The growth of population in a region depends upon fertility, mortality and migration.
Fertility or the birth rate is measured in terms of total number of live births per thousand population per year. Generally, the fertility rate is affected by various social, economic and demographic factors.
Mortality or the death rate is measured in terms of total number of deaths per thousand population per year. The difference between these two rates (ertility and mortality) is called the natural growth rate.
Migration refers to the movement of people from one area to the other or from one country to another. The rate of migration affects the growth of population of a region by increasing or decreasing the number of people living there.
The growth rate of population may be positive or negative. A positive growth rate of population means an increase in the number of people living in a region, whereas negative growth rate means declining population. A positive growth rate occurs when the number of births and in migration exceeds the number of deaths and out migration; the negative growth rate means just opposite to positive growth rate.
The district level analysis reflects that there are as many as 19 districts where the growth rate is very high i.e. more than fifty percent. On the other hand there are 58 districts where growth rate is very low i.e. less than ten percent. Out of the 19 very high growth rate districts five belong to Nagaland and four to Delhi.
Similarly, out of 58 very low growth rate districts, as many as forty districts are in the southern part of India. Out of these forty districts as many as twenty are in Tamil Nadu, eleven in Kerala, five in Andhra Pradesh and four in Karnataka.
Higher growth rates are visible in almost the entire Indo-Gangetic plains extending from Haryana in the west to West Bengal in the east. High growth rates are also observed in the regions north of Satpura Ranges, spreading across the Malwa plateau, entire Rajasthan including the great Indian desert, Western Maharashtra and parts of North-Eastern states.
On the other hand relatively low growth rate is observed in Godavari basin, Chhatisgarh plains, Chhotanagpur plateau and western part of West Bengal and Orissa. Very low growth rates are observed in Punjab, Uttarakhand, and in the southern regions of the Deccan plateau.
The population growth can be broadly grouped under the following four categories:
1. Before 1921 the increase in population was sporadic, irregular and slow. This was mainly due to high birth and death rate. Therefore, the natural growth was insignificant. In 1911-21 the absolute increase declines marginally due to famines, epidemics, etc. After 1921 the population has been increasing. Therefore, 1921 is known as demographic divide in the population study of India.
2. Since 1921 to 1951 there was a steady increase in population. This is because of steady decline in death rates. The decline was mainly due to improvement in sanitation and medical facilities. Other factors which helped were development in road facilities which helped in meeting the exigencies of food shortage and substantial improvement in agricultural economy. Therefore, the population growth during this period was known as mortality induced growth.
3. This is a very crucial phase as far as population growth of India is concerned. The population was almost doubled during these three decades. During this period there was a rapid decline in death rate whereas the decline in birth rate was marginal. Birth rate was reduced from 41.7 to 37.2 whereas death rate was reduced from 22.8 to 15.0 during this period. Therefore, the difference between birth rate and death rate was very high and as a result natural growth rate remains very high. This was due to acceleration in developmental activities further improvement in medical facilities, improvement in living conditions of the people, etc. This period of growth is termed as fertility induced growth.
4. In the last two decades i.e. 1981-91 and 1991-2001, the rate of growth started declining gradually. It signals the beginning of a new era in the demographic history of India. During this period birth declined significantly, from 37.2 in 1971-81 to 24.8 in 1991-2001. Whereas the decline in death rate continued in a slower rate. The death rate has declined from 15.0 to 8.9 during this period. This declining trend is a positive one and may be attributed to effective government role in promoting family welfare programmes and peoples awareness.