Which statement describes the zone of saturation?

• A. The zone where all pore spaces are filled with water
• B. The zone with air and water
• C. The surface water
• D. The aquifer

Answer: (A)

The zone of saturation is the portion of the subsurface where all pore spaces are filled with water. This region lies below the water table, which marks its upper boundary; above the water table, pore spaces contain both air and water in the unsaturated (vadose) zone. Surface water isn’t about pore filling, and an aquifer is the permeable layer that can store and transmit groundwater, not the exact definition of this zone. So the statement that describes all pore spaces being filled with water correctly identifies the zone of saturation.