Cities can be traced back to the river valley civilizations of Mesopotamia, Egypt, Indus Valley and China. These settlements were largely dependent upon agriculture surplus in initial days. With the growth of population the city size increased and the economic activity transformed to trading and other secondary activities. The process of urbanization accelerated with industrial revolution 200 years ago and further with globalization in 1990’s.
Urbanisation refers to the growth of the towns and cities due to large proportion of the population living in urban areas and its suburbs at the expense of its rural areas. In most of the countries the total population living in the urban regions has increased since the Second World War. Current global population is 7,057,075,000 billion (Population Reference Bureau, 2005; United Nations, 2011).
The rapid urbanization of the world’s population over the 20th century is evident from the dramatic increase in global urban population from 13% (220 million, in 1900), to 29% (732 million, in 1950), to 49% (3.2 billion, in 2005) and is expected to increase to 60% (4.9 billion) by 2030 and 9.6 billion in 2050 (United Nations, 2011).Urban population has been increasing three times faster than the rural population, mainly due to migration in most parts of the world (Girardet 1996; Massey et. al., 1999).
People migrate to urban areas with the hope of a better living, considering relatively better infrastructural facilities (education, recreation, health centers, banking, transport and communication), and higher per capita income. However, rapid unplanned urbanization has led to serious problems in urban areas due to higher pollution (air, water, noise) inequitable distribution of natural traffic congestion, development of shanty towns and slums, unemployment, increased reliance on fossil fuels, and uncontrolled outgrowth or sprawl in the periphery The direct implication of such urbanisation is the change in land use and land cover of the region.
Urban ecosystems are the consequence of the intrinsic nature of humans as social beings to live together (Sudhira, et al., 2003). The process of urbanisation contributed by infrastructure initiatives and consequent population growth and migration results in the growth of villages into towns, towns into cities and cities into metros. However, in such a phenomenon for ecologically feasible development, planning requires an understanding of the growth dynamics. Nevertheless, in most cases there are lot of inadequacies to ascertain the nature of uncontrolled progression of urban sprawls.
Urban sprawl refers to the dispersed development along highways or surrounding the city and in rural countryside with implications such as loss of agricultural land, open space and ecologically sensitive habitats. Sprawl is thus a pattern and pace of land use in which the rate of land consumed for urban purposes exceeds the rate of population growth resulting in an inefficient and consumptive use of land and its associated resources. This phenomenon is characterized by an unplanned and uneven pattern of growth, driven by multitude of processes evident from lack of basic amenities. Urban sprawl is thus a term often used variously to mean the gluttonous use of land, uninterrupted monotonous development, leapfrog discontinuous development and inefficient use of land that are influenced by a myriad of factors, including land features, infrastructure, policies, and individual characteristics. This is characterised by low levels of some combination of eight distinct dimensions such as density, continuity, concentration, clustering, centrality, nuclearity, mixed uses and proximity.
Process of urbanisation bring the development of a region , which could be planned (in the form of townships) or unplanned (organic). Unplanned urbanization leads to the haphazard or irregular growth with the loss of green spaces and water bodies. Dispersed urban growth without proper infrastructure and basic amenities is often referred as sprawl and this phenomenon is widespread in developing countries. Implications of sprawl are excess demand on natural resources, improper allocation of basic amenities and infrastructure, , deteriorating water quality, an increased potential for harboring disease vectors, etc. Large scale land use and land cover changes, such as the loss of forests to meet the urban demands of fuel and has led to the changes in the ecosystem structure, impacting its functioning and thereby threatening sustainable development.