| Abstrakt: |
The vertical electrical sounding (VES) method was used in this study to evaluate the subsurface geology and hydrology of Calabar South Local Government Area (LGA). The major goal was to identify places with favourable aquifer features and those that were less susceptible to groundwater pollution. The findings of the VES study indicated a wide range of aquifer resistivity values, lower aquifer resistivities were observed in several regions, notably VES 1, 6, and 9, indicating heterogeneous aquifers with varied groundwater storage and recharge capacity. In contrast, VES 10 and 3 had the highest aquifer resistivity, indicating more favourable groundwater conditions in these areas. The thickness of the aquifer ranged from 11.72 to 26.60 m, with shallower aquifers in the north and deeper ones in the south. The depth to the water table ranged from 19.90 to 54.40 m, demonstrating geographical differences in groundwater accessibility. Transverse resistance values in the aquifer varied from 80.38 to 91,850.28 Ωm, with greater values recorded towards the northwest, suggesting lesser permeability and decreased sensitivity to pollution. The results for longitudinal conductance varied from 0.33 to 279.75 S, whereas hydraulic conductivity ranged from 0.0009 to 0.6728 m/day. VES 9 has the greatest hydraulic conductivity, signifying a better capability for groundwater movement. Transmissivity values ranged from 0.0169 to 15.9362 m2/day, demonstrating variances in the capacity of aquifer segments to convey groundwater. When the VES data were analysed, it was discovered that 70% of the VES locations had high protective capability, making them appropriate for groundwater usage. However, other locations, such as VES 9, had extremely corrosive properties, indicating a modest protective capability. The research area’s groundwater potential varied. Around 40% of VES locations had limited groundwater potential, whilst others, such as VES 5 and 9, had moderate groundwater potential for local water supply. However, VES 3 and 10 showed impermeable groundwater potential, making obtaining local water supply difficult. In conclusion, our research indicates that Calabar South LGA has favourable subsurface geology and hydrology for groundwater storage and recharge. Nonetheless, groundwater potential differs across the area, needing more research to identify specific places with the best prospects for groundwater development. |
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