Environmental Sciences: Toward a Sustainable Future Chapter 24

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Transcript Environmental Sciences: Toward a Sustainable Future Chapter 24

Sustainable Communities
and Lifestyles
The Impacts of U.S. “Urban Sprawl”
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What is it? “The Suburbs”
When did it begin and why?
How is the environment changed?
What are the consequences of “exurban
migration”?
• Why Clustered Living and Development”?
Urban Sprawl
• Expansion of metropolitan areas (suburbs).
• More houses, shopping centers and highways
farther from city centers.
• Lack of overall land-use planning.
• Facilitates extravagant consumption of resources.
– Energy
– Materials
• Loss of “green-space” and farmland
• Increased pollution (smog)
Factors That Contributed To
Urban Sprawl - post-WWII
City overcrowding & pollution
Farmland sale and conversion
Cheap accessible mortgages
Easy car ownership
Post-war savings
Highway Trust Fund (1956)
20
15
10
5
0
Population (Millions)
90
80
70
60
50
40
30
20
10
0
% Urban
% Rural
Texas Pop.
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
Percent Urban or Rural
Rate of Urbanization in Texas
Decades
Country Mouse to City Mouse
Environmental Impacts of
Urban Sprawl
• Development on forests and grasslands =
– Reduced water quality
– Reduced air quality
– Fewer renewable resources
– Wildlife loss (biodiversity loss)
• Hydrologic Cycle Modification
– Increased runoff, erosion, flooding
– Reduced water quality and water table level
• Ecosystem simplification and destabilization
Wildlife Loss Mechanisms
of Highways and Development
• Direct habitat
destruction
• Habitat fragmentation
– Territories too small
– Migration interrupted
• Access to water
prevented
• Highway fatalities
(them not us)
Urban Wildlife
Management Problems
• Changed societal
attitudes towards
animals
• Urban cougar,
deer, and geese
populations
Environmental Impacts of
Urban Sprawl
(Figure 24-6)
Indicators of Urban Blight/Decay
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Economic and ethnic segregation
Eroding tax base
Loss of social services
Lowered property values
Higher property tax rates
(improvements will result in more taxes)
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Deterioration of central city infrastructure
Decline in education quality
Loss of jobs and self esteem
More drug trafficking and violent crime
Consequence of Exurban Migration
= Urban Blight/Decay!
What Makes Cities Livable?
Why Clustered Living?
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Minimal commuting distance
Reduced automobile traffic
Improved access by foot or bicycle
Improve mass transit
Efficient central heating opportunities
Heterogeneity of residences and
businesses (cultural diversity)
• People meet people not cars
City Rehabilitation and
Clustered Development
• Integrated living, working and recreational spaces
(close proximity of shops, residences, services …)
• Affordable housing (smaller; town-homes)
• Use alternative energy sources (e.g. solar).
• Provisions for pedestrian and bicycle traffic.
• Self-sufficiency in provision of food
• Protection of sensitive habitats
• Stable population