Groundwater Hydrology MCQ with answer and solution

Concept

Unconfined Aquifer

Formula

Q = πK(h₂² - h₁²) / ln(r₂/r₁) (Dupuit's formula for steady flow in an unconfined aquifer)

Step-by-step solution

This is a direct conceptual question, so no calculation is required:1. Identify that the upper boundary of an unconfined aquifer is defined by the water table. 2. Recognize that because the water table is free to rise and fall, an unconfined aquifer is also known as a water table aquifer.

Explanation

An unconfined aquifer is also known as a water table aquifer because its upper boundary is formed directly by the water table. Since there is no impermeable layer above it, the water surface inside the aquifer is at atmospheric pressure and can freely rise or fall.

Shortcut

Think of "Unconfined" as open/free at the top, meaning its top boundary is directly the free Water Table (Unconfined = Water Table Aquifer).

Common mistake

Many students confuse an unconfined aquifer with an artesian aquifer (Option D), which is actually a confined aquifer where water is under pressure, rather than recognizing that an unconfined aquifer is bounded by the water table (Option B).