What is an Aquifer?
Renewal & Removal
of Groundwater - Page 1
Removal of Groundwater page 2
What is it?
U.S. Geological Survey, Paul Barlow.
"(Figure modified from Cooper, H. H., 1964, A hypothesis concerning the
dynamic balance of fresh water and salt water in a coastal aquifer:
U.S. Geological Survey Water-Supply Paper 1613-C, p. 1-12)."
Saltwater intrusion occurs when large amounts of saltwater move into an
aquifer's freshwater supply and create brackish water. Generally, it
occurs when the water level of an aquifer is lowered and freshwater is
being withdrawn at faster rate than at which it is being replenished.
The rate at which saltwater intrusion occurs depends upon the water
level of the aquifer and the rates of replenishment and withdrawal.
Saltwater Intrusion in a
A certain amount of mixing between freshwater and saltwater in a
coastal aquifer is natural. This happens in an area know as a zone of
dispersion. The overall flow of freshwater in the aquifer moves toward
the ocean. This movement keeps the saltwater from intruding.
Saltwater intrusion has occurred in the Biscayne
aquifer for a variety of reasons including the drainage of freshwater
by canals, the seepage of saltwater into the aquifer by canals, the
over-pumping of freshwater by wells and lowering of the water table by
drought. Intrusion is a problem because it makes the groundwater
undrinkable for people.
To Watch Saltwater Intrusion
Saltwater Intrusion Animation Page
1). U.S. Geological Survey. Water-Resources Investigations Report
Delineation of Saltwater Intrusion in the Biscayne Aquifer,
Eastern Dade County, Florida, 1995. By Roy S. Sonenshein. http://www.sflorida.er.usgs.gov/online_reports/wri964285/
2). U.S. Geological Survey. Ground-water flow patterns and the
zone of dispersion in an idealized, homogeneous coastal aquifer.
By Paul Barlow. http://water.usgs.gov/ogw/gwrp/saltwater/salt.html#fig2
Circular 1262. Ground Water in Freshwater-Saltwater
Environments of the Atlantic Coast. By Paul M. Barlow.