It may appear that urban centres have experienced a simplistic growth from being the smallest to the largest through an inherent unidirectional process. But scholars over time have come up with different theories to track the growth of the urban nodes through sequential stages.
Theoretically, several models have tried to explain the stages of urban growth (Das and Bhusan, 2014). The classic structural change model of Chenery and Syrquin (1979) identified characteristic features of the development process, such as the shift from agricultural (primary) to industrial (secondary) production and Northam (1979) identified characteristic phases of urbanization on the basis of logistic patterns in urban growth.
On the other hand, some models have even tried to phase out urban growth on the basis of GDP per capita, industrial structure (the proportion of the economy devoted to primary, secondary, or tertiary industry), employment structure (the proportion of jobs associated with each industrial sector) and level of urbanization (the proportion of the non-farm population in cities) as indicators of the stage of city development (Wang, Liu, Peng, Chen, Driskell, Zheng, 2011).
However, Berg, Drewett, Klassen, Rossi and Vijverberg 1982 conceptualised urban growth in well-sequenced stages and generated a model of urban growth on the basis of population growth in the urban regions and the shifts in population between the core and the peripheral zones. The population mostly focuses on the core of their economic activities. Berg’s model proposed that the urban regions develop in well-deciphered stages of Urbanisation, Suburbanisation/Ex-urbanisation, Counter-urbanisation and Re- urbanisation (Clarke, 2003).
Theories of interdependency, mercantilism and of global urban development have sought to propose a kind of causal between processes of wealth accumulation and the creation of a hierarchy of urban spaces. These have further talked of urban development as consequent upon the stages of economic development from mercantilism through industrial and monopoly capitalism to corporate capitalism. In the later stages of economic development, the urban spaces at the macro level are open to the exchange of both human and social capital.
However, if the same is thought of at a much smaller scale i.e. at a meso level, then such hierarchies are also found to exist within urban regions of a particular nation. In India for example, the urban population is found to be concentrated in a few of the major states and further if such individual states are considered then a primacy is indicated in some of the major cities or urban agglomerations in them (e.g., Kolkata UA accounts more than 48.4 per cent of the total urban population of West Bengal in 2011).
Klassen et.al (1981) and van den Breg (1982) have employed the concept of cyclic urbanization within individual urban agglomerations and have identified four major stages in which they grow. The stages may be summed up as:
a. Urbanisation
b. Suburbanization or Exurbanisation
c. Disurbanisation or Counterurbanisation and
d. Reurbanisation
While in the stage of urbanization, certain settlement grows and expand at the cost of their surrounding countryside, the suburbanization or the exurbanisation phase experiences the growth of the peripheral ones of urban settlements at a higher rate in comparison to the core.
In the stage of counter-urbanization, the core experiences a loss of urban population which far exceeds the rate of population gain at the peripheries resulting in the overall loss of the urban settlement in terms of population numbers and in the stage of reurbanisation, the core starts gaining population whereas the ring keeps on loosing population.
However, Breg’s model is based on the changes in the rate and direction of population movement between the urban core and the peripheral ring which together form the daily urban system (DUS) which together are functionally interrelated. Absolute change is noted in the urban settlement in cases the core and the ring experience change in population in two different directions and relative change is experienced when the population moves in both zones but at different rates but in the same direction.
The stages with their relative change in the direction of the population have been summed up in the following figure:
Figure: Stages of Urban Development after van den Breg
Geyer and Kontuly (1993) postulated the phases of urban growth in their theory of Generalised Stages of Differential Urbanisation. They identified that the cities grow through the following stages:
a. The primate city phase
b. The intermediate city phase and
c. The small city phase
In the initial primate city phase, population growth and economic activities are concentrated in the rapidly growing primate cities. The cities slowly attain their multi-nodal character through the stages of early primate city, intermediate primate city phase and advanced primate city phase.
On the other hand, the intermediate city phase is characterized by the slowing down of the growth rate of the primate city and spatial deconcentration. This phase experiences the growth of intermediate-sized cities in close proximity to the primate city.
The small city phase on the other hand sees the growth of small urban centres which grow at a much faster rate in comparison to the primate city and the intermediate cities.
It, therefore, follows that cities are constantly changing in terms of their population numbers and in comparison to the proportion staying in their rural counterparts. This change in the cities’ morphology and size is mainly in response to the ongoing changes in the social, economic and demographic scenario and different scholars have tried to phase the cities’ growth in different characteristics stages.
However, it would be interesting to note that the cities mainly add the population through two main processes natural increase (with a higher birth rate than death rate) and through migration. It may be noted that the sequential phases of urban growth have been mainly proposed from the western experience of urbanization and therefore may not be true for developing countries.
However, if the stages of growth for the Indian cities are taken into account, the phenomenon may not be explained by a single model or theory but rather a combination of a set of these.