Penn StateNASA

Cone of Depression

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Schematic showing development of a cone of depression as a result of heavy pumping
Schematic showing development of a cone of depression as a result of heavy pumping
Credit: USGS

Overuse of groundwater does not have to lead to major land subsidence before it causes problems. On a more local scale, over-pumping can result in lowering of the water table in a process called “cone of depression,” a generally concentric pattern of water table drawdown. Such over-pumping often results from industry or agriculture but individual landowners often feel the repercussions.

Alternatively, a cone of depression can result when housing developments, particularly those with many small lots, use wells for water supply. A cone of depression can drastically decrease water pressure, or worse, lower the water table below the level of the well, leaving a home or a farm without a water supply. The only solution for this is to drill the well deeper, which can be an expensive proposition for an individual landowner. Left unchecked, a cone of depression can modify the flow of groundwater as well as the distribution of pollutants,