An urban area is defined as a town or city plus its adjacent suburban fringes with a population of between10,000-50,000. A rural area usually is defined as an area with a population of less than 2,500 people.
Urbanization is the process in which people increasingly move from rural areas to densely populated cities; also involves the transformation of rural areas into urban areas. A country’s degree of urbanization is the percentage of its population living in an urban area.
Urban growth is the rate of increase of urban populations. Urban areas grow in two ways: by natural increase (more births than deaths) and by immigration (mostly from rural areas).
Migration is influenced by ‘push factor’ and ‘pull factor’. People can be pushed from rural areas into urban areas by factors such as poverty, lack of land to grow food, declining agricultural jobs, famine, and war.
Rural people are pulled to urban areas in search of jobs, food, housing, health care, a better life, entertainment, and freedom from religious, racial, and political conflicts. Developing countries-fueled by government politics distribute most income and social services to urban dwellers.
Trends Important in Understanding the problems and Challenges of Urban Growth
Several trends are important in understanding the problems and challenges of urban growth.
First, the proportion of the global population living in urban areas increased from 2% to 47%. According to UN projections, by 2050 about 63% of the world’s people will be living in urban areas, with 90% of this urban growth occurring in developing countries.
Second, the number of large cities is mushrooming. In 1900, only 19 cities had a million or more people, and more than 95% of humanity lived in rural communities. In 2003, more than 400 cities had a million or more people (projected to increase to 564 by 2015). The world’s fiver largest cities are 1) Tokyo, Japan, 2) Mexico city, Mexico, 3) Bombay, India, 4) Sao Paulo, Brazil, and 5) New York in the United States. As they grow outward, separate urban areas may merge to form a megalopolis.
A third trend is that urbanization and the urban population is increasing rapidly in developing countries. Currently, about 40% of the people in developing countries live in urban areas. Developing countries contain 1.8 billion urban dwellers and are projected to reach at least 57% urbanization by 2025. Most of this growth will occur in large cities, which already have trouble supplying their residents with water, food, housing, jobs, sanitation, and basic services.
Fourth, urban growth is much slower in developed countries (with 75% urbanization) than in developing countries. Still, developed countries are projected to reach 84% urbanization by 2025.
Finally, poverty is becoming increasingly urbanized as more poor people migrate from rural to urban areas. The UN estimates that at least 1 billion people live in crowded slums of central cities and in squatter settlements and shantytowns that surrounds the outskirts of most cities in developing countries.
Major Environmental Pros and Cons of Urban Areas
• In terms of resource use, most of the world’s cities are not self-sustaining systems because of their high resource input and high waste output. They survive only by importing food, water, energy, minerals, and other resources from farms, forests, mines, and watersheds. ▪ They also produce enormous quantities of wastes that can pollute air, water, and land within and outside their boundaries. . Because of their high population densities and high resource consumption, urban dwellers produce most of the world’s air pollution, water pollution, solid and hazardous wastes. Some of this comes from motor vehicles, which have contributed lead in gasoline, nitrogen oxides, ozone, carbon monoxide, and other air pollutants from exhaust. Stationary power sources also produce air...