Question

In a artesian well, when water level falls below the top of confined aquifer, then this type of well is known as ______

(a) well in unconfined aquifer

(b) gravity well

(c) combined artesian gravity well

(d) artesian well

I had been asked this question in an interview for internship.

Origin of the question is Well Hydraulics topic in portion Well Hydraulics of Geotechnical Engineering I

Answer 1

The correct choice is (c) combined artesian gravity well

To explain I would say: In an artesian well, when water level falls below the top of confined aquifer, the flow pattern close to the well is similar to that of gravity well. Hence, it is also known as combined artesian gravity well.