AQUIFERS DELINEATION USING VERTICAL ELECTRICAL SOUNDING IN SOUTH AND SOUTHWEST OF SAMAWA CITY, SOUTHERN IRAQ

Abstract

This study includes application of (VES) Vertical Electrical Sounding for delineation of aquifers in the area located south and southwest of Samawa City, southern Iraq. The VES was carried out by using Schlumberger array in the 16 sounding points distributed along three profiles trending NW – SE, except one point that is not located within any profile. The field curves of apparent resistivity are interpreted by the application of forward calculation and inverse modeling. The results of the inverse modeling are used to construct three geo-electrical sections along electrical profiles, and then converted to geological sections by including the lithological well sections and all available geological and hydro-geological information. The results indicate the presence of three aquifers. The first is the Euphrates aquifer which is located at depths ranging between 1 and 7 m. This aquifer overlaps with the Ghar aquifer in the southeast area, and thus forming one hydro-geological unit. The thickness of this aquifer varies from 8 to 30 m. The second is the Ghar aquifer which appears at depths (1 – 3) m. The thickness of this aquifer ranges between 12 and 40 m. The third is Dammam aquifer, which occurs below the Euphrates aquifer in the north and southeast of the Al-Emaed spring. It also occurs below the Euphrates and the Ghar aquifers in the southeast end of the studied area; its depths ranges between 13 and 43 m, in most locations, but to the south and southwest of Al-Emaed spring, near the ground surface. Its thickness ranges between 100 and 120 m, and it splits into two parts in the area located north and southeast of Al-Emaed spring. The lower part is characterized by increased fractures in comparison with the upper part. The presence of hydraulic connection between these aquifers is observed and this agrees with previous studies.