## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Polygon \#**} & \multirow{2}{*}{\begin{tabular}{c} **K** \\ **(m/Day)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **\(\Phi\) (\%)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Formation** \\ **Factor (F)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Aquifer** \\ **(Ohm-m)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Multiers** \\ **Thickness (m)** \\ \end{tabular} } & \multirow{2}{*}{**Tortuosity**} & \multirow{2}{*}{
\begin{tabular}{c} **Transmissivity** \\ **m2/Day** \\ \end{tabular} } \\ \hline  
\hline \end{tabular}
\end{table} 
Table 4: Interpreted aquifer parameters based on VES and the estimated hydraulic parameters. Tortuosity calculated for 17 polygons that represent the area is presented in Table 4. This indicates that high tortuosity corresponds to low porosity and affects aquifer transmissibility and pore connectivity. The computed final values of hydraulic conductivity varied from 4.5 to 85.6 m/day affect the natural flow of fluids in the aquifer while tortuosity value ranges from 13 to 20. Transmissivity is an important parameter in assessing the aquifer potential and can be computed by using Equation (6) [17; 64]. It describes the capacity of the aquifer to transmit groundwater wholly in its entire saturated thickness [89] ([PERSON] et al., 2021). It can also be defined as the rate of flow of water through a vertical strip of the aquifer [90]. \[\text{T}=\text{Kb} \tag{6}\]  
where K is hydraulic conductivity (m/day) and b is the thickness of the aquifer measured in meters. The thickness of the aquifer is estimated for each VES by using IXID software which is given in Table 4. The evaluated thickness of the aquifer varies from 57 to 183 m. The transmissivity values of the aquifer vary in a large range (674 to 8986 m\({}^{2}\)/day) due to strong contrast in the aquifer lithology. The very low transmissivity, hydraulic conductivity, and formation factor are associated with fine-grain sediments. These fine-grain sediments are mainly sand with silt/minor clay and comprise the aquifer of sandy plain zones. Apparent resistivity (\(\rho_{\text{a}}=\Delta\text{V}/\text{I}^{*}\) K) computed in the field at different depths is an average value of various subsurface layers and does not represent the true electrical characteristics of the individual subsurface layer. Since resistivity values exhibit large variations with some repetition, the number of subsurface layers revealed by the resistivity survey do not often match with the results obtained by trial boring. Layers encountered by trial boring shall be greater in number than layers interpreted by resistivity survey. Apparent resistivity values are not a true representation of the subsurface lithology until they are matched with the theoretical master curves drawn manually or through computer modeling. The VES data collected at 50 probes were modeled by using the IXID Computer Software that gives the model interpretation of individual curves stating/reflecting the number of layers, their true resistivity values with thickness, and depth from the surface. From 50 points, some of the points are near the existing water well/test holes that were used for calibration purposes to correlate the true resistivities with subsurface permeable and impervious layers. These standardized values were applied to the rest of the probes and interpreted the subsurface lithologies. Subsurface geological material as depicted from resistivity modeling was composed of layers of sand, clay, and silt mixed with gravel/sand. The dominant subsurface encountered at all sites (given in Table 1) consists of sand containing fresh, saline, and brackish water. The sand formation containing freshwater indicated high resistivity values as compared to sand containing saline water.