Geography: Class 12 (Part 1) — Chapter 2: The World Population: Distribution, Density and Growth

Patterns of Population Distribution

The population of the world is highly unevenly distributed. The term Population Distribution refers to the way people are spaced over the earth's surface.

Broadly, 90 per cent of the world population lives in about 10 per cent of its land area.
The 10 most populous countries contribute about 60 per cent of the world's population. Out of these, 6 are located in Asia (China, India, Indonesia, Pakistan, Bangladesh, Russia).

Density of Population

Density of Population is the ratio between the number of people and the size of land. It is usually measured in persons per square kilometer.

$$\text{Density of Population} = \frac{\text{Population}}{\text{Area}}$$

For example, if Region X has an area of 100 sq km and a population of 1,50,000, its density is calculated as:

$$\text{Density} = \frac{1,50,000}{100} = 1,500 \text{ persons/sq km}$$

Factors Influencing Population Distribution

I. Geographical Factors

Availability of Water: People prefer areas with fresh water for drinking, agriculture, and industries. River valleys are densely populated.
Landforms: Flat plains and gentle slopes favor agriculture, transport, and industries. The Ganga Plains are densely populated, while the Himalayas are scarcely populated.
Climate: Extreme climates (hot/cold deserts) are avoided. Pleasant climates like the Mediterranean region attract population.
Soils: Fertile loamy soils support intensive agriculture.

II. Economic Factors

Minerals: Mineral-rich areas attract industries and employment (e.g., Katanga-Zambia copper belt in Africa).
Urbanisation: Cities offer better employment, education, medical facilities, and transport, leading to rural-to-urban migration.
Industrialisation: Industrial belts provide job opportunities (e.g., Kobe-Osaka region of Japan).

III. Social and Cultural Factors

Places of religious or cultural significance attract people. Conversely, social and political unrest drives people away.

Population Growth & Components of Change

Basic Concepts of Population Geography

Growth of Population: Change in population in a particular area between two points of time.
Growth Rate of Population: Population change expressed in percentage.
Natural Growth: Difference between births and deaths.
$$\text{Natural Growth} = \text{Births} - \text{Deaths}$$
Actual Growth: Takes migration into account.
$$\text{Actual Growth} = \text{Births} - \text{Deaths} + \text{In-Migration} - \text{Out-Migration}$$
Positive Growth: When birth rate is higher than death rate or people migrate permanently to a region.
Negative Growth: When population decreases due to falling birth rates or high out-migration.

Components of Population Change

There are three main components: Births, Deaths, and Migration.

Crude Birth Rate (CBR): Expressed as number of live births in a year per thousand of population.
$$CBR = \frac{B}{P} \times 1000$$
Where $B$ = live births during the year, $P$ = estimated mid-year population.
Crude Death Rate (CDR): Expressed as number of deaths in a year per thousand of population.
$$CDR = \frac{D}{P} \times 1000$$
Where $D$ = number of deaths, $P$ = estimated mid-year population.

Migration

Movement of people from a Place of Origin (shows population decrease) to a Place of Destination (shows population increase).

Immigration: Migrants who move into a new place.
Emigration: Migrants who move out of a place.

Push Factors (Force people to leave)	Pull Factors (Attract people)
Unemployment, poor living conditions, political turmoil, unpleasant climate, natural disasters, epidemics, socio-economic backwardness.	Better job opportunities, improved living conditions, peace and stability, security of life and property, pleasant climate.

Demographic Transition Theory

Demographic Transition Theory describes and predicts the future population of any area. It explains the transition from high births and deaths (rural, agrarian, illiterate) to low births and deaths (urban, industrial, literate) through a Demographic Cycle.

Stage	Characteristics	Examples / Context
Stage I	High fertility and high mortality. Slow population growth. Mostly agrarian society, low technology, low life expectancy.	Rainforest tribes, Bangladesh (historically), all countries 200 years ago.
Stage II	High fertility initially, but declines over time. Mortality rate reduces significantly due to improvements in sanitation and health. High net population addition.	Peru, Kenya, Sri Lanka.
Stage III	Both fertility and mortality decline considerably. Population becomes stable or grows slowly. Highly urbanised, literate, and technically advanced.	Canada, Japan, USA.

Population Control Measures

Family Planning: Spacing or preventing the birth of children. Measures include propaganda, free availability of contraceptives, and tax disincentives for large families.
Malthusian Theory (1798): Thomas Malthus stated that population increases faster than food supply. Any further increase leads to a population crash caused by famine, disease, and war.