Population distribution and resources

The first principle

People live where they can make a living with the least effort and risk, so population follows the resources that support livelihoods: flat land, fertile soil, assured water and a workable climate first, then minerals, trade and jobs. Physical factors set the ceiling on how many people a place can support, while technology, markets and history decide how close a society comes to that ceiling. That is why the Ganga plain holds some of the densest rural populations on earth, while the Himalaya just to its north and the plateau to its south stay thin.

The core

What decides distribution and density

Density is the number of people per square kilometre of area; physiological density is people per unit of cultivable land, which better shows pressure on farmland.

• Relief. Plains and broad valleys are easy to plough, irrigate and connect by road, so they fill up; steep slopes give thin soils, short growing seasons and costly transport.
• Climate. Moderate temperature and reliable rain attract settlement, while hot deserts, cold high latitudes and very wet equatorial forests repel it, which is why large parts of the Sahara, Siberia and the Amazon are nearly empty.
• Soil and water. Young alluvium is deep and renewed by floods, and rivers and aquifers allow two or three crops a year, so river plains and deltas such as the Nile, the Huang He and the Ganga carry dense populations.
• Minerals and energy. Mines pull people into otherwise unattractive places, as in the Chota Nagpur plateau, the Katanga copper belt or the Western Australian goldfields.
• Economic. Industry, ports and services concentrate jobs, so urban corridors such as the eastern United States or coastal China have very high densities.
• Social and historical. Old civilisations, religious centres, security and policy shape where people stay.

World and Indian patterns

About 90 per cent of the world's people live on about a tenth of its land, mostly in the northern hemisphere, in four clusters: East Asia, South Asia, Europe and the north east of the United States. India's density was 382 persons per square kilometre in Census 2011, against a world average of under 60. Within India the pattern follows the same logic: the Ganga plain and the coastal plains of Kerala, Tamil Nadu and West Bengal are dense, while Arunachal Pradesh (17 per square kilometre), the Thar and Ladakh are sparse.

The Ganga basin: land, soil and water

The Ganga basin covers about a quarter of India's area yet supports over 40 per cent of its people, making it among the most densely populated river basins in the world. Three resources explain this.

• Land. The plain is almost flat, falling less than 300 m in the long journey from Haridwar to the sea, so every hectare can be ploughed, canals flow by gravity, and roads and rail are cheap to build.
• Soil. The plain is built of deep alluvium brought down from the Himalaya. Older alluvium on higher ground (bhangar) holds calcareous nodules called kankar, while newer alluvium on the flood plains (khadar) is renewed almost every year by floods and is very fertile.
• Water. Snow and glacier fed rivers such as the Ganga, Yamuna, Ghaghara and Kosi flow all year, the monsoon brings 60 to over 150 cm of rain rising eastwards, and the alluvium forms one of the world's largest aquifers with a shallow water table, so tube wells irrigate easily.

Density rises downstream. In the upper plain of western Uttar Pradesh and Haryana, bhangar dominates and canals and tube wells support wheat and rice. In the middle and lower plain of eastern Uttar Pradesh, Bihar and West Bengal, rain is heavier, khadar is wider and rice supports more people per hectare, so Bihar reached 1,106 and West Bengal 1,028 persons per square kilometre in 2011. Density falls on the fringes: the Himalayan parts of Uttarakhand and Himachal Pradesh, with steep slopes and little flat land, and the plateau parts of the basin in Madhya Pradesh and Jharkhand, with thin red soils and less groundwater.

Dimensions

• Economic. High density on small farms means holdings of under a hectare in Bihar and eastern Uttar Pradesh, low incomes and heavy out migration to cities.
• Environmental. Dense populations draw down groundwater, pollute rivers with untreated sewage and occupy flood plains.

In practice

Problems of the dense Ganga plain

• Fragmentation. Repeated division among heirs leaves tiny, scattered plots that cannot pay for machines or irrigation.
• Floods. The Kosi, "the sorrow of Bihar", shifts course and breaches embankments, as in 2008; about three quarters of Bihar's area is flood prone.
• Groundwater decline. The Central Ground Water Board's 2024 assessment marks many blocks of western Uttar Pradesh and Haryana as over exploited, while arsenic contaminates shallow aquifers in Bihar and West Bengal.
• Pollution. Most towns on the river still discharge part of their sewage untreated; the Namami Gange Programme (Ministry of Jal Shakti, 2014) builds sewage treatment plants under the National Mission for Clean Ganga.

Non farm primary activities and the physiography of India

Primary activities take products directly from nature. Besides crop farming they include mining, quarrying, fishing, forestry, animal husbandry, sericulture and apiculture, and each is tied to a particular landform and climate.

