Introduction:
Saltwater
intrusion represents the process by which sea water infiltrates coastal
groundwater systems, thus combining with the local fresh water supply. Groundwater
is stored in the pores and fractures of rock within the surface, and the rock
structures containing groundwater are termed as aquifers. Aquifers are
naturally replenished by way of precipitation (rain, snow) that penetrates into
the ground and eventually reaches to the water table.
The water table
is simply the boundary between the upper part of the ground that is only
partially soaked with water (unsaturated zone) and the lower part where all the
pore spaces and fractures are fully soaked with water. The level of the water
table at any point is often referred to as the “hydraulic head.”
Salt
water intrusion into coastal aquifers is brought on by two mechanisms:
• Lateral
encroachment from the sea due to excessive water distributions from coastal
aquifers,.
• Upward
activity from deeper saline areas due to upconing near coastal
discharge/pumping water wells.
How to Prevent Water Intrusion
People in the
United States sink have been relying on groundwater aquifers as a source of
fresh water for a growing population for over a century. They made effort to
prevent continuous salt water intrusion by developing a sequence of injection
wells.
These injection
wells were tactically placed with the idea that if they included fresh water
into the aquifers at a given place, then they might be able to develop barriers
to prevent further intrusion of the salt water. These limitations proved to
only be partly efficient, and only prevented further salt water encroachment
into the fresh water aquifer.
Controlling Saltwater Intrusion
The key to manage salt water intrusion is to
maintain the appropriate balance between water being pumped from an aquifer and
the amount of water re-charging it.
Constant monitoring of the salt-water interface is necessary in
determining the proper management technique.
In the past, many areas that came across a salt water intrusion problem
simply set up new production wells. This
only complicated the issue.
