Application of Vertical Electrical Sounding for Delineation of Sea Water Intrusion into the Freshwater Aquifer of Southern Governorates of Gaza Strip, Palestine.

Vertical Electrical Sounding (VES) proved to be an important tool for mapping the freshwater-saltwater interface. Seawater intrusion is serious problem especially in coastal areas. 14 Vertical electrical soundings with Schlumberger array were carried out (perpendicular to the coast) in southern part of the coastal aquifer in Gaza Strip (Khan Younis and Rafah Governorates) to study the subsurface geologic formation and delineation of seawater intrusion into freshwater aquifer. Lithology and hydrochemistry data from 12 bore holes were used to integrate the results. The results reveals that 50% of the total sounding are interpreted of 3 layer modes, while the other 50% are of 4 layers model. Interpreted 2D geoelectrical models (in two cross sections parallel to the coast line) showed that seawater intrusion with electrical resistivity less than 2Ωm is dominant along the section parallel to coast line at 400m east of it and for shallow depths (3-10m depth), while in the other section (1000m) east of the coast line seawater intrusion is detected in some places while the other parts still have brackish/fresh groundwater with resistivity more than 10Ωm at different depths (26-50m). [ABSTRACT FROM AUTHOR]