Saltwater Intruding Into Atlantic Coastal Aquifers
More than 65 million people live in Atlantic coastal communities and withdraw about 7.7 billion gallons each day from underground aquifers for public supplies, agriculture and industry. In many Atlantic coast communities, groundwater is the primary or sole source of drinking water supply.
To address the critical role of groundwater in sustaining coastal populations, economies, and ecosystems, the U.S. Geological Survey (USGS) has published a report that describes groundwater conditions in freshwater and saltwater environments along the Atlantic coast.
Groundwater supplies are vulnerable to overuse and contamination, and the proximity of coastal aquifers to saltwater creates unique issues of groundwater sustainability in coastal regions.
The USGS report identifies several scientific challenges and opportunities related to groundwater conditions along the Atlantic coast.
“New monitoring and research efforts will be needed to characterize the occurrence and movement of saline groundwater in different types of coastal terrains and to better understand linkages between groundwater discharge, groundwater quality and the health of coastal ecosystems,” says USGS hydrologist Paul Barlow, author of the study.
The movement of saline water into freshwater aquifers, called saltwater intrusion, is usually caused by groundwater pumping from coastal wells.
In extreme cases, saltwater contamination has led to the abandonment of supply wells in several communities along the Atlantic coast, and is a continuing threat in many areas. The report describes multifaceted strategies for managing saltwater intrusion in coastal Georgia, and in Florida’s Biscayne Bay.
Barlow covers the role of the Chesapeake Bay impact crater on Virginia’s inland saltwater wedge, the effects of paleochannels on saltwater intrusion along the Georgia and Carolina coasts, and the role of fractures and other structural anomalies on saline water movement in northeastern Florida.
“Many states and local communities are taking actions to manage and prevent saltwater intrusion to ensure a sustainable source of groundwater for the future,” said Barlow.
Innovative management approaches such as aquifer storage and recovery systems, desalination systems, and blending of waters of different quality, are being implemented to manage saltwater intrusion, and several monitoring networks are in place to document the location and movement of saltwater in freshwater aquifers.
The USGS report also addresses the role of groundwater in delivering contaminants to coastal waters. This has become an area of growing concern because the discharge of excess nutrients, particularly nitrogen, can severely impair coastal ecosystems.
As coastal populations expand into undeveloped areas, it is likely that new patterns of saltwater occurrence and intrusion will be identified that will require scientific analysis and monitoring, Barlow says.
Provided by theEnvironmental News Service.