The most common sort among the calculations of population density is as defined by the number of persons per square kilometre. Calculations of population density depict the concentration of population over certain spatial units, and the Census of India uses number of persons per square kilometre as its principle method with which to measure population density.
However, given the compelling influence of geography over the spatial distribution of populations, geographical units can also be considered as valid units in calculations of population density.
As per the 2011 Census, GoI, the population density of India in terms of number of persons per square kilometre had reached 382 persons per sq km as compared to 325 persons per sq km in the 2001 Census. This represents a rise by about 57 people per sq km of India on average as compared to the last Census. Only about 2.4 per cent of the world’s total area comprises India, but Indians make up for 17.5 per cent of the world’s population. As per the 1901 Census, the population density of India was just 77 persons per sq km. In fact India’s population density fell between the 1911 to the 1921 Census by 1.2 per cent. Since then India’s population density has been steadily rising with much higher percentage growths.
Fig: Population Density (persons per sq km) of India as per Census 2011
Urban states and union territories in India have the highest population density among states and union territories in terms of this measure, with the most being in Delhi as per the 2011 Census, followed by Chandigarh, Puducherry, and Daman & Diu in that order. Delhi has a population density of 11,297 persons per sq km. Among the bigger states in terms of land area, Bihar has the highest population density of 1,102 persons per sq km and occupies the 6th rank, followed by West Bengal, Kerala and Uttar Pradesh in that order. The lowest population density in India in terms of persons per sq km is present in Arunachal Pradesh with 17 persons per sq km. In terms of states having the lowest population density, Arunachal Pradesh is followed by the Andaman & Nicobar Islands, Mizoram and Sikkim as per the 2011 Census.
Population Density by Geographical Regions
The Census of India has made attempts to also map population density in terms of geographical regions. In this 6 regions across India have been identified for measurements of population density.
The northern region includes the 7 states and union territories of Jammu & Kashmir, Himachal Pradesh, Punjab, Chandigarh, Haryana, Delhi and Rajasthan and has a population density of 267 persons per sq km as per the 2011 Census. The central region includes the 4 states of Uttarakhand, Uttar Pradesh, Chhattisgarh and Madhya Pradesh and has a population density of 417 persons per sq km.
The eastern region includes the 6 states and union territories of Bihar, Sikkim, West Bengal, Jharkhand, Odisha and the Andaman & Nicobar Islands and has a population density of 625 persons per sq km. The north-eastern region includes the 7 states of Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Meghalaya and Assam and has a population density of 176 persons per sq km.
The western region includes the 4 states and union territories of Gujarat, Daman & Diu, Dadra & Nagar Haveli and Maharashtra and has a population density of 344 persons per sq km. The southern region includes the 7 states and union territories of Andhra Pradesh, Karnataka, Goa, Lakshadweep, Kerala, Tamil Nadu and Puducherry and has a population density of 397 persons per sq km.
The highest population density thus was in the eastern region that included the very densely populated states of Bihar and West Bengal. The lowest population density was observed for the north-eastern region in the 2011 Census. Since the 2001 Census the highest rate of increase in population density has been observed for the central northern and eastern regions while lower increases in population density have been observed for the western, southern and the north-eastern region. The highest rate of increase was observed for the central region with 20.31 per cent while the lowest rate of increase was observed for the southern region with 12.58 per cent.
This distribution tends to agree with the Heartland Theory in geopolitical theory that looks at political development as based around central areas called the heartland areas. In this the Gangetic Plain emerges as the demographic heartland in India, with the highest population density present the central region and also in the eastern region comprising Bihar and West Bengal among states. A higher population density however, increases the load on natural resources and the environment, especially in the case of waste in urban areas, which can severely pollute the environment.
Physical Factors Affecting Population Density in India
The geography of India can play a vital role in influencing the population density of India. The physical factors can include topography, climate, soil conditions, etc.
Human settlements many a time are established around topographical features. Whether it were the hilltop villages in early Nagaland that would offer defence against attacks by enemy tribes or settlements close to water sources such as the important cities next to great rivers such as Delhi and Kanpur, topography has played a decisive role in agglomeration of settlements and population density.
Take Santa Cruz del Islote Island, Colombia for example. The island has a population density of 103,917 persons per sq km, making it in terms of averages one of the most densely populated places in the world. The most densely populated single place in the world however, is Dharavi slum in Mumbai, India, with a total area of 1.7 to 2.2 sq km and a population density of 300,000 persons per sq km. Its overcrowding can also be attributed to Mumbai’s unique topography that allows the city limited area to expand spatially. The Indo-Gangetic Plains are a region with a benign topography and plentiful water with fertile land and thus has a very high population density whereas the nationally remote, mountainous and forest-covered Arunachal Pradesh has a low population density.
Climatic factors such as the amount of precipitation can heavily influence the spatial distribution of population. In the dry and largely arid state of Rajasthan for example, which can also exhibit extremes of temperature, population density is quite low. Temperature thus can also influence the spatial distribution of populations. In India’s Himalayan region for example, the extremely cold and wet conditions tend to discourage high population density. Wherever, extremes of climate occur, it can be said that population density generally tends to be less. With climate change on the horizon, extremities of climate could witness an increase in certain regions.
Although contemporary society is highly industrialized with increasing rates of urbanization, in India about 75 per cent of the total population live in villages and practice mainly agriculture. Agriculture and allied activities meets the livelihood needs of these people, which is heavily dependent on the fertility and other qualities of the soil. Due to alluvial soil being present for example, the northern plains, coastal regions and also the deltaic regions of India tend to have high population densities.
This could point towards other methods of measuring population density such as population density in terms of population occupying agricultural land, or population density in terms of climatic factors like aridity, mean temperatures and precipitation. Many correlations have been mentioned between the distribution of population densities across geographical regions and geographical determinants of the spatial distribution of population. In this other than simply persons per sq km, geographical units such as population density in terms of geographical factors such as precipitation, soil fertility, availability of water, etc are also equally valid.