Water Demand Estimation MCQ with answer and solution

Concept

The arithmetical increase method suits large, old cities where growth is steady and nearly constant.

Formula

P_n = P₀ + n × x̄

Step-by-step solution

1. Large, old cities are already well developed. 2. Their population grows by almost the same amount each decade. 3. A constant increase per decade is the arithmetical increase method. 4. So the answer is (C).

Explanation

In large, old cities, growth has slowed and become steady. The increase per decade is almost constant, so the arithmetical increase method gives a good forecast. It may give slightly low values, which is acceptable for such cities.

Why the other options are wrong

A: Comparative graphical method uses data from other similar, larger cities and is not the standard method for a large city itself. B: Simple graphical method only extends the past curve and is less reliable. D: Geometrical increase method suits young, fast-growing cities and gives very high values for large cities.

Shortcut

Old and large city means arithmetic. Young and growing city means geometric.

Common mistake

Choosing the geometrical method because the city is big. It overestimates population for stable cities.