Geoelectric monitoring of saline water intrusion in dibdibba aquifer at Zubair-Safwan area Southern Iraq

Abstract EN

78 Vertical Electrical Sounding measuring points using Schlumberger array were carried out within Basrah Governorate at Zubair-Safwan area, southern Iraq, in order to determine the number of the underlying layers, depths and their thicknesses, boot to groundwater table and its influence by the saline water intrusion which coming from Khur Al-Zubair coastal or even deep layers towards Dibdibba Aquifer.

Qualitative interpretation was applied using the type study of the electrical field curves for these VES's to get preliminary picture for lateral and vertical variations in underlying layers resistivities and lithology.

Moreover, quantitative interpretation was carried out using IPI2win program.

Five space sections and five geoelectrical sections were then drawn along five profiles for each one.

The interpretation of these sections clarified that there are three underlying groundwater bearing beds.

Thicknesses and resistivities of these beds were calculated depending on the assistance of the drilled observation wells.

It is noticed that there is a decreasing in the apparent resistivity values with depth especially at the groundwater bearing intervals.

This is because of the salinity increases occurred in groundwater at these intervals.

Due to unprogrammed groundwater pumping, high concentration of salinity in the lower part of Dibdibba aquifer might be altering the upper part of it and changing it from freshbrackish to saline.

Large reduction in the apparent resistivity values is also observed at the eastern parts of the study area near Khur Al-Zubair boundaries which indicates high electrical conductivity values ; however, this is led to the increasing of the saline water that probably comes from the sea.

This fact is certainly approved by the interpretation of the extracted iso-resistivity contour map and an irregular front line separates between low (saline) and high (brackish to fresh) resistivities can be recognized along this map.