What is the Cone of Depression?

• A. Ground water under the influence of the pump flows toward the well from every direction
• B. A localized inverted cone-shaped drop in the water table that develops around a groundwater well when it is being pumped
• C. The water table rises near a pumped well
• D. It is a surface water feature unrelated to pumping

Answer: (B)

When you pump groundwater from a well, the hydraulic head around the well drops, pulling water toward the pump from the surrounding formation. This creates a localized, inverted cone-shaped depression in the water table (or potentiometric surface) with its apex at the pumping well. The water around the well flows radially inward, so the cone forms as the drawdown extends outward from the well. The size and sharpness of this cone depend on pumping rate, aquifer properties, and time, and it can be more pronounced in confined aquifers or visible as a surface decline in unconfined aquifers. It is not a rise in the water table and it is directly linked to the act of pumping.