Ecology Saltwater Intrusion and Salinization

Ecology Saltwater Intrusion and Salinization Approximately two thirds of the world's population lives within 400 km of an ocean shoreline. The majority of these coastal regions depend on groundwater as their main source of fresh water. As the world's population continues to increase, fresh water supplies are continually being depleted, which brings with it issues like saltwater intrusion. This increases the importance of groundwater monitoring, management, and conservation (Pump/Recharge Rate Affects Saltwater Intrusion, 2010).

Saltwater intrusion is the provoked flow of seawater into freshwater aquifers principally caused by groundwater development near the coast. Wherever groundwater is being pumped from aquifers that are in hydraulic connection with the sea, induced gradients are causing the migration of salt water from the sea toward a well, making freshwater wells not viable. Due to the reality that fresh water is less dense than salt water it floats on top. The border between salt water and fresh water is not distinct.

The region of dispersion is found to be saline because of the mixing of salt water with fresh water. Under normal circumstances, fresh water moves from inland aquifers and recharge areas into coastal discharge areas. Generally, groundwater moves from areas with higher groundwater levels to areas with lower groundwater levels. This ordinary movement of fresh water towards the sea avers salt water from getting into freshwater coastal aquifers (Pump/Recharge Rate Affects Saltwater Intrusion, 2010).

Saltwater intrusion and salinization occurs when there is an enhancement of chloride ion concentrations in freshwater aquifers. This occurs mainly along coastlines, although there have been reports of salinization occurring inland. Saltwater intrusion has several causes, a number of which are natural and some which are a result of by human actions. Once saltwater intrusion has happened, it is almost impossible to turn around, which makes it a significant threat to freshwater resources.

Mitigation strategies are put into place in order to slow or halt the rate that saltwater intrusion occurs (Ryan, 2008). One of the natural reasons for saltwater intrusion comes from storm surges that are caused by hurricanes and other tropical storms. In these cases, tidal flushing is recognized to remove some of the established salinity in the freshwater marshes before substantial damage happens.

In areas that are not close to tidal flushing along with areas where rainfall does not flush the salt water from the water table, there is substantial damage that occurs to the freshwater systems. Human made saltwater intrusion occurs in a number of different ways. One way is by dredging canals in coastal zones that allow saltwater to move even farther inland than it had been able to previously (Ryan, 2008).

One of the most remarkable forms of saltwater intrusion happens in coastal areas that are reliant upon groundwater for their potable water and irrigation needs. The most widespread situation involves the over pumping of the freshwater which reduces the chief difference at the saltwater-freshwater edge and induces the flow of saltwater into the freshwater system. This is often aggravated by insufficient renewal to the freshwater aquifer, which often occurs in times of drought (Ryan, 2008).

Unfortunately saltwater intrusion can't be stopped, but the rate at which it occurs needs to be slowed. A management plan for saltwater intrusion needs to involve a number of different approaches. In areas where salinization is caused by storm surge, it is thought that coastal barriers could be built in order to prevent or slow the storm surge. Where saltwater has been introduced because of storm surge, some manner of opening the barriers would be necessary in order to allow the saltwater to be washed out of the freshwater system.

This would involve a substantial engineering requirement. Opponents to this approach argue that engineering a natural process would end up doing more harm because of the impact the structures would have on natural systems. Conversely, the loss of wetland habitat influences many things including tourism in coastal area (Ryan, 2008). In areas that are burdened with saltwater intrusion because of over pumping of the overlying freshwater aquifers, the management solution should involve cooperation from multiple levels.

The main dilemma of pumping groundwater at a pace that is not sustainable must be looked at. On the other hand, the impact of the saltwater intrusion must be calculated. This is usually done by approximating how many wells have previously been impacted and what the projection is for potential impacts given the current pumping rates. It is thought that the cost of reducing groundwater withdrawals is more than the cost of re-establishing wells that have been affected by saltwater intrusion (Ryan, 2008).

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