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)
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Population (Millions)
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10
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% Urban
% Rural
Texas Pop.
1900
1910
1920
1930
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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