Population explosion phase

Geography glossary

Also called: Phase III (1951-1981) · Topic: Population of India: Distribution, Density, Growth and Composition · NCERT: Class 12, Ch 1 "Population: Distribution, Density, Growth and Composition"

Meaning

The population explosion phase is Phase III of India's population growth (1951-1981). In this phase the death rate fell sharply but the birth rate stayed high, so the population grew very fast and almost doubled in 30 years. It matters because it gave India its very young population and put heavy pressure on food, jobs, housing and schools. These pressures still shape planning and population policy today.

Explanation

How it formed (cause → process → result)

  • Cause 1: deaths fell fast.
  • Planned development began through the Five-Year Plans after 1951.
  • Better medicine, vaccination and malaria control saved many lives.

  • Living conditions improved.

  • Cause 2: births stayed high.

  • Fertility (the number of children women had) was still high.
  • Early marriage was common.

  • The family planning programme started in 1952, but at first it had only a weak effect.

  • Process: the crude death rate (CDR) (deaths in a year for every 1,000 people) dropped quickly. The crude birth rate (CBR) (live births in a year for every 1,000 people) hardly moved.

  • Result: the gap between births and deaths, called natural growth, became very large. The population grew faster than in any other phase.

The numbers

  • Population: 361.0 million (1951) → 683.3 million (1981). It almost doubled in 30 years.
  • Decadal growth (growth over ten years, from one Census to the next):
Decade Decadal growth (%)
1951-61 21.64
1961-71 24.80 (highest ever)
1971-81 24.66 (second highest)
  • Average annual growth rate was about 2.2%.
  • Doubling time (years a population takes to double at its current yearly rate) ≈ 70 ÷ 2.2 ≈ 32 years. This is the Rule of 70.
  • Decadal growth rate formula: g = (P2 − P1) ÷ P1 × 100. P1 is the population at the earlier Census and P2 is the population at the later one.

Its two parts: natural and induced growth

  • Natural growth (births minus deaths) was the main driver.
  • Induced growth (people moving in minus people moving out) added to it. People migrated into India from:
  • Tibet (after 1959)
  • Bangladesh (around 1971)
  • Nepal
  • Pakistan

Place in the demographic transition model

  • Demographic transition model (DTM): a model of how a country moves from high births and high deaths (poor, rural) to low births and low deaths (rich, urban).
  • Phase III fits Stage 2 to early Stage 3:
  • Birth rate: high, only just starting to fall.
  • Death rate: falling fast.

  • Growth: fastest of all stages.

  • It came after Phase II (1921-51), when deaths began to fall, and before Phase IV (after 1981), when births began to fall.

Where it occurs

  • India as a whole, 1951-1981. Every Census of this period (1961, 1971, 1981) showed decadal growth above 21%.
  • Migration sources that added to India's growth: Tibet (after 1959), Bangladesh (around 1971), Nepal and Pakistan.
  • Within India today: the effects of this phase are uneven.
  • Southern and western states such as Kerala and Tamil Nadu have moved further through the transition.

  • North-central states such as Bihar and Uttar Pradesh are still growing fast.

  • World: a high-growth stage like this (DTM Stage 2) is still seen in much of sub-Saharan Africa. Western Europe and Japan passed through it long ago and have finished the transition.

Don't confuse with

  • Steady growth phase (Phase II, 1921-51): deaths fell but growth was only moderate (11.00%, 14.22%, 13.31%). Phase III growth was much faster, above 21% in every decade.
  • Phase of declining growth (Phase IV, after 1981): growth was still high, but it slowed because the birth rate started to fall. In Phase III the birth rate stayed high.
  • "Great Divide" (1921): this is the turning point after which India's population never fell again. 1951 marks the start of rapid growth, i.e. the explosion phase.
  • Mortality-induced growth: the label for Phase II, where growth came from falling deaths. Phase III also had falling deaths, but the drop was much sharper and migration added to it, so growth became explosive.

Prelims Hooks

  • Phase order: Stagnant (1901-21) → Steady growth (1921-51) → Population explosion (1951-81) → Declining growth (after 1981).
  • Highest decadal growth: 1961-71 (24.80%), then 1971-81 (24.66%). Trap: the peak is not 1951-61 (21.64%).
  • Population 361.0 m (1951) → 683.3 m (1981): it almost doubled in 30 years.
  • Annual growth about 2.2% → doubling time about 32 years (Rule of 70).
  • Migration in this phase came from Tibet (after 1959), Bangladesh (around 1971), Nepal and Pakistan. This is induced growth, not natural growth.
  • The family planning programme started in 1952, inside this phase, but at first it barely lowered births.

Mains Points

  • Deaths fell before births:
  • Planned development, medicine, vaccination and malaria control cut deaths quickly after 1951.
  • Early marriage and high fertility kept births high.

  • The large gap nearly doubled the population in 30 years. This explains India's young age structure and the pressure on land, food, jobs, housing and cities (GS-I).

  • Lessons for policy:

  • The weak early effect of family planning (started 1952) shows that targets alone do not lower births.

  • Growth fell after 1981 mainly because of female education and a higher age at marriage. This argues for investing in girls' schooling rather than coercive population control.

  • Lasting effects:

  • The huge young population born in this phase built up population momentum: India keeps adding large numbers even as the growth rate falls.
  • States moved through the transition at different speeds (Kerala and Tamil Nadu ahead, Bihar and Uttar Pradesh behind). This affects seat delimitation, the sharing of Finance Commission funds, and migration from north to south.

Related concepts

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Sources

  1. 1Class 12, Ch 1 "Population: Distribution, Density, Growth and Composition" (primary)