We are all familiar with the pattern. Last year's cornfield and barn or wooded area and stream are replaced by this year's subdivision, strip mall, or gas station and fast- food restaurant. And the next year the story is repeated over again. The edge of town seems to keep moving farther and farther into what once was the country. Soon the roads are widened or maybe a whole new highway is built to accommodate the increased traffic from the new houses, malls, gas stations, and restaurants. As the refrain from a once-popular song goes, it looks like "they paved paradise and put up a parking lot."
This all-too-familiar scenario is descriptive of urban sprawl. Exactly what is urban sprawl? ENVIRONMENTAL SCIENCE: TOWARD A SUSTAINABLE FUTURE offers this illustration (page 599) and definition (page 667) of the problem:
urban sprawl. The rapid expansion of metropolitan areas through building housing developments and shopping centers farther and farther from urban centers and lacing them together with more and more major highways. Widespread development that has occurred without any overall land-use plan.
Urban sprawl is not restricted to the Midwest, but is occurring across the country. However, several Midwestern cities have been identified by the Sierra Club as among the most sprawl-threatened cities in the country. These cities include: St. Louis, Cincinnati, Kansas City, Minneapolis - St. Paul, Chicago, Akron, and Little Rock.
Urban sprawl is a post-World War II phenomenon. The causes of the development of sprawl are complex, but several key factors are generally cited as contributing. Home- buying subsidies provided by the GI Bill allowed many couples to secure their part of the American Dream, their own home. The post-war baby boom contributed to a demand for additional housing. Rapid, large-scale housing construction took place at the margins of existing urban centers, giving rise to growth of the suburbs. At the same time, the automobile was gaining in popularity and affordability. Also, gasoline taxes were made available to subsidize massive road construction projects, including the interstate highway system.
As the suburbs developed and roads and highways sprouted, business and industries followed the population migration from urban to suburban areas. As further growth occurred, newer suburbs expanding into previously rural areas encircled older suburbs. This outward expansion of urban growth continues to the present around most metropolitan areas.
Several decades of unchecked urban sprawl have resulted in a host of environmental, economic, and social problems.
1. Loss of Agricultural Lands
The continued growth of suburban areas has often come at the expense of loss of productive agricultural lands. It is estimated that between 1982 and 1992 more than four million acres of farmlands were lost to urban development. Presently, there are large areas of high-quality farmland in the path of development throughout the country. The long-term impacts of this trend are troubling. American farmers will be called upon to produce ever-increasing quantities of food due to the demands of population growth from ever-decreasing amounts of land due to the loss of acreage to urban development.
2. Loss of Forests, Wetlands, and Wildlife Habitat
Just as farmland acreage is lost to urban sprawl, so too are natural areas of woodlands and wetlands which are important wildlife habitats. The threats of urban sprawl to wildlife are particularly acute for those species that are already threatened or endangered.
3. Alterations in Hydrology
The process of urban development alters the hydrology of an area in multiple ways. The actions of bulldozers and graders to prepare the land for development will often change the existing drainage patterns of land. Pavement, culverts, and sewers will further alter the drainage pattern. Paving over of the land by concrete and asphalt will reduce infiltration of water into the soil. This reduced infiltration will interfere with aquifer recharge. Also, the rapid run-off of precipitation from paved surfaces will enhance the probability of flooding from heavy rains.
4. Increased Air and Water Pollution
The increased automobile use necessitated by urban sprawl generates increased air pollution from vehicular traffic. Sprawl also contributes to water pollution as run-off from paved areas carries pollutants from cars, homes, and businesses and industries into waterways. Erosion from lands cleared for development can carry excess sediments into streams, smothering aquatic habitats.
5. Increased Petroleum Use and CO2 Release
Sprawl requires an increase in vehicle miles traveled per person. While population of the United States increased by 23% from 1969 to 1989, vehicle miles traveled per person increased by 98%. These longer drives put greater demands on depleting reserves of petroleum, negatively influence America's balance of trade by requiring more oil imports, and result in larger release of CO2, contributing to global climate change.
6. Increased Infrastructure Costs
Accompanying urban development is the construction of new roads, curbs, sidewalks, sewers, wastewater treatment plants, and utility (electric, gas, water, and telephone) lines. With increasing sprawl, the distances traversed by these infrastructure additions become increasingly expensive, particularly when computed on a per person/household basis.
7. Degradation of Inner Cities
As people migrate from cities to suburban areas, businesses and industries follow. This erodes the tax base of cities and citizen commitment to maintenance of inner city areas. Older buildings, abandoned as people and commerce flee to suburbs, fall into disrepair. Neighborhoods, business districts, and historic sites of the inner city decay and fall into ruin.
8. Loss of a Sense of Place
With powerful and provocative rhetoric, James Howard Kunstler has described the landscape created by urban sprawl as "the geography of nowhere" and as "a cartoon of a human habitat." In the past, there was a distinctiveness to geographic regions of the country, individual cities, and areas within a single city. This uniqueness has given way to the homogenization and sameness created by urban sprawl. Kunstler argues that urban sprawl is both a symptom and a cause of a troubled culture.
Numerous "smart-growth" strategies have been developed for confronting the issue of urban sprawl.1. Urban Growth Boundaries
2. Infill Development
Infill development takes advantage of underutilized areas within existing urban areas for the construction of new homes, businesses, and industries. Rather than development of rural areas ever farther from the heart of cities, infill housing promotes redesign and growth within existing urban boundaries.
3. Transfer of Development Rights
Transfer of Development Rights is a tool by which communities can regulate the density of development of designated geographic areas. Certain areas are allowed higher-density development in exchange for lower- density development in other areas.
4. Open- Space Zoning
Open-Space Zoning is an alternative to conventional housing development in which the land is evenly divided into relatively large parcels with little open space between the parcels. Under open-space zoning, houses are restricted to a relatively small portion of the land under development and the remainder of the area is reserved for open spaces, natural areas, and farmlands.
5. Conservation Easements
Conservation Easements are a legal mechanism for the long-term protection of natural areas and farmlands from the threat of urban development.
The textbook provides an extensive background on urban sprawl.
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