Geoelectrical investigation for characterizing the hydrogeological conditions in semi-arid region in Khanasser valley, Syria

In the Khanasser valley, considered as a semi-arid region in Syria, the shallow ground-water presents electrical conductivities ranging from 0.1 to 20 mS/cm. In order to study the hydrogeological conditions of such region, a good knowledge is required of the geometry of the aquifer at depth. Ninety-six vertical electrical soundings (VES) using the Schlumberger array were carried out in the study area. The established iso-apparent resistivity maps for different AB/2 spacings indicate the presence of two different geological structures; characterized by very conductive zones of a resistivity < 4 Omega m related to the intrusion of salt water in Quaternary and Paleogene deposits. Resistive zones have been signaled in Jebel Al Hass in the west and Jebel Shbith in the east, characterized by a resistivity exceeding 300 Omega m, due to the presence of basalt formation of upper Miocene age. Thickness of the Quaternary, Paleogene and their electrical characteristics have been precisely determined. The top of Maestrichtian and its electrical characteristics have been also well established. Quaternary paleosabkhas were delineated through the studying of three longitudinal profiles along the valley itself (LP1, LP2, and LP3). Fractured zones and tectonic features of the subsurface of Khanasser valley have been very well determined through the interpretation of VES of the profiles LP1, LP2, and LP3 using the Pichgin and Habibullaev method. The geoelectrical approach was successfully applied in the study area and can be therefore easily practiced in similar environments. (c) 2006 Elsevier Ltd. All rights reserved.