Density, Urban Sprawl and Use of Land(6)
A recent study commissioned by the World Bank shows that modern patterns of city growth are increasingly land-intensive.(7)Average urban densities (that is, the number of inhabitants per square kilometre of built-up area) have been declining for the past two centuries. As transportation continues to improve, the tendency is for cities to use up more and more land per person.(8)
The built-up area of cities with populations of 100,000 or more presently occupy a total of about 400,000 km2, half of it in the developing world. Cities in developing countries have many more people but occupy less space per inhabitant. In both developing and industrialized countries, the average density of cities has been declining quickly: at an annual rate of 1.7 per cent over the last decade in developing countries and 2.2 per cent in industrialized countries.(9)
Modern patterns of city growth are
increasingly land-intensive. Average urban
densities...have been declining for the past
two centuries. As transportation continues
to improve, the tendency is for cities to use
up more and more land per person.
In developing countries, cities of 100,000 or more are expected to triple their built-up land area to 600,000 km2 in the first three decades of this century. Cities in developed countries expand at an even faster rate per resident, despite their smaller population size and lower rate of population growth. They will increase their built-up land area by 2.5 times between 2000 and 2030. At that point, they will occupy some 500,000 km2.(10)
Thus, should recent trends persist over the next 30 years, the built-up land area (i.e., excluding green areas) of cities of 100,000 or more would grow from a territory the size of Sweden to one like Ethiopia. But these projections might actually understate the possibilities. Recent trends to lower densities may accelerate as globalization has its effect on lifestyles and production processes. Whatever the case, the data show that developing countries now share the trend to urban sprawl.
Urban sprawl results from the combination of different types of pressures on territorial expansion. For purposes of simplicity, these can be classified into two groups: residential suburbanization and peri-urbanization.