In any study of population distribution, it is necessary identify factors which determine the way in which it is distribution within an area of a country, or in a country as well as in continent in which that country lies, or in a region, or in the world considered as a whole.
These factors provide the necessary explanation for particular patterns of population distribution are generally grouped into three categories: (1) Geographical factor (2) Economic and social factors; and (3) Demographic factors. The categories, however, are in no way like water-tight compartment.
There is a great deal of interaction among the three types of facto which makes it difficult for us to identify one type of factor being exclusively responsible for a particular pattern of population distribution.
Geographic Factors of Population Distribution
Physical conditions, such as climate (temperature and rainfall), landforms in terms of altitudes, the quality of the soil and the availability of energy and mine resources are the important geographical determinants of population distribution. Another important factor is the relationship between the location of one place and other places of importance.
Climate is one of the most important natural conditions which have historically played a vital role in the development of hum life, for it is the main factor determining the formation of botany environment and of vegetable and animal associations.
Geography therefore, usually considers the main climatic belts of the earth as the framework within which human activity takes place.
With technological progress and increasing control over nature, man has been able to affect many of the influences of climatic conditions. The importance of the role of climatic conditions with respect to population distribution is, therefore, inversely related to the stage of technological advancement reached by any country.
Temperature is an important factor to be considered in climate conditions. It is obvious that wherever there are extremes of temperature, human life is difficult to sustain, and consequently such areas are sparsely inhabited.
The most appropriate example of temperature affecting population distribution is the one provided by the Arctic and Subtract Regions where, because of long and very cold winter nights and low intensity of solar radiation even during the summer, living conditions are extremely difficult and the energy of human beings is spent mainly on struggling against the difficult conditions created by nature.
It has been estimated that 6.4 million square miles of the earth are too cold for cropping.When temperatures are very high and are combined with humidity, such conditions may not be too attractive for those who may wish to migrate to these places for other reasons, thus affecting population growth due to immigration.
As water is essential for human survival, population distribution is largely determined by rainfall and other sources of water supply like rivers, wells, etc.
The extreme case is that of large expanses of deserts, where there is no population at all because of the absence of any source of water supply. On the other hand, several ancient civilisations flourished on the banks of rivers.
In this context, the role of the Nile in Egypt and the Ganges in India is worth noting. Writing about the distribution of population in pre-partition India on the basis of the 1941 census, Kingsley Davis observes: "In other words, the region's population is heavily concentrated in the well-watered river and coastal plains."
The nature of the terrain is also an important geographic feature determining population distribution. Wherever the terrain is difficult, the area is sparsely populated.
For instance, in a mountainous region, population density is low because the area of arable land is limited, and it is difficult to maintain even the existing arable land.
In addition, the cost of transportation and of constructing, maintaining and operating agricultural equipment, is high; and the high altitude also adversely affects human activity.
It has been estimated that high mountains, which generally tend to discourage human settlements, occupy more than one million square miles of the earth's land surface.
Low-lying plains are the most favourable to population settlements. For instance, the plains of North America and Europe are densely populated areas, so is the Ganges Valley in India.
The quality of the soil is yet another geographic determinant of population distribution. There are two kinds of soil, the superficial matter which covers the solid rock below.
The first kind of soil, called the residual soil, is formed by autogenously decomposition and is generally poor in quality. The other kind of soil is that which is transferred from other places by water, ice or wind, and such soil is richer than residual soil.
The deltas in India and Indo-China and the Nile Valley provide examples of this type of rich soil. An approximate estimate has been made of the proportion of the world's soil that is fit for cultivation in the present times.
"In Europe, it is 50 per cent of the land surface, in South America 25 per cent, in Asia 25 per cent, in the North America and Africa each 20 per and in Australia 10 per cent."
Though the quality of the soil was an important determinant of population distribution in the past, modern times, and its role may become less important because mod scientific agricultural technology has devised ways to modify that physiochemical structure of the soil and to make it more fertile, it is sterile or exhausted following over-use and/or wrong use.
It the past, because of lack of such knowledge, degradation of the sort has been known to be the cause of the disappearance of flourish'' civilisations like that of the Mayas in Central America.
The role of energy sources and raw material resources in determining population distribution is less evident in recent times than it was in the past, when the presence of these factors was a fundamental condition for the location of an industry and the consequent demand for labour to man that industry.
Today, beater: of cheap means of transport, it may be possible for industries to be set up in places that are naturally deficient in raw materials.
Among the many kinds of minerals, coal was the first to be used as a source of both heat and motive power, and soon became a symbol of man's control over nature.
