The nature and causes of saline water intrusion geophysical investigation techniques, and groundwater quality assessment and mapping 3

Saline water intrusion is a hydrogeological process in which seawater or highly mineralized water encroaches into freshwater aquifers, commonly occurring in coastal regions due to factors such as excessive groundwater abstraction, sea-level rise, reduced recharge, and geological conditions that facilitate hydraulic connectivity. The nature of this phenomenon is governed by density differences between saline and freshwater, leading to a dynamic interface that shifts inland when equilibrium is disturbed. To investigate and monitor saline intrusion, geophysical techniques such as electrical resistivity tomography (ERT), electromagnetic (EM) surveys, seismic methods, and induced polarization are widely used, as they enable non-invasive mapping of subsurface salinity variations and aquifer structures. Groundwater quality assessment involves analyzing physical and chemical parameters, including total dissolved solids (TDS), electrical conductivity (EC), pH, and ion concentrations, to determine suitability for domestic, agricultural, and industrial uses. These data are integrated using geographic information systems (GIS) and spatial modeling techniques to produce groundwater quality maps, which help visualize contamination levels, identify vulnerable zones, and guide sustainable water resource management and mitigation strategies.