Saline-Water Intrusion Management

Abstract

Saline-water intrusion is the induced flow of saline or brackish water into freshwater aquifers. In coastal areas, horizontal saline-water intrusion involves the landward migration of the roughly wedge-shaped interface between saline and fresh groundwater. Vertical saline-water intrusion (referred to as up-coning) is the upward migration of more saline water into freshwater aquifers or aquifer zones. Horizontal and vertical saline-water intrusion are commonly caused by excessive groundwater extractions lowering the head (pressure) in a freshwater-containing area of an aquifer, inducing the flow of the saline water toward the pumped area. Increases in groundwater salinity (i.e., salinization) in coastal areas may have causes other than vertical and horizontal saline-water intrusion. Therefore, it is important to first ascertain the actual cause(s) of observed salinity increases. Saline-water intrusion can be managed using three basic strategies, reduce or eliminate the causes of intrusion (i.e., restore the local water balance), creating a hydraulic barrier at or near the freshwater/saline-water interface, or construction of a physical barrier.