• Mining and quarrying on the peninsular plateau. The plateau is made of ancient igneous and metamorphic rocks with Gondwana coal basins, so the Chota Nagpur plateau holds coal and iron ore, the Aravallis hold lead and zinc at Zawar and marble at Makrana, and the Vindhyan rocks give Kota stone.
• Fishing along coasts and deltas. An 11,000 km coastline and a wide continental shelf on the west coast support marine fishing in Kerala, Gujarat and Maharashtra, while the Krishna Godavari and Ganga deltas, Chilika Lake and the backwaters support inland fishing and shrimp farms. Inland fisheries and aquaculture now give about three quarters of India's fish.
• Pastoralism in mountains and deserts. The Gaddis of Himachal Pradesh and the Bakarwals of Jammu and Kashmir move flocks up to alpine meadows in summer and down to the foothills in winter, a pattern called transhumance; the Raikas of arid Rajasthan herd camels and sheep where crops fail.
• Forest produce in the central highlands. Tribal communities of Chhattisgarh, Odisha, Jharkhand and Madhya Pradesh collect tendu leaves, mahua, sal seeds and lac.
• Salt on tidal flats. The flat, dry Rann of Kutch and the Gujarat coast give most of India's salt by solar evaporation.
• Sericulture and apiculture. Mild plateau climate makes Karnataka the leading mulberry silk state, while forests of Assam host muga and eri silk, and bee keeping thrives in the forested hills and mustard belts.

Rubber: where it grows and what it costs the environment

Natural rubber comes from Hevea brasiliensis, a tree native to the Amazon basin. It needs hot, humid conditions without frost, about 25 to 34°C and over 200 cm of rain spread through the year, so it grows in the equatorial and wet tropical belt, roughly between 10°N and 10°S. Asia grows most of the world's natural rubber, and the leading producers are Thailand, Indonesia, Vietnam, Côte d'Ivoire, China (in Hainan and Yunnan) and India, where Kerala and the adjoining Kanyakumari district give most of the output, with newer planting in Tripura and the north east. Malaysia, once the leader, has shifted much of its land to oil palm.

The environmental issues faced by these countries follow from replacing diverse forest with a single tree crop.

• Forest clearing. Expansion into natural forest in mainland South East Asia, especially Cambodia, Laos and Myanmar, and in West Africa, has cleared millions of hectares.
• Biodiversity loss. A monoculture replaces many layered habitats, so species such as gibbons and hornbills lose forest.
• Soil erosion and water. Young plantations on slopes leave soil bare to heavy rain, and rubber draws heavily on soil moisture in the dry season.
• Chemicals and effluent. Fertiliser and herbicide runoff and acid effluent from latex processing pollute streams.
• Trade pressure. The European Union Deforestation Regulation (EUDR), adopted in 2023, will bar from the EU market rubber grown on land deforested after December 2020; its application has been postponed, but it already forces producers to trace their supply to the plot.

Issues and way forward

• Pressure on the plain. High density on small farms keeps incomes low; rural non farm jobs, food processing and better links to cities, as NITI Aayog has urged for the eastern states, would ease pressure on land.
• Floods and silt. Embankments alone have failed on the Kosi; the Rashtriya Barh Ayog (1980) recommended flood plain zoning and flood forecasting, which most states have not fully adopted.
• Groundwater. Over pumping in the west and arsenic in the east need crop diversification, artificial recharge and safe piped water, as under the Atal Bhujal Yojana (2019) and the Jal Jeevan Mission (2019).
• Pastoral rights. Grazing land is shrinking and pastoralists lose access to forests; recognising community grazing rights under the Forest Rights Act, 2006 protects these livelihoods.
• Sustainable rubber. Certification, agroforestry with intercrops, cover crops on slopes and effluent treatment can keep rubber profitable without clearing forest.

Common confusions

• Density and distribution. Distribution is the pattern of where people are spread; density is how many people live on each unit of area.
• Arithmetic and physiological density. Arithmetic density divides people by total area; physiological density divides them by cultivable land.
• Khadar and bhangar. Khadar is new, fertile flood plain alluvium renewed each year; bhangar is older alluvium on higher ground, above flood level.
• Transhumance and nomadism. Transhumance is a seasonal move between fixed summer and winter pastures; nomads have no fixed base.

For the exam

• Keyword bank: density, physiological density, carrying capacity, alluvium, khadar, bhangar, water table, perennial rivers, fragmentation, arsenic, transhumance, Gaddi, Bakarwal, sericulture, Hevea brasiliensis, monoculture, EUDR.
• Previous year questions: Practise the previous year questions on this topic →
• Use in an answer:
  • Introduction (data): The Ganga basin covers about a quarter of India's area but supports over two fifths of its people, with Bihar's density reaching 1,106 persons per square kilometre in Census 2011.
  • Introduction (textbook): NCERT's human geography sums up the pattern simply: people go where land is flat, soil is fertile and water is assured, and they avoid the rest.
  • Conclusion: The same fertile land, soil and water that drew people to the Ganga plain are now under strain, so the basin's future depends on moving workers off the land rather than adding more onto it.
  • Conclusion: Primary activities are written into the land itself, so policy that respects physiography, from fishing harbours to grazing rights, protects both livelihoods and ecology.