New York Science Journal, http://www.sciencepub.org , ISSN 1554-0200 20 Electrical Resistivity Survey in Daibega Plain, Southwest Erbil City – Iraqi Kurdistan Region Fadhil A. Ghaib Department of Geology, Salahaddin University in Erbil Iraqi Kurdistan Region f_ghaib@yahoo.com Abstract: Vertical Electrical Soundings (VES) with Schlumberger configuration were conducted in Daibega area (Southwest Erbil City – Iraqi Kurdistan Region). The area is a plain occupying a broad syncline. Obtaining some aquifer parameters, locating favorable groundwater zones, water depth and water types in the area were the aims of this study. For those purposes 26 VES’s with 800m current electrode separation were conducted within the watershed area. Interpreted VES data were correlated with some existed borehole columns. A present iso-salinity map of the area was used to obtain the resistivity values of the aquifer water and correlated with resistivity values of aquifer rocks. An iso- depth map for the estimated water table also was constructed. Based on VES interpretations integrated with the previously present data the study showed mostly poor zones of fresh waters. Depth of water table is in the range of 50m in the central parts of the area increasing towards north and south reaching about 80 m. [New York Science Journal. 2008;1(3):20-37]. (ISSN: 1554-0200). Keywords: Electrical Resistivity Survey; Daibega Plain; Southwest Erbil City; Iraqi; Kurdistan 1. Introduction The rectangle-shape of the northwestern half of the Daibega plain which is tested electrically in this study is situated some 50km southwest of Erbil City covering an area of about 450km 2 (Fig. 1). Other than rain in winter and spring seasons no surface water supply sources or water projects are present for most of the villages within the plain. The only source is the underground water. A lot of hand-dug and some deep wells have been drilled. Many of them are not suitable for human drinking because of salinity of their water. Salts are mainly because of the gypsum which exists as one of the lithological units of the Lower Fars Formation. The resistivity method involves measuring the electrical resistivity of earth materials, by introducing an electrical current into the ground and monitoring its developed potential field. In most earth materials, electricity is conducted electrolytically by the interstitial fluid. The resistivity is controlled mostly by porosity, water content and water quality than by the resistivities of the matrix (Ayer, 1989). The main target is the identification of horizontal and vertical variations in lithology (including water type in pores), which lead to clarify the structural picture of the subsurface. The present data was originally used for the assessment of the groundwater situation in the area under study by the Swedish Qendeel NGO, Erbil. This work was carried out by their permission. 2-Geology The area according to Numan, 1997 is located within the Zone of "Suspended Basins’ of the Quasiplatform forland. This area is equivalent to the so-called "Foot Hills Zone” which belongs to the “Folded Zone" in former literature of the tectonics of Iraq (Buday and Jassim, 1987) (the upper box in Figure-1). This zone is characterized by relatively long double plunging anticlines with broad synclines in-between. They mostly trend in the NW-SE direction. The Daibega plain is a syncline between the two anticlines Avana in the northeast and Qerechugh in the southwest. In the north of the plain a third anticline (Gwair) is present in an en- echelon position (Figs. 1 and 2). The oldest rock formations present in the area are those which belong to Oligocene age. These rock formations collectively form the core of the Qerechugh Anticline (Fig. 1). This figure also shows a cross section across the plain. Table 1 shows a summary for all exposed formations in the area (cited in Al-Sudany, 2003).