What term describes the boundary that separates the zone of saturation from the zone of aeration underground?

• A. Water Table
• B. Infiltration
• C. Aquifer
• D. Porosity

Answer: (A)

The boundary between the zone of saturation and the zone of aeration is called the water table. It marks the upper surface of the groundwater zone, where below it the pore spaces are fully filled with water, and above it the pores contain air and some water. This surface can rise with heavy recharge or drop with drought and pumping. Understanding the water table helps explain how groundwater moves and where wells will encounter water. The other terms refer to different ideas: infiltration is water entering the soil from the surface, an aquifer is a body of rock or sediment that stores and transmits groundwater, and porosity is the amount of void space in a material.