The boundary at the top of a saturated zone is known as the?

• A. Water table
• B. Aquifer
• C. Unsaturated zone
• D. Well

Answer: (A)

The boundary at the top of a saturated zone is the water table. This surface marks the transition where pore spaces in the subsurface go from fully filled with water (below) to containing air and water (above). In the saturated zone, groundwater fills all the voids, while above the water table, the pores are only partly filled—the unsaturated or vadose zone. The water table often follows the shape of the land and shifts up or down with rainfall, evaporation, and pumping. An aquifer is the rock or sediment that stores and transmits groundwater; the unsaturated zone is the layer above the water table; a well is a structure to access groundwater. So, the top boundary of the saturated zone is the water table.