy challenges

3
Water A Vital Resource
4
Hydrologic Cycle Natural Cycle, Human Impacts
  • Evaporation, condensation, purification
  • Precipitation
  • Groundwater
  • Pools and fluxes in the cycle
  • Human impacts on the hydrologic cycle

5
Polarity in H2O The Water Molecule
covalent bond
6
Condensation
7
Temperature Determines Whether Water Is a
  • Gas steam
  • Liquid running water
  • Solid ice
  • Why does ice float?

8
The Water Cycle
9
Water Cycle Review
B
A
D
C
E
F
H
G
10
Condensation
11
Precipitation
  • Adiabatic cooling warm air rises, expands and
    cools
  • 100 relative humidity cooling clouds
  • Increasing condensation water droplets

12
Global Precipitation
  • Global precipitation distribution depends on
    patterns of rising and falling air currents
  • Two main factors
  • global convection currents
  • rain shadow effect

13
Global Air Circulation
14
Rain Shadow Effect
15
Water Balance in the Hydrologic Cycle
16
Pools and Fluxes in the Cycle
17
Human Impacts on the Water Cycle
  • Changing the Earths surface
  • Floods
  • Climate change
  • Atmospheric pollution
  • Withdrawing water supplies

18
Groundwater
  • Decreased infiltration
  • Increased runoff
  • Decreased groundwater recharge

19
Human Impacts on the Hydrologic Cycle
20
Water A Resource to Manage, A Threat to Control
  • Uses and sources
  • Surface waters

21
Water Uses
22
Water Uses
23
Municipal Water Use and Treatment
What is your communitys water source?
24
Surface Waters
  • Dam impacts (see Fig. 7-15)
  • Ecological effects of changing salinity in
    estuaries
  • Increased salinity
  • Loss of native species
  • Invasive species increase

25
Consequences of Overdrawing Groundwater
  • Falling water tables
  • Diminishing surface waters (wetlands)
  • Land subsidence (see Fig. 7-17)
  • Saltwater intrusion

26
Aquifer Exploitation
  • Groundwater use exceeds aquifer recharge
  • Many remaining aquifers are heavily polluted

27
Saltwater Intrusion
28
Water Stewardship Public-Policy Challenges
  • Obtaining more water
  • Groundwater
  • Using less water
  • Public-policy challenges

29
Dams
  • Three Gorges Dam
  • Largest in world
  • Controls deadly floods
  • Displaced 1.2 million people including farms,
    cities, homes, and factories
  • 370-mile-long reservoir

30
Dams Disrupt Integrity of River System
  • Above the dam
  • Flooding
  • Sediment deposition
  • Loss of functional floodplain
  • Below the dam
  • Loss of normal river flow patterns
  • Loss of river biota
  • Loss of functional floodplain

31
Using Less Water
  • Irrigation
  • Surge flow
  • Drip irrigation
  • Municipal uses
  • Incentives and regulations limiting water use
  • Gray water

32
Desalting Seawater
  • Reverse osmosis
  • Distillation

33
Public-Policy Challenges
34
National Water Policy
  • Promote water efficiency
  • Reduce or eliminate water subsidies
  • Charge polluters
  • Add watershed management to pricing of water

35
National Water Policy
  • United States must respond to global water crisis
  • United States must reduce emission of greenhouse
    gases
  • Need more data for informed policy decisions

36
End of Chapter 7
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