What causes saline intrusion?
As sea levels rise, their saline water will be able to overcome natural barriers to move into low lying areas now dominated by freshwater. Rising sea levels will also push seawater into coastal fresh water aquifers. While this impact may not be noticed on the surface it could affect groundwater that seeps into estuaries. Figure 1. Saltwater-freshwater interface in: (a) an unconfined (hypothetical) coastal aquifer; and (b) the same aquifer under a sea-level rise scenario. In the sea-level rise scenario, abstraction from the coastal boreholes would be reduced or stopped altogether due to the intrusion of saline water into the aquifer.
