The Modeling of Salt Water Intrusion

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The Modeling of Salt Water Intrusion

What is Salt Water Intrusion?

Salt water intrusion, or encroachment, is defined by Freeze and Cherry (1979) as the migration of salt water into fresh water aquifers under the influence of groundwater development. Salt water intrusion becomes a problem in coastal areas where fresh water aquifers are hydraulically connected with seawater. When large amounts of fresh water are withdrawn from these aquifers, hydraulic gradients encourage the flow of seawater toward the pumped well or wells. Salt water intrusion is a problem that affects coastal areas around the world. Groundwater Problems in Coastal Areas (Custodio, 1987) is an excellent reference for more information on global salt water intrusion problems, while Atkinson (1986) details salt water intrusion problems for the coastal areas of the United States.

Why is it a Problem?

The encroachment of salt water into fresh water supplies has become cause for concern within the last century as populations in coastal areas have risen sharply and placed greater demands on fresh groundwater reserves. Salt water intrusion causes many problems in these areas, perhaps the most severe being the limitation of potable drinking water. Drinking water standards established by the EPA in 1962 require that drinking water contain no more than 500 mg/L of total suspended solids (TSS), a common measure of salinity (Atkinson, 1986). Seawater contains approximately 30000 mg/L of TSS. Therefore, it is evident that even a small amount of seawater can cause drinking water problems when mixed with fresh water reserves. Also, salinity in irrigation water can be detrimental to agriculture, reducing yields and killing crops with low tolerances to salt. In some...

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...t Modeling of the Flow Through Porous Media". OWRT-C-4026(9006)(4). Office of Water Resources and Technology, U.S. Dept. of the Interior. Washington, DC. March, 1975.

Christensen, B.A., "Mathematical Methods for Analysis of Fresh Water Lenses in the Coastal Zones of the Floridian Aquifer". OWRT-A-032-FLA(1). Office of Water Research and Technology. U.S. Dept. of the Interior. Washington, DC.

Custodio, E., and Llamas, M.R. Hidrologia Subterranea. Ed. Omega, Barcelona. 1976.

Custodio, E. (prepared by). Groundwater Problems in Coastal Areas. A contribution to the International Hydrological Programme. 1987.

Freeze, R. A. and J. A. Cherry. Groundwater. Prentice Hall, Inc. 1979.

Jenkins, S. R. and R. K. Moore. "Effect of Saltwater Intrusion on Soil Erodibility of Alabama Marshlands". Water Resources Research Institute, Auburn University, Auburn, Al. 1984.
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