An unconfined aquifer has which feature?

• A. A water table that is always at ground level and never changes.
• B. A water table lies below the surface at all times in unconfined aquifers.
• C. An unconfined aquifer has a water table that is open to the surface and recharge occurs directly from the surface.
• D. An unconfined aquifer is sealed by impermeable layers.

Answer: (C)

An unconfined aquifer is defined by a water table that forms the upper surface of the saturated zone and is open to the surface, so recharge can occur directly from precipitation and surface water. There is no impermeable layer above it, which lets water infiltrate from the ground surface to replenish the aquifer. This means the water table can rise or fall with rainfall, evaporation, and pumping. The other descriptions don’t fit: the water table isn’t fixed at ground level and never changes; it isn’t always below the surface; and an impermeable cap above an aquifer would make it confined, not unconfined.