Delineation of seawater intrusion in the Yanbu industrial area, northwest Saudi Arabia, using geoelectric resistivity sounding survey

Eleven Schlumberger array vertical electrical soundings were done at specified places in the Yanbu industrial sector, northwest Saudi Arabia, to identify possible seawater intrusion that may influence the shallow groundwater aquifer along the city's coastline zone. The variations of the resistivity values indicate the subdivision of the study area into two zones. These zones are characterized by different VES curve types; the Q -type and the Htype which dominate in the western and the eastern zones, respectively. VES data show three geoelectric resistivity layers. The first layer is an inhomogeneous layer with a wide range of resistivities correlated to Quaternary sediments (ranges from gravel, and sand to silt and clay) of variable lithology and water content. The resistivity of the second layer indicates abundant clay with a local change in the lithology to become gravel and coarse sand. The third layer shows a sudden and sharp variation of the resistivities; indicating a possible fault affected the coastal plain. This faulting system uplifts the basement, which may operate as an impermeable or sealing wall to prevent seawater from entering the shallow groundwater aquifer in the west. Most seawater intrusion in the studied area is regulated by faulting and lateral lithologic changes.