Salt Water Intrusion
Salt Water Intrusion and Salination By: Ryan Tallman University of Phoenix 2009 In this modern world we are faced with many different issues. Sometimes we forget that the majority of our earth is covered in oceans and freshwater. Almost two thirds of the world’s population lives within 250 miles of an ocean coastline. One of the many issues we are facing in our waters is saltwater intrusion and salinization. Saltwater intrusion and salinization is defined as the increase of chloride ion concentrations in freshwater aquifers or more simply put the movement of saline water into freshwater aquifers.
When fresh water is withdrawn at a faster rate than it can be replenished, as a result the water table is drawn down. This also reduces the hydrostatic pressure. When this happens near an ocean coastal area, salt water from the ocean is pulled into the aquifer resulting in saltwater intrusion. This occurs more often along our coastlines, though there have been cases of this occurrence inland. Saltwater intrusion can be caused by many different actions, some natural and some that are caused by human activities.
The natural causes of saltwater intrusion are seen as storm surges that are caused by hurricanes and other tropical storms. This was seen in 2005 when Hurricanes Katrina and Rita hit land along the Gulf Coast of the United States. Tidal flushing removed some of the introduced salinity in the freshwater marshes before substantial damage was done. However in the areas where tidal flushing was not an option and where precipitation was not able to flush the salt water from the water table, there was considerable damage to the freshwater systems.
Some human causes result from human activities like construction of navigation channels or oil field canals. These channels and canals provide conduits for salt water from the Gulf of Mexico to reach deep into inland marshes. Saltwater intrusion can be detrimental to these marshes because water with high salt concentrations can severely affect vegetation in the marsh. When water that is high in saline enters an area that normally has little to no saline, most or the entirety of the plant life native to that area will be destroyed.
Because plant root systems are essential in holding the marsh soil together, the loss of that plant life will eventually lead to rapid erosion. You will start seeing that what was once a wetland will soon become open water. Once saltwater intrusion has occurred, it is almost impossible to reverse, making this a significant threat to freshwater resources. Mitigation strategies have been implicated to slow down or stop the rate of saltwater intrusion. These processes can be costly but they are necessary to protect our resources from further damage.
The increase of the use of groundwater has caused the salt-water to move inland and closer to the ground surface along much of the Atlantic Coast of the United States, as well as Southern California. In the past, many communities in these areas who came across saltwater intrusion problems set up new wells further inland. However this seemed to only further complicate the issue. Since then, efforts to maintain groundwater levels by using river water to recharge the groundwater tables have been successfully implemented. Some communities are setting up committees and holding conferences to discuss this threat.
These conferences are designed to bring together scientists, engineers, water resource managers, and policy makers who are actively involved in or have been affected by salt water intrusion, management of coastal aquifers, and submarine groundwater discharge. This includes those studying the marine environment as well as those from the terrestrial side. Participants from academic fields, private consulting firms, local, state, and national government agencies will interact in an informal and relaxed environment to summarize and review state-of-the-art methods for investigating salt water intrusion.
Like before mentioned in the paper the challenges we face most are the man-made issues as well as the natural causes that are not prevented. We have to attend these meeting and if there are not any committees in your town and this is a problem then take it to you city council and start a committee. There need to be precaution taken when doing construction in sensitive areas and the more preventative actions that are taken now will protect us more in the future.