What is a cone of depression?

• A. A localized lowering of the water table around a pumped well, caused by groundwater pumping exceeding recharge.
• B. A rising water table around a pumped well.
• C. A surface depression due to evaporation.
• D. An area of groundwater warming.

Answer: (A)

A cone of depression occurs when groundwater is pumped faster than it can be recharged, causing the water table to drop locally around the pumped well. As water is removed, the surrounding groundwater flows toward the well, pulling the water table down more near the center and less far away, which in cross-section looks like a cone dipping toward the well. This is a sign of drawdown from pumping. The other options describe a rise in the water table, surface evaporation features, or groundwater warming, none of which match the effect of sustained pumping on the water table.