Characterizing palaeochannel and multi aquifer disposition in a morphodynamic system of the Ganga river basin in Northern India

Identifying palaeochannels and understanding the multiple aquifer dispositions are crucial for effective groundwater resource management in alluvial plains. This study has employed a high-resolution 2-D Electrical Resistivity Tomography (ERT) survey to delineate palaeochannels and characterize multi aquifer architecture within morphodynamic system of the Ganga river basin, Northern India. A total of nineteen ERT profiles, each spanning 320–480 m with 10 m electrode spacing, were acquired using the Wenner-Schlumberger array with an IRIS Syscal R1+ Instrument (France made) and processed using RES2DINV software, applying the smoothness-constrained least-squares optimization approach. The resulting true resistivity models were correlated with the geomorphic units and lithologies from nearby boreholes. The results have shown that the palaeochannels with the resistivity values ranging from 20 to 60 Ω.m, thickness of 4–40 m, and lateral extents between 40 and 200 m, predominantly oriented in the northeast-southwest (NE-SW) and east-west (E-W) directions. These channels are interpreted as sandy to gravelly deposits interbedded with sandy clay, acting as shallow aquifers, and potential recharge conduits to the first principal aquifer. Additionally, deeper resistive zones (extended up to ~ 90 m, bgl), composed of medium to coarse sands and sandy clays, indicate productive multi aquifer system. The integration of ERT data with geomorphic units and borehole lithology has substantially improved the resolution and confidence in detecting buried palaeochannels, which are typically undetectable through surface geomorphology alone. This study has demonstrated the efficacy of ERT in delineating complex subsurface hydrostratigraphy and identifying critical recharge zones in data-scarce and morphodynamically active alluvial settings. These findings hold significant implications for planning artificial recharge interventions and promoting sustainable groundwater management across the Ganga river plains. Future investigations should incorporate denser borehole networks and complementary geophysical techniques to further refine the understanding of palaeochannel dispositions and multi aquifer systems.