World Population & Human Settlements – NDA Geography Notes

Introduction

The Earth currently supports about 8 billion people — and that number continues to grow, though at a slowing rate. These people are not evenly distributed. Some parts of the world — river valleys, coastal plains, fertile agricultural regions — are densely packed. Other parts — deserts, high mountain ranges, dense rainforests, polar regions — are almost empty.

Understanding where people live and why, how population grows and changes over time, and what kinds of settlements humans create — this is the focus of this chapter.

For NDA, this chapter is lightly to moderately tested. Questions tend to be conceptual — what is physiological density, what does the demographic transition model describe, what is demographic dividend, what does a population pyramid show. These test understanding of concepts rather than pure memorisation.

Understand the Topic

Part 1 — World Population Distribution

Where Do People Live?

About 90% of the world’s population lives in the Northern Hemisphere. The most densely populated regions are:

East Asia — China, Japan, South Korea: dense agricultural populations in river valleys and coastal plains.

South Asia — India, Bangladesh, Pakistan: one of the most densely populated regions on Earth.

Southeast Asia — Java (Indonesia), Philippines, Vietnam: fertile agricultural lands supporting intensive cultivation.

Western Europe — historically industrialised and urbanised.

Eastern North America — the megalopolis corridor from Boston to Washington.

Sparsely populated regions:

• Polar and sub-polar regions (too cold)
• Tropical rainforests (difficult to farm)
• Deserts (too dry)
• High mountain ranges (too rugged and cold)

Why South and Southeast Asia have the largest concentration of peasant population:

South and Southeast Asia have the largest concentration of peasant population globally because intensive subsistence farming is practised in the region — the fertile river valleys and deltas support intensive wet rice cultivation which requires large amounts of labour per unit of land. This creates extremely dense rural populations. [NDA tested via CDS]

Types of Population Density

Arithmetic (Crude) Density:
Total population ÷ Total land area.

This is the simplest and most commonly used measure. It gives a number — people per square kilometre. But it can be misleading — Egypt has a lot of desert, so the crude density underestimates how crowded the inhabited Nile Valley actually is.

Physiological Density:
Total population ÷ Cultivable (arable) land area.

This measures how many people each unit of farmable land must support. It gives a better picture of the pressure on agricultural resources. [NDA 2022-II | NDA tested via CDS]

Physiological density is preferable to arithmetic density as an index of population density — because physiological density is based on arable land while arithmetic density is based on total area. The second statement correctly explains the first. [NDA tested via CDS]

Number of people per unit area of arable land = physiological density. [NDA tested via CDS]

Agricultural Density:
Agricultural population ÷ Cultivable land area.

Measures the number of agricultural workers per unit of arable land — useful for understanding farming pressure. [NDA 2022-II]

All three density definitions are correct: [NDA 2022-II]

1. Physiological density = total population ÷ net cultivable area — TRUE
2. Agricultural density = total agricultural population ÷ net cultivable area — TRUE
3. Population density = total population ÷ total area — TRUE

Population Calculation

NDA 2014-II tested a simple population calculation:
Beginning population = 5,000. Births = 250. Deaths = 60. Immigration = 30. Emigration = 15.
End of year population = 5,000 + 250 − 60 + 30 − 15 = 5,205. [NDA 2014-II]

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Sex Ratio

Sex ratio in India is expressed as females per thousand males.

At the world level, sex ratio is about 102 males per 100 females — there are slightly more males than females globally.

In Asia, sex ratio is low — fewer females relative to males — due to son preference in some countries. The statement that Asia has a HIGH sex ratio (implying more females) is incorrect. [NDA tested via CDS]

Part 2 — Demographic Transition Model (DTM)

The Demographic Transition Model describes how a country’s birth rates and death rates change as it develops economically. It has four main stages.

Stage 1 — Pre-Industrial (High Stationary):
Both birth rate and death rate are HIGH. Death rate is high because of disease, poor sanitation, famine, and lack of medical care. Birth rate is high because of cultural tradition and high infant mortality. Population growth rate = LOW (births and deaths nearly balance).

