Ground-based electrical geophysical data calibrated with borehole information are conveniently used to delineate subsurface strata because of their inherent capability to assess the lateral and vertical variations in the pore water. In this study, joined geophysical approach of vertical electrical sounding (VES) and electrical resistivity tomography (ERT) has been steered to define the strata in the hyporheic zone and in the water bearing caches in the Akwa Ibom State University’s littoral shorefront. Four ERTs with each using Wenner array with 5 m electrode spacing were conducted along four profiles at the same locations that VES were conducted. Twelve surface VES soundings were performed with maximum current electrode separations of (AB/2 = 150 m). The integration of formation resistivity with six boreholes reveals motley topsoil/dry strata with resistivity value greater than 200 Ω - m above water table; saturated clay/saline water depository with resistivity value less than 30 Ω - m below water table; fine-grained sand/brackish water depository with resistivity range spanning between 70 and 200 Ω - m below water table; medium-grained sand/freshwater depository with resistivity ranging from 500 to 800 Ω - m below water table and gravelly sand/freshwater depository with resistivity value greater 800 Ω - m below water table were inferred from top to bottom within the maximum current electrode separations. These ranges of resistivity show lithological diversity in subsurface layer. Geochemical analysis was performed for main cations (magnesium, sodium, potassium, calcium, iron and manganese), anions (bicarbonates, sulphates, chloride, and fluoride) and other physical parameters such as, pH, electrical conductivity, total dissolved solids, dissolved oxygen, biochemical oxygen demand and chemical oxygen demand. The results of the interpretation of hydrochemical species of the groundwater samples revealed that the groundwater in most locations within the study area is fresh, slightly alkaline to acidic based on the EC, pH and TDS values. The order of abundance for anions and cations is HCO₃^– > Cl^– > SO₄^2– > F^– and Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ > Fe²⁺ > Mn²⁺ respectively. The observation of elevated BOD with lower DO even in the muddy area suggests anoxic condition (DO < 5 mg/L) rather than oxic condition (DO > 5 mg/L), based on the measured DO values (00.12–2.61 mg/L). The elevated ferric iron concentrations on the surface water, which later seeps into the groundwater systems, are due to excessive accumulation of dissolved organic matter (DOM) and the consequent reduction reaction within the DOM in surface water.

借助钻孔信息校准的地面电地球物理数据可方便地描绘地下地层，因为它们具有评估孔隙水横向和纵向变化的固有能力。在这项研究中，采用了垂直电测深（VES）和电阻率层析成像（ERT）的联合地球物理方法，来确定阿夸伊博姆州立大学沿岸海岸的水流带和含水储层中的地层。在与VES相同的位置沿着四个剖面进行四个ERT，每个ERT使用Wenner阵列，电极间距为5 m。以最大电流电极间隔为（AB / 2 = 150 m）进行十二次表面VES探测。地下水位上方m 地下水位以下电阻率值小于30Ω- m的饱和粘土/盐水储层；细砂/微咸水储层，其电阻率范围在地下水位以下70至200Ω- m之间；地下水位以下电阻率范围为500至800Ω- m的中粒砂/淡水储层，电阻率值大于800Ω- m的砂砾/淡水储层在最大电流电极间距内，从上至下推断出地下水位以下的水。这些电阻率范围显示了地下层的岩性多样性。对主要阳离子（镁，钠，钾，钙，铁和锰），阴离子（碳酸氢根，硫酸根，氯离子和氟离子）和其他物理参数（例如pH值，电导率，总溶解固体，溶解氧）进行了地球化学分析，生化需氧量和化学需氧量。地下水样品中水化学种类的解释结果表明，研究区域内大多数位置的地下水都是新鲜的，根据EC，pH和TDS值，其呈碱性至酸性。阴离子和阳离子的丰度顺序为HCO ₃ ^– > Cl^– > SO ₄ ^2– > F ^–和Na ⁺ > Ca ²⁺ > Mg ²⁺ > K ⁺ > Fe ²⁺ > Mn ²⁺。观察到即使在泥泞的区域中BOD升高且DO较低，根据测得的DO值（00.12–2.61 mg / L），表明缺氧条件（DO <5 mg / L）而不是有氧条件（DO> 5 mg / L） ）。地表水中较高的三价铁浓度随后渗入地下水系统，这是由于溶解有机物（DOM）的过度积累以及随之而来的DOM在地表水中的还原反应所致。