Fluvio-deltaic aquifers are the primary source of drinking water for the people of Bangladesh. Such aquifers, which comprise the Ganges-Brahmaputra-Meghna Delta, are hydrogeologically heterogeneous. Because of widespread groundwater quality issues in Bangladesh, it is crucial to know the hydrostratigraphic architecture and hydrochemistry, as some aquifer units are contaminated, whereas others are safe. Geophysical methods provide a potentially effective and noninvasive method for extensive characterization of these aquifers. This study applies and investigates the limitations of using electrical resistivity imaging (ERI) for mapping the hydrostratigraphy and salinity of an aquifer-aquitard system adjacent to the Meghna River. Some electrical resistivity (ER) sections showed excellent correlation between resistivity and grain size. These suggest that ERI is a powerful tool for mapping internal aquifer architecture and their boundaries with finer-grained aquitards which clearly appear as low-ER zones. However, in parts of some ER sections, variations in electrical properties were determined by porewater resistivity. In these cases, low ER was indicative of brine and did not indicate the presence of finer-grained materials such as silt or clay. Accordingly, the following hydrostratigraphic zones with different resistivities were detected: (1) aquifers saturated with fresh groundwater, (2) a regional silt/clay aquitard, and (3) a deeper brine-saturated formation. In addition, shallow silt/clay pockets were detected close to the river and below the vadose zone. ERI is thus a promising technique for mapping aquifers versus aquitards; however, the observations are easily confounded by porewater salinity. In such cases, borehole information and groundwater salinity measurements are necessary for ground-truthing.

氟三角洲含水层是孟加拉国人民的主要饮用水来源。包含恒河-布拉马普特拉-梅格纳河三角洲的此类含水层在水文地质上是非均质的。由于孟加拉国普遍存在地下水水质问题，了解水文地层构造和水化学至关重要，因为某些含水层单元已被污染，而另一些则是安全的。地球物理方法为广泛表征这些含水层提供了一种潜在的有效且非侵入性的方法。本研究应用并调查了使用电阻率成像（ERI）绘制与梅格纳河相邻的含水层-阿奎塔尔系统的水文地层和盐度的局限性。一些电阻率（ER）断面显示出电阻率与晶粒尺寸之间的极好的相关性。这些表明，ERI是一个强大的工具，可用于绘制内部含水层结构及其边界以及更细粒度的海quit（显然显示为低ER区域）。但是，在某些ER剖面的某些部分中，电性能的变化是由孔隙水电阻率决定的。在这些情况下，低ER表示盐水，并不表示存在较细颗粒的物质（如粉砂或粘土）。因此，发现了以下具有不同电阻率的水文地层带：（1）含水层被新鲜地下水饱和；（2）区域淤泥/粘土阿基亚德；（3）较深的盐水饱和了的地层。此外，在靠近河流和渗流带下方发现了浅层淤泥/粘土袋。因此，ERI是一种用于绘制含水层与水基分布图的有前途的技术。然而，观察结果容易与孔隙水盐度混淆。在这种情况下，要进行地面钻井，必须提供井眼信息和地下水盐度测量值。