InTeGrate Modules and Courses >Water Science and Society > Student Materials > Module 6: Groundwater Hydrology > 6.2 Aquifer Processes and Dynamics > Effects of Pumping Wells
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These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
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Initial Publication Date: March 31, 2017

Effects of Pumping Wells

Groundwater is accessed for use either by pumping from wells drilled into the aquifer in the subsurface (Figure 33), or by developing natural springs, where the potentiometric surface intersects the land surface (Big Spring in Bellefonte, PA is one example of a relatively large spring that is used for municipal supply). Although springs are relatively inexpensive to develop, they are not always present, nor are the flow rates always sufficient to support demand. As a result, most groundwater extraction occurs by pumping at wells, or in many cases from "fields" of wells concentrated in a small area.

Cones of Depression: Pumping at a well, or at a wellfield, pulls water toward the well from all directions – in other words, it induces radial flow. In doing so, pumping causes a reduction in hydraulic head, known as drawdown, and generates a cone- or funnel-shaped depression (Figure 35). This perturbation to the potentiometric surface is called a cone of depression. The reduction in hydraulic head is, in fact, what drives groundwater flow to the well (in the down-gradient direction), as shown in the example from Long Island in Figure 36.

Both the width and the depth of the cone of depression scale with the rate of pumping, the aquifer permeability and storativity, and the duration of pumping. In general, larger cones of depression result from larger pumping rates, higher permeability or lower storativity, and longer elapsed time. If the cones of depression from two separate pumping wells grow large enough that they overlap, it is known as well interference. When well interference occurs, the drawdown is additive. The result is that drawdown is accelerated when cones of depression from multiple extraction wells interact; this is generally not desirable, and is one important consideration in the design, permitting, and operation of wells.

Not only does the cone of depression draw water to the well, but if the pumping rate is large enough or pumping is sustained for a long time, it can reverse the natural hydraulic gradient hundreds of meters to several tens of km away from the well(s). In some cases, this may result in interception of groundwater that would normally feed a stream or river as baseflow, and even in interception of streamflow itself by inducing infiltration in the stream bed or banks (Figure 35B). In other cases, large cones of depression (up to a few miles wide!) associated with industrial or municipal well fields may reverse regional topographically-driven hydraulic gradients and lead to problems like saltwater intrusion (Figure 35B).


These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
Explore the Collection »