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Biscayne Aquifer - Saltwater Intrusion
Renewal & Removal of Groundwater - Page 1
Renewal & Removal of Groundwater page 2
 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 Generally, it occurs when the water level of an aquifer is lowered and freshwater is being withdrawn at faster rate than at which it is being replenished.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
Coastal Aquifer
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
Animation
Saltwater Intrusion Animation Page
Sources:
1). U.S. Geological Survey. Water-Resources Investigations Report
96-4285.
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.
http://water.usgs.gov/pubs/circ/2003/circ1262/