More than any other mineral, coed attracts industries and resultant population concentration. Sites of water power are also able to attract population, though not to the same extent as minerals, because electricity can be transmittal over long distances, and industries do not have to be set up at the place where electricity is generated.
The location of a certain place in relation to other areas is another geographic factor which determines how far it will be able to attract population and support it.
For instance, one of the main reasons for the development of industries in and around Pune is the proximity of that area to Mumbai and the excellent modes of transportation that are available.
It has also been observed that "two-third of the inhabitants of the temperate zones live in less than 500 kilometres from the sea, and almost one-half of the remainder live in less than 1,000 kilometres inland."
This review of the geographical factors affecting population distribution clearly indicates that, generally, no factor by itself is responsible for the concentration of population or lack of it.
All these factors are usually inter-related. It is only in some exceptional areas like those with extremely cold climate that the factor of climate itself determines population growth. On the other hand, in some areas all the factors appear to be favourable to high population concentration.
Social and Economic Factors of Population Distribution
Geographers are not unanimous in their opinion that the distribution of population is determined mainly by physical factors. Some are of the view that social and economic factors are more important than physical factors, and that, as society becomes more complex, these physical factors become less important in determining population distribution.
The main reason for this is the fact that, as man gains increasing control over natural phenomena, he is less inclined to accept the natural conditions in which he finds himself, but tends to modify these to suit his own requirements, if other conditions of habitation social and economic conditions are attractive.
The social and economic factors affecting population distribution are: (1) the type of economic activity; (2) the type of technology employed; and (3) social policy.
Type of Economic Activity:
In rural areas, most people make direct use of the surrounding land to support themselves through agriculture, hunting and mining; if land cannot support its population, the surplus moves out.
On the other hand, in urban areas, people do not depend on land for sustenance and, therefore, can live in one area, though they depend on products from other areas. The concentration of population in urban areas is a result of diverse economic activities which cam be carried out in these areas.
When a great variety of economic activity is concentrated in a single area, the result is high population density. These economic activities include wholesale and retail trade, manufacturing, finance and business, and even Government and medical services as well as communication.
Because of the diverse types of economic activities undertaken in urban areas, small land areas can be inhabited by large populations.
Type of Technology:
Various economic activities are interrelated with the types of technology that are used, and jointly they influence population distribution.
It has, however, been pointed out that technology, "has an important influence, for changes in the techniques employed in any type of economic activity may open new areas which formerly held little possibility of human habitation, or render unattractive the sites which formerly were advantageous."
Most countries have strict laws governing immigration, and can, therefore, control the size as well as the internal distribution of their populations.
On the other hand, population distribution within a country is not as easily controlled because, in most countries, citizens have the constitutional right to decide the place of residence within a country. Government however, may and often do and indirectly influence decisions individuals in this matter.
When the Government of India set i steel plants in the public sector at Durgapur, Rourkela people were attracted to these "steel towns" for employment.
Similarly, when the Government of India announced that no licenses would be issued to start new industries or to expand existing industries in Greater Mumbai, the flow of migrants into that metropolis was expected to be arrested at least to some extent.
Demographic Factors of Population Distribution
Though the three demography variables fertility, mortality and migration are themselves determined by social, economic and geographic factors, it is possible to consider them in the light of their influence on population distribution.
Differential fertility and mortality rates lead to differential growth rates which, in turn, lead to changes in the population of a country over a long period of time. Migration, on the other hand, is the most important demographic variable influencing population distribution.
Migration influences population distribution within a country, for people migrate to large industrial centres in search of employment opportunities, thus bringing about population redistribution.
International labour movements take place when there is shortage of labour in one country and a surplus in other countries. Africa provides an example of how international labour movements took place because of the demand for labour which could not be met within the continent itself.
In the latter part of the nineteenth century rich mineral deposits were discovered in Africa. African tribesmen, who lived in their own self-sufficient economies, initially had no incentive to work on wages for European enterprises.
The mining areas, therefore, lacked a sufficient labour force, and most of the workers had to come from other areas, either of the same country or from adjoining countries, and sometimes even from distant countries. In more recent times, several Middle East countries have allowed and have even encouraged immigration from neighboring developing countries to man several skilled well as semi-skilled and unskilled jobs.
The existing population distribution sometimes acts as a demographic factor which attracts the setting up of certain industries, which in turn results in further development of the area and encourages concentration of population.
Many industries have to be set up in proximity with the consumers of their products; conversely, wherever population concentration is great, such industries are set up.
The other reason why industries are set up is population centres is the availability of cheap labour; the location (if such industries, therefore, attracts more persons in search of employment opportunities, and thus leads to a concentration of the population.