## 3 Results and Discussion
### EM38-MK2 Results  
Twenty profiles using the EM38-MK2 in the vertical mode were conducted to measure the apparent electrical conductivity (ECa) at 75 and 150 cm depths, based on implemented coil separation (0.5 and 1 m separation in vertical mode). The data from about 2240 measuring points sites acquired by EM38-MK2 were automatically logged by a special Data Logger Allegro CX. It is worth mentioning that ten of the EM38-MK2 profiles of measured electrical conductivity had the same locations of the measured 2-D profiles, while the other ten electrical conductivities lines measured by EM38-MK2 were measured five meters away from the location of the 2-D and the EM38-Lines-Ones of electromagnetic. The exported electrical conductivity (ECa) values for each EM38 measuring line were averaged for the values measured at 1 m coil separation and those measured at 0.5 coil separation. For every ten lines, the electrical conductivity (salinity indicator) was plotted for both two different coil separations (1 m and 0.5 m). Figure 11 shows the combined averaged measuring lines using EM38-MK2 across the Al-Ahsa Oasis. Investigations of these lines show how the  
Figure 9: An image shows the dug pits and the shallow water table beside profile 1 (P-1, Figure 8). variation of conductivity changed with depth, according to the positions, due to changes in soil salinity conditions, lithology, and soil texture at each line. The following remarks can be noticed from Figure 11.  
The measured conductivity at lines located at the southwest of the study area was characterized by relatively low conductivities (maximum was 140 mS/cm), see for example, Line 4 (Figure 12a) as compared with those lines measured at the north and east of the study area, see for example, line 7, Figure 12b (maximum was 750 mS/cm), which was about five times the maximum electrical conductivity at line 4 (P-4, Figure 12). These indicate the salinity of the soil at the north and east part of Al-Ahsa Oasis. The two evaporator lakes of Al Uyoun to the north and Al Afar to the east are the main reasons for the salinity increasing at these locations. It is worth mentioning that there was a good match between the results of the 2-D profiles and the EM38-MK2 profiles for the soil zones. For example, the topsoil of resistivity profile 5 (P-5) was resistive, see Figure 8, which was confirmed by relatively low conductivities (maximum was about 150 mS/cm). On the other hand, compared with those lines measured at the north of the study area, see resistivity profile 1 and the EM38-MK2 for this profile for the soil zones; they are characterized by high conductivity (low resistivity). Generally, the measured conductivity at most lines indicated high values of conductivities at a coil separation of 1 m (greater depth); see for examples Lines 7, 8, and 10 of Figure 12b, c, and d, which are located at the north and east of the study area, while only two lines (line 4, Figure 12a) and line 3 (P-3, Figure 12) showed high values of conductivities at a coil separation of 0.5 m (shallow depth) compared with those at a 1 m coil separation, located in the southwest of the study area. Figure 10: Some excavation and the existing hardpan layer at different depths near profile 6 (P-6, Figure 8). Figure 11: The combined averaged measuring lines at the ten tested locations from 1 to 10 (P-1 to P-10) using EM38-MK2 across the Al-Ahsa Oasis. Figure 12: Electrical conductivities along Em38 at four tested locations (P-4, P-7, P-8, and P-10). Lines 4 at P-4 (**a**), Line 7 at P-7 (**b**), Line 8 at P-8 (**c**), and line 10 at P-10 (**d**) across the Al-Ahsa Oasis; for location see Figure 11.  
These results are an excellent match with what was reported by [PERSON] [21]. [PERSON] [21] reported that soil chemical properties exhibited slightly alkaline pH values between 7.33 and 7.86, while, the soil salinity data, as EC values, varied across the Al-Ahsa Oasis.