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Difficulty: Very hardPopulation Migration Causes and Effects

An agricultural district in West Africa experiences severe land degradation, compelling a significant portion of its economically active population to relocate. Prior to migration, the district recorded 40,00040,000 children (aged 0–14), 10,00010,000 elderly citizens (aged 65+), and 100,000100,000 working-age adults (aged 15–64). If out-migration permanently reduces the working-age population by 50%50\% while the non-working dependent population remains unchanged, which of the following correctly evaluates the demographic impact on the sending region's dependency ratio and classifies the primary migration driver originating at the rural source?

  1. The demographic dependency ratio doubles from 50%50\% to 100%100\%, driven by an environmental push factor at the origin.Answer
  2. B
    The demographic dependency ratio decreases from 200%200\% to 100%100\%, driven by an environmental push factor at the origin.
  3. C
    The demographic dependency ratio doubles from 50%50\% to 100%100\%, driven by an economic pull factor at the origin.
  4. D
    The demographic dependency ratio remains unchanged at 50%50\%, causing the rural origin to immediately adopt a nucleated industrial settlement pattern.

Answer

The demographic dependency ratio doubles from 50%50\% to 100%100\%, driven by an environmental push factor at the origin.
The baseline dependency ratio is calculated as (Children+ElderlyWorking-Age)×100=(50,000100,000)×100=50%\left( \frac{\text{Children} + \text{Elderly}}{\text{Working-Age}} \right) \times 100 = \left( \frac{50,000}{100,000} \right) \times 100 = 50\%. Following the 50%50\% out-migration of working-age adults, the workforce drops to 50,00050,000, raising the dependency ratio to (50,00050,000)×100=100%\left( \frac{50,000}{50,000} \right) \times 100 = 100\%. Additionally, land degradation is a negative environmental condition at the source region, rendering it a classic push factor.

Step-by-Step Solution

1
Calculate the initial dependent population and baseline dependency ratio.
Total initial dependents = 40,000+10,000=50,00040,000 + 10,000 = 50,000. Baseline Dependency Ratio = (50,000100,000)×100=50%\left( \frac{50,000}{100,000} \right) \times 100 = 50\%.
Dependency ratio measures the ratio of non-working dependents (aged 0–14 and 65+) per 100 working-age people (aged 15–64).
2
Calculate the new working-age population after out-migration and compute the updated dependency ratio.
New working-age population = 100,000×(1−0.50)=50,000100,000 \times (1 - 0.50) = 50,000. New Dependency Ratio = (50,00050,000)×100=100%\left( \frac{50,000}{50,000} \right) \times 100 = 100\%.
Out-migration reduced the denominator (workforce) by half while leaving the numerator (dependents) constant.
3
Identify the nature of the migration driver originating at the rural area.
Severe land degradation at the place of origin is an unfavorable condition forcing people away, which is an environmental push factor.
Push factors are negative conditions at the place of origin that compel individuals to move away.

Key Concept

Demographic Dependency Ratio and Push-Pull Migration Factors
Estimated Time:2m 0s
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Topics

Population Migration Causes and Effects

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