saltvattenakviferer

Saltvattenakviferer are groundwater reservoirs in which the pore water is saline or brackish, commonly found in coastal regions. They form where permeable sediments such as sands or carbonates lie near shore and are overlain by less permeable layers that slow vertical flow. In many coastal aquifers, freshwater from rainfall sits above denser seawater, creating a persistent salinity gradient. The interface between freshwater and seawater is often described by the Ghyben-Hertzberg principle, which crudely links the depth of the saltwater wedge below sea level to the height of the freshwater column above it (approximately 40:1).

Natural salinity in these systems can arise from residual seawater from past marine incursions and from brines associated with evaporite deposits; however, human activity commonly drives salinization through groundwater extraction and sea-level rise. Intensive pumping near coastlines lowers the freshwater hydraulic head, allowing seawater to move landward and contaminate wells. Climate change, drought and land subsidence can worsen saltwater intrusion and degrade potable-water supplies.

Management and protection focus on preserving freshwater in coastal aquifers and limiting intrusion. Strategies include reducing coastal pumping, artificial recharge to boost freshwater head, construction of hydraulic barriers, managed aquifer recharge, and, where needed, treatment or blending of saline groundwater for non-potable uses. Desalination and careful land-use planning also play roles in sustaining coastal water resources.

Saltvattenakviferer are thus a key component of coastal hydrogeology, offering potential as a water resource when properly managed and treated.