Aquifer boundaries explored by geoelectrical measurements in the Red Sea coastal plain of Jazan area, Southwest Saudi Arabia

Abstract

Geoelectrical measurements using the vertical electrical sounding (VES) method were conducted on the Eastern Red Sea coast in Jazan area, Southwest Saudi Arabia. The objectives of the study were (1) to map the Quaternary sediments in areas where little is known about the subsurface geology and to infer shallow geological structure, and (2) to identify formations that may present fresh aquifer waters, and subsequently to estimate the relationship between groundwater resources and geological structures. Data collected at 9 locations were interpreted first with curve-matching techniques, using theoretically calculated master curves. The initial earth models were double checked and reinterpreted using a one-dimensional inversion program in order to obtain final earth models. Resistivity measurements show four zones with different resistivity values, corresponding to four different bearing formations: (1) A resistive surface layer at the top; (2) A basalt flow layer in the northern parts; (3) Strata saturated with fresh to brackish groundwater; and (4) A water-bearing formation containing Red Sea saltwater. Key words: Salt-water/fresh-water, geoelectrical measurements, Red Sea coastal plain,Saudi Arabia.