Describe saltwater incursion. What methods are used to counteract ...

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Describe saltwater incursion. What methods are used to counteract saltwater incursion? What will be an ideal response?

Question 2

How do septic systems work to make sewage safe for use as water? What will be an ideal response?

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Answer to Question 1

The excessive pumping of groundwater in coastal areas results in saltwater incursion. When freshwater
is pumped from an aquifer that is in contact with the ocean, the seawater is pulled into the aquifer. The
fresh groundwater is less dense than the seawater and forms a lens-shaped body above the underlying
saltwater. A deep cone of depression may form in the fresh groundwater, and the saltwater may form a
cone of ascension to fill the pore spaces that formerly contained freshwater. The wells remain
contaminated with saltwater until freshwater recharge refills the aquifer.

Answer to Question 2

Septic tanks dispose of sewage in many areas. A septic tank slowly releases sewage into the ground,
where it is decomposed by oxidation and microorganisms and filtered by the sediment as it percolates
through the zone of aeration. By the time the sewage has reached the zone of saturation, it has been
cleansed of any impurities and is safe to use if the water table is not close to the surface.