Weathering and Landforms Topics

Groundwater (Part 5)

Human Activities and Groundwater

• Human activities can harm groundwater by polluting it, over-pumping it, or causing saltwater encroachment.


• Seepage from toxic materials or hazardous waste can contaminate groundwater.

Trash dumped into a sinkhole. (Photograph by Robert Whisonant)

The photograph above shows a trash-filled sinkhole.  Pollutants can leach out of this trash and seep to the groundwater.  Such dumping is now illegal, but older illegal dumps can still cause groundwater pollution. 


• Over-pumping causes the water table to lower around a well, forming a cone of depression.

Cones of depression
(Diagram courtesy of the United States Geological Survey)

If pumping occurs at a faster rate than groundwater can move into the aquifer, cones of depression form at pumping wells.  If these cones grow very large or overlap, they can lower the groundwater levels all around the aquifer. 

Saltwater Encroachment

• Saltwater encroachment occurs when sea water is drawn into freshwater aquifers in coastal areas.