## 5 Results and Discussion
### 3D Illustration and Interpretation of Electrical Resistivity Tomography  
The goal of creating a three-dimensional ERT model for the study area was to characterize the vertical and the horizontal distributions of the resistivity values of the subsurface lithological units beneath the surface. Geosoft Oasis Montaj software version 8.3 was used to create a 3D VOXEL model using the outcomes of the inverted 2D ERT profiles; specifically, profiles 1-11 west of the Osirion site and excluded the other profiles (P12-P14). The statistical kriging algorithm was primarily employed in this procedure for 3D meshing  
Figure 6: Interpreted 2D inverted resistivity model of profiles 5–8. According to the resistivity values, four difference geoelectric zones were recognized. These zones are: (1) wadi deposits, which are mainly composed of gravels, sands, and silts; (2) medium sand deposits; (3) muddy sand deposits; and (4) clay deposits. to generate a 3D voxel network model, which involved combining the inverted results of 2D ERT files into a single file (Figure 9). The required data must have the following three data fields: X, Y, and Z, where X and Y are the actual universal transverse mercator (UTM) coordinates in meters; Z is the depth in meters; and the data field is the resistivity in ohm.m. Figure 7: Interpreted 2D inverted resistivity model of profiles 9–12. According to the resistivity values, four difference geoelectric zones were recognized. These zones are: (1) wadi deposits, which are mainly composed of gravels, sands, and silts; (2) medium sand deposits; (3) muddy sand deposits; and (4) clay deposits. In order to clearly portray the 3D illustration of the electrical resistivity distributions of the geoelectric zones that characterize the site at various depths from the ground surface (Figure 10), the 3D voxel was sliced into 13 horizontal slices. To keep the length of this paper, only six slices at depths of 0.51, 3.8, 6.53, 9.85, 16.16, and 21.49 m were used to describe the horizontal and vertical distributions of the resistivity values (Figure 11). Figure 8: Interpreted 2D inverted resistivity model of profiles 13–14. According to the resistivity values, four difference geoelectric zones were recognized. These zones are: (1) wadi deposits, which are mainly composed of gravels, sands, and silts; (2) medium sand deposits; (3) muddy sand deposits; and (4) clay deposits. Figure 9: A 3D voxel model of the inverted 2D electrical resistivity profiles (P1 to P11) using Geosoft Oasis Montaj Software version 8.3 that was sliced to horizontal sections at different depths to explain the vertical and horizontal changes in the resistivity values within the investigated site. The first geoelectrical zone appears progressively near the ground surface at a depth of about 0.51 m in the northern and north-eastern directions of the study site, and decreases in the western and southern directions. With increasing the depth, this zone begins to gradually disappear until a depth of about 6.53 m; and then, begins to increase again until it reaches its highest appearance at a depth of 21.49 m, which means that this zone was invaded by active water current suspended with other material. These currents eroded this zone, replacing it with other rock materials forming different geoelectrical zones. Figure 10: A 3D illustration of the major detected subsurface geoelectric zones in the study site, where (**a**) is the first geoelectric zone representing the wadi deposits, (**b**) is the second geoelectric zone corresponding to medium sand, and (**c**) is the third geoelectric zone representing the muddy sand (saturated with groundwater). Figure 11: Horizontal slices of electrical resistivity at depths of (**a**) 0.51 m, (**b**) 3.8 m, (**c**) 6.53 m, (**d**) 9.85 m, (**e**) 16.16 m, and (**f**) 21.49 m from the ground surface that were sliced from the block diagram (Figure 9).