Population forecasting in civil engineering: The shape of the population growth curve commonly observed in demographic studies is identified as which of the following?

Introduction / Context:
Population forecasting is essential for civil engineering projects, particularly in water supply, sanitation, and urban planning. The growth of population often follows a mathematical pattern that can be represented graphically.

Given Data / Assumptions:

• Population grows slowly initially.
• Then growth accelerates rapidly.
• Finally, it slows down and stabilizes.

Concept / Approach:
The population growth curve is generally represented by a logistic function. It begins as slow growth, then accelerates, and eventually stabilizes due to limiting factors such as resources and space. This results in an S-shaped (sigmoidal) curve.

Step-by-Step Solution:

Verification / Alternative check:
This is consistent with logistic growth theory in biology and demography, which civil engineers adapt for long-term planning.

Why Other Options Are Wrong:

• Parabolic curve: Represents quadratic relations, not realistic for long-term population.
• Circular curve: Not meaningful in this context.
• Straight line: Represents arithmetic growth, unrealistic for actual populations.
• None of these: Wrong because S-shaped is the correct established answer.

Common Pitfalls:

• Confusing exponential growth with logistic growth; the latter accounts for limitations.
• Believing all cities grow indefinitely, ignoring saturation effects.

Final Answer:
S-shaped curve