| الملخص | For the purpose of determination the table of the groundwater in an area, which is located at a distance of about 6 km southwest Karbala City, Vertical Electrical Sounding survey has been carried out. The survey, which occupies an area of about 55 km2, has been covered by grid of forty measuring stations distributed on five N – S trending profiles. The interval between these stations is almost 2 km. The maximum distance between the current electrodes is 466 m. New software IPI2Win has been used for interpretation of the filed data, and a model of five layer case is adopted. The variation of shapes of the sounding curves are almost related to variation in lithology (Vertical or lateral) or variation in layer thickness or variations in some physical properties controlling rock resistivities, and the last one has the main role throughout the study area. Nine resistivity and pseudo cross-sections are displayed in E – W direction. The depth of investigation is (14 – 157) m with an average of 58 m. The main groundwater aquifer lies at a depth ranging between (20 – 82) m, and it is almost about 45 m from the ground surface. Moreover, it is believed that the main aquifer is of unconfined type, since there is no sharp dropping in the resistivity. This suggests a hydraulic connection between the main aquifer and the uppermost aquifer (Dibdibba-Injana aquifer). In addition a hydraulic connection is observed between the main aquifer and the lower most aquifer in some stations that may refer to that the lowermost aquifer is of semi-unconfined type. However, a relatively less extended aquifer that may occupy Dibdibba and the upper part of Injana Formations has been noticed in many stations. Finally, after studying the results, four boreholes of total depth 400 m are suggested for drilling to calibrate the proposed geophysical model and to make the necessary modifications for this model then calculating the final model that could be applied on the study area and surrounding. However, the results of drilling are important in determination the accuracy of the calculating thicknesses of the friable sand that may be of economic interest as sand quarries. | |
