cunningham - cunningham - saigo: environmental science 7 th ed. urbanization and sustainable cities...

Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

Urbanization and Sustainable Cities

Chapter 24


Outline:

• Urbanization• Causes of Urban Growth

Push and Pull Factors• Current Urban Problems

Developing World Developed World

- Urban Sprawl- Open Space

• Sustainable Development of the Third World


URBANIZATION

• Vast majority of humanity has always lived in rural areas where natural resource-based occupations provided support. Since beginning of Industrial Revolution

cites have grown rapidly in size and power.- Urbanization - Increasing concentration

of population in cites and transformation of land use and society to metropolitan patterns of organization.

Nearly half world population now lives in urban areas.


What Is A City ?

• US Census Bureau considers any incorporated community a city, and any city with more than 2,500 residents as urban. In rural areas, most residents depend on

natural resources for their livelihood. In urban areas, most people are not

directly dependent on natural resource-based occupations.


What Is A City ?

• A village is a collection of rural households linked by culture, customs, family ties, and association with the land. A city has a large enough resource base to

allow residents to specialize in arts, crafts, services, or professions other than resource-based occupations.

- A megacity is an urban area with more than 10 million inhabitants.


World Urbanization

• In 1850, only 2% of world population lived in cities. By 2000, 47% of world population lived in

urban areas.- Only Africa and South Asia remain

predominantly rural. Expected that 90% of population growth

over the next 25 years will occur in less-developed countries.


Urban and Rural Growth


World Urbanization

• Urban growth has been particularly dramatic in the largest cities, especially in the developing world. A century ago, London was the only city

with more than 5 million people.- Nineteen cites currently have

populations larger than 5 million.


World Urbanization

• Some futurists predict 93 cities with a population of at least 5 million by 2025. Three-fourths in developing world.

- In developing world megacities, as much as half of urban population are transient workers or residents of shanty towns.

By some estimates, Mexico City has a current population of 25 million, and grows by 750,000 each year.


World Urbanization


CAUSES OF URBAN GROWTH

• Two main avenues of urban growth: Natural Increase

- Fueled by improved food supplies and medical care.

Immigration- Caused by push factors forcing people

out of the country, and pull factors drawing them into cities.


Immigration Push Factors

• Overpopulation• Economics• Politics• Racial or Religious Conflicts• Land Tenure• Changes in Agriculture

Large Monoculture Farms


Immigration Pull Factors

• Excitement and Vitality• Jobs• Housing• Entertainment• Social Mobility and Power• Specialization of Professions


Government Policies

• Government policies often favor urban over rural areas in push and pull factors. Developing countries often spend majority

of budgets on improving urban areas.- Major cities gain a monopoly on new

jobs, education and general opportunities.


CURRENT URBAN PROBLEMS

• Developing World Uncontrollable Growth

- Traffic and Congestion- Air Pollution- Sewer Systems and Water Pollution

Only 35% of urban residents in developing world have satisfactory sanitation.

About same percentage do not have safe drinking water.


Current World Problems

- Housing At least 1 million people live in slums

of central cities and in shantytowns in the outskirts of cities.



• Developed World Rapid growth of cities that accompanied

industrialization has mostly slowed or reversed.

- Many of the environmental problems have been reduced.

Many of major polluters have moved to developing countries.



• Developed World Urban Sprawl

- In most American metropolitan areas, the bulk of new housing is in large, tract developments that leapfrog beyond city edges in search of inexpensive land.

Consumes about 200,000 ha of US agricultural land annually.

Planning authority is often divided among many small local jurisdictions.


Urban Sprawl

• Because many Americans live far from work, they consider a private automobile essential. Average US driver spends 443 hours per

year behind a steering wheel.- In some metropolitan areas, it is

estimated one-third of all land is devoted to automobile infrastructure.

Traffic congestion costs US $78 billion annually in wasted fuel and time.


Urban Sprawl

• With a reduced tax base and fewer civic leaders living or working in downtown areas, the city is unable to maintain its infrastructure. Low density development of suburbs is

racially and economically exclusionary because it provides no affordable housing and makes a viable public transit system impractical.


Smart Growth

• Smart Growth makes efficient and effective use of land resources and existing infrastructure by encouraging in-fill development. Also attempts to provide a variety of

transportation options.- Goal is staged, managed growth that

protects environmental quality and diversity.


Garden Cities and New Towns

• New Towns - Numerous experiments to try and combine best features of rural village and modern city. Ebenezer Howard (1898) proposed

congestion of London could be relieved by moving whole neighborhoods to garden cities separated from the central city by a greenbelt of forest and fields.


New Urbanist Movement

• Limit city size, or organize into modules of 30,000 to 50,000 people.

• Determine in advance where development will take place.

• Turn shopping malls into city centers.• Locate everyday services more conveniently.• Increase jobs in a community by locating

offices and commercial centers near suburbs.• Encourage walking and low-speed vehicles.


New Urbanist Movement

• Promote diversity in housing designs.• Create housing “superblocks.”• Make cities more self-sustainable.• Incorporate rooftop gardens or vegetation.• Invite public participation in decision-making.


Designing For Open Space

• Traditional suburban development typically divides land into a checkerboard layout of nearly identical 1-5 ha parcels with no designated open space. Conservation Development - Preserves at

least half of a subdivision as natural areas, farmland, or other forms of open space.


Designing For Open Space


SUSTAINABLE DEVELOPMENT IN THE THIRD WORLD

• Many planners argue social justice and sustainable economic development are answers to urban problems. Another important measure of progress

may be institution of social welfare providing care to the sick and elderly.

• Others argue the best hope for developing countries may be to “delink” from established international economic systems and develop self-sustainability.


Summary:

• Urbanization• Causes of Urban Growth

Push and Pull Factors• Current Urban Problems

Developing World Developed World

- Urban Sprawl- Open Space

• Sustainable Development of the Third World

cunningham - cunningham - saigo: environmental science 7 th ed. urbanization and sustainable cities...

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