Are the lower subaquifers of the Mediterranean coastal aquifer of Israel blocked to seawater intrusion? Results of a TDEM (time domain electromagnetic) study †

Kafri, U. and Goldman, M. Are the lower subaquifers of the Mediterranean coastal aquifer of Israel blocked to seawater intrusion? Results of a TDEM (time domain electromagnetic) study. Isr. J. Earth Sci. 55: xx-xx. The TDEM (time domain electromagnetic) method was employed to delineate a low resistivity seawater intrusion into the multiple aquifer system of the Mediterranean coastal aquifer of Israel. The upper (A, B) subaquifers of the aquifer have been known for a long time to be intruded by seawater along the entire coastal plain. It was sug- gested in the past and supported by sparse hydrogeological information that the lower (C, D) subaquifers are blocked to the sea and thus might escape seawater intrusion. The results of the survey, in conjunction with existing borehole information, al- lowed delineating large areas along the central and southern coastal aquifer, where the lower subaquifers solely occupy relatively fresh water (below 1000 mg/l Cl) close to the seashore. The largest of these areas is an approximately 20 km strip between north Ashdod and Bat Yam. According to the low TDEM resistivities obtained at appropri- ate depths, the lower subaquifers at other areas seem to be locally blocked to the sea or vice versa intruded by seawater.