Which of the following describes the surface where groundwater pressure is equal to atmospheric pressure in an artesian system?

In an artesian system, the surface where groundwater pressure is equal to atmospheric pressure is referred to as the potentiometric surface. This concept is crucial in understanding how confined aquifers function. The potentiometric surface represents the level to which water would rise in a well that taps into the confined aquifer.

In contrast, the piezometric surface is a broader term often used synonymously with the potentiometric surface, but it specifically indicates the hydraulic head of groundwater in the aquifer. The water table, while it indicates the upper surface of unconfined groundwater, differs from the potentiometric surface, as it reflects the pressure of groundwater in unconfined aquifers. The unsaturated zone refers to the area above the water table, where soil and rock can contain both air and water, but does not experience hydrostatic pressure from groundwater.

The correct identification of the potentiometric surface is fundamental for hydrologists and engineers working with groundwater as it informs the behavior of aquifers and groundwater flow patterns.