Stage 2 — Early Industrial (Early Expanding):
Death rate falls rapidly — due to improved medicine, sanitation, and food supply. Birth rate remains HIGH — cultural change is slow. Population growth rate = HIGH (big gap between high births and falling deaths). This is the stage of explosive population growth.

Stage 3 — Late Industrial (Late Expanding):
Birth rate begins to fall — due to urbanisation, women’s education, and access to contraception. Death rate continues to fall but is already low. Population growth rate = SLOWING.

Stage 4 — Post-Industrial (Low Stationary):
Both birth rate and death rate are LOW. Population growth rate = LOW (near zero). Most developed countries are in this stage.

Demographic transition model provides a model for examining the relationship between economic development and natural population change. [NDA 2015-I]

Demographic gap = the difference between the birth rate and the death rate — which determines the natural rate of population growth. [NDA tested via CDS]

Demographic Dividend

Demographic dividend refers to the economic growth potential that arises when a country’s working-age population (15–64 years) is large relative to the dependent population (children below 15 and elderly above 64).

When a country transitions from high to lower birth rates, a window exists when the working-age population is large (children born during high birth rate era have grown up) while the number of young children is falling. This creates a window for economic growth — more workers, fewer dependents.

Population dividend refers to a youthful age structure of a population. [NDA tested via CDS]

Demographic dividend relates to an increase in working-age population. [NDA tested via CDS]

India is currently experiencing its demographic dividend — a large working-age population that, if properly skilled and employed, can drive significant economic growth.

Demographic dividend = large WORKING-AGE population. It does NOT refer to a large elderly population. [NDA tested via CDS]

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Population Pyramid

A population pyramid is a graphical representation of a population’s age and sex structure. It shows the proportion of males and females in different age groups.

Variables displayed in population pyramids: age groups AND sex indicators (male and female). [NDA tested via CDS]

Types of population pyramids:

• Broad base, narrow top = young population; high birth rate; developing countries
• Uniform/Rectangular = stable population; equal proportion in each age group
• Narrow base, broader middle = aging population; low birth rate; developed countries

Primate City:

Mark Jefferson developed the concept of the primate city — the idea that in many countries the largest city is disproportionately large compared to the second city. Examples: Bangkok (Thailand), Lima (Peru), Nairobi (Kenya). [NDA tested via CDS]

Part 3 — Human Settlements

What is a Settlement?

A settlement is any place where people live — from an isolated farmhouse to a megacity. Settlements reflect the physical geography of their location, the economic activities of their inhabitants, and the history of the region.

Two main types:

• Rural settlements — villages and hamlets; dependent on agriculture and natural resources
• Urban settlements — towns and cities; dependent on industry, trade, and services

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Types of Rural Settlements

Clustered (Nucleated) Settlement:
Houses grouped closely together in a compact pattern. Common in agricultural plains. Most common settlement type globally.

Dispersed Settlement:
Houses spread far apart across the landscape. Common where people need large landholdings (pastoral farming) or in difficult terrain.

Linear Settlement:
Houses arranged in a line — along a road, river, or coast.

Dry Point Settlements:
Settlements located on elevated ground to avoid flooding — in areas prone to waterlogging such as river floodplains and coastal marshes. People deliberately settled on higher, drier spots to avoid floods while maintaining access to water and fertile farmland.

Dry point settlements are common in DELTAS. [NDA 2009-I]

Important World Cities on Rivers

Montreal is located on the banks of the River St Lawrence in Canada. [NDA tested via CDS]

Buenos Aires and Montevideo are situated across the banks of the River Plate (Río de la Plata) — the wide estuary between Argentina and Uruguay. [NDA tested via CDS]

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Pastoral Nomads

Several NDA questions ask about specific nomadic groups and their locations.

Tuareg:
A pastoral nomad group living in the Sahara Desert of North Africa — particularly Mali, Niger, Algeria, Libya. [NDA 2014-I]

Yakuts (Sakha):
Nomadic herders of the Tundra regions of Siberia, Russia. [NDA 2015-I]

Sami (Lapps):
Indigenous people of Lapland — the northern part of Scandinavia above the Arctic Circle. Traditionally reindeer herders.

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Half the World’s Population — Six Countries

Half of the world’s population lives in just six countries: China, India, United States, Indonesia, Brazil, Pakistan. [NDA tested via CDS]