تكامل تقنيات المقاومية الكهربائية أحادية و ثنائية البعد في تحديد سمك و امتداد الخزان الجوفي الرئيسي في منطقة الرهيمة، محافظة النجف، وسط العراق

Abstract EN

An electrical survey is carried out at Al-Rehaemia area within Bahr Al-Najaf Depression by applying Vertical Electrical Sounding (VES) and 2D Electrical Resistivity Tomography (ERT) techniques to determine the thickness and extension of the main aquifer used for irrigation purposes.

A total of ten VESs are measured using liner Schlumberger array configuration with maximum AB/2 = 400 m along two traverses of 4km length, each traverse has five VES points of 1km spacing interval.

The ERT survey is conducted along three parallel traverses, 400 m long each, using Wenner-Schlumberger array.

The electrode separation for the data measurements is 10 m, whereas the distance between the traverses is 15 m.

The VESs data are processed and interpreted using IPI2win software, whereas RES2DINV software is used for the 2D resistivity data.

The penetration depth of the VES is about 350m, and it is closed to 70m for the 2D electrical resistivity sections.

The results show the presence of four geoelectrical zones and the resistivity range is 2 – 80 ohm.m.

The first zone is 1 – 4.5 m thick, characterized by relatively low resistivity and represents top soil.

The second zone is 9 – 152 m.

thick impermeable layer of marl and recrystallized marly limestone of the upper member of the Dammam Formation, and it is characterized by moderate values of resistivity.

The third zone is 125 – 250 m thick carbonate rocks of the lower member of the Dammam Formation and represents the main aquifer in the area.

The fourth zone is detected by VES only as an impermeable layer (Aquiclude) which consists of marl and evaporates and represents the Rus Formation.

The results show that the depth of the groundwater level is about 23 m.

They also showed a good agreement with the 2D electrical resistivity technique in determining the subsurface lithology of the area and the level of groundwater in the main aquifer as indicated by the geological data available.