The rate of population growth is very high in case of developing countries rather than the developed countries
The rate of population growth is very high in case of developing countries rather than the developed countries. In 1950, 30 percent of the world population was urban area but in 2050, 66 percent of the population is projected to be urban area (United Nations, 2014). In the last decade, most of the cities in the world have experienced high growth rate of population among them most of the cities are from the developing countries which is characterized by the rapid transformation of land use/land cover (i.e. from rural or semi urban areas to urban areas). (Yu & Qingyun, 2011). This rural to urban transformation is mainly because of increase in population and huge economic and infrastructural development which leads to change in socio economic environment of the city (Bounoua, 2009). Recently urban area occupies only 3 percent of the Earth’s total land surface, but it have marked effects on environmental conditions at both local, regional and also in global scales (Herold, et al., 2003; Liu and Lathorp, 2002).
The transformation of rural or semi urban areas to urban areas through the process of urbanization is now a day’s occurring at an unprecedented rate which affected on the natural functioning ecosystems of the city (Turner, 1994). Transformation of the agricultural areas to the urban areas may create different problems like land degradation and desertification (Shalaby et al., 2004). This is the causes behind the city externalities.
1.2. Urbanization, Urban Growth and City Externalities
Urbanization is an important characteristic in case of every metropolitan region around the world. Urbanization can be defined as the conversion of rural or semi urban areas to urban areas (Antrop, 2000) (Burgi, et al., 2004) (Pickett, et al., 2001). Rapid urbanization especially in the metropolitan cities of the developed countries often causes enormous pressure on physical and socio-economic environments of the area.
Urbanization is also one of the dynamic processes which are mainly induced by the human activities but it is also responsible for the loss of agricultural land (Lopez et al. 2001). It leads to urban growth. But the spatial pattern of urban growth is a consequence of the interaction between the various physical and socio-economic factors (Burgi et al. 2004). Different factors like topography, population, land use land cover types, infrastructural development of an urban area impacted on the morphology, which leads into different types of urban growth. Urban growth is mainly the conversion of semi urban or rural area to commercial area. It is also related with the regional economic sustainability of an area. Its benefits are increasingly balanced against the environmental and ecological impacts, which are also affected on the air quality and water quality with the loss of agricultural tracts of an area. It also affected the socio economic condition of an area which leads into regional disparities, social fragmentation etc. (Squires, 2002).