Delineating crystalline basement aquifers with adequate capacity to store and transmit sufficient groundwater is quite challenging as substantial spatial variability predominantly marked the basement aquifers. Electrical resistivity is a non-invasive geophysical technique for delineating weathered and fractured zones that permit groundwater accumulation in the basement rocks. This study uses two-dimensional (2D) electrical resistivity imaging (ERI) to delineate the weathering profile developed above the crystalline basement rocks and thus assesses the groundwater potential of the aquifer systems in Basiri, Ado-Ekiti, southwestern Nigeria. The study evaluated the reliability of the 2D ERI images by computing the depth of investigation (DOI) index to predict the depth extent at which the 2D resistivity models are no longer reliable. This approach can be used to minimise the mismatch between the resistivity models and subsurface targets, particularly in complex and subtle hydrogeological conditions as in the crystalline basement complex. This study indicates that the weathering profile developed into a two-layered aquifer system—a low yield shallow saprolite aquifer overlying a deeper fractured bedrock (saprock) aquifer with greater capacity to support adequate drawdown for high yield.

界定具有足够存储和传输充足地下水能力的结晶地下蓄水层非常具有挑战性，因为主要的空间变异性是地下蓄水层的主要标志。电阻率是一种非侵入性的地球物理技术，用于描绘风化带和断裂带，这些带允许地下水在地下岩石中蓄积。这项研究使用二维（2D）电阻率成像（ERI）描绘了结晶基底岩石上方形成的风化剖面，从而评估了尼日利亚西南部Ado-Ekiti的Basiri含水层系统的地下水潜力。该研究通过计算调查深度（DOI）指数来预测2D电阻率模型不再可靠的深度范围，从而评估了2D ERI图像的可靠性。这种方法可用于最小化电阻率模型与地下目标之间的失配，特别是在复杂而微妙的水文地质条件下，如在结晶基底复合物中。这项研究表明，风化剖面发展为两层含水层系统，即低产浅腐泥土含水层，覆盖在较深的裂缝基岩（边坡）含水层上，具有更大的能力来支持充足的压降，以实现高产。