Density is a very important parameter of population concentration. It is defined as number of persons living per unit area and expressed as persons per square kilometre.
Census of2001 shows that the average density of population of India is 324 persons/ sq km. In 1991 it was 267 persons/ sq km. Therefore, 57 persons have been added per square kilometre to the already high concentration.
This puts tremendous pressure on the resource base, infrastructure and adversely affects the quality of life. The pattern of increase is very uneven. Urban areas, industrial belts and the Indo-Gangetic plain ban experienced a greater increase than the rest of the country.
West Bengal is the most densely populated state of India with an average density of 904 persons/sq. km. The puts additional pressure on the fragile ecosystem of this region because post green revolution, the environment is already in a very advanced state of degradation. Mo number of people in the same region means a larger ecological footprint. Larger ecological footprint means a greater level of unsustainability both in terms of environment and resource utilization.
Areas of High Density
The high density of population is found in Indo-Gangetic plain which includes the states of West Bengal, Bihar, Uttar Pradesh, Haryana, Punjab and Union Territories of j Delhi and Chandigarh. West Bengal is still most thickly populated where the population density has gone up from 767 persons per sq km in 1991 to 904 persons per sq km in 2001.
However, among major states, Bihar is now the second most densely populated state with 880 persons per sq km and has pushed Kerala to the third position with 819! Persons per sq km, which had 749 persons per sq km in 1991.
The pressure on land in the entire Indo-Gangetic plain which extends up to Hoogly basin in the east is quite I evident from the fact that West Bengal, Bihar and Uttar Pradesh experience high density of population and this belt owes its high density mainly to the level land tract, alluvial soils, water for irrigation, all factors conducive to good agriculture and also because of long history of settlement.
In south, the density is very high in Malabar region, and Tamil Nadu uplands because of highly intensive agriculture based on rice cultivation and industry associated with processing of products from plantation crops.
Urban development of relatively high order in this region has also been responsible for high level of density in peninsular region. Kerala is also a very fertile region with long history of human habitation.
Up till 1981, it was the most densely populated state. It is the only state in South India which has dispersed settlements and a more or less even distribution of population in the entire country side.
Union Territories have a high density of population, which is more than 1500 persons per sq km., mainly because of high degree of urbanization and industrial development experienced in these regions.
It has led to the migration of people from different parts of the country to these urban dusters. Delhi with 9249 persons per sq km has the highest density among the states and UTs.
Areas of Moderate Density
This category includes the states of Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, Andhra Pradesh, Orissa, Assam, Maharashtra and Gujarat. Moderate densities are characteristic of those areas where the agriculture is handicapped by undulating topography and scarcity of water for irrigation, but where urban areas and industrial development has helped the region in supporting moderate density.
These mainly constitute the transitional areas between high density and low-density area.
Here among the states with moderate density the population density of Maharashtra has gone up from 256 persons per sq km in 1991 to 314 persons per sq km in 2001.
Areas of Low Density
Most of the states in this category arc the Himalayan states, namely Jammu and Kashmir, Himachal, Uttranchal, Nagaland, Manipur, Meghalaya, Sikkim, Mizoram and Arunachal. Only exceptions are Chhattisgarh and UT of Andaman and Nicobar Islands.
All the Himalayan states are sparsely populated because of hilly and inhospitable terrain, harsh climate and steep slopes. Chhattisgarh and Andamans are very densely forested regions with not very fertile soils and population comprising of hunting- gathering, forest dwelling tribes. Yet, when compared to 1991, the density of population has certainly gone up.