Abstract Hard rock hydrogeology has a range of complexities due to differential weathering and fracturing. Systematic non-invasive geophysical characterization of hard rock formations is warranted to acquire adequate knowledge of fractured aquifer systems for effective groundwater management. Hence, continuous lateral and depth-wise resistivity measurements using multiple electrode arrangements have been carried out in southern India’s granitic hard rock terrain to delineate saturated fracture zones for groundwater prospecting. The inverted resistivity models reveal distinct geoelectrical contrasts with weathered zone exhibiting resistivity values below 100 Ωm and compact bedrock exceeding 3000 Ωm. Electrical resistivity tomography (ERT) provides a strong signature of clusters of bedrock fractures containing water that are characterized by resistivity values ranging from 100 to 500 Ωm, with minor fractures reaching resistivity values as high as 1500 Ωm. This study further provides a comprehensive approach for interpreting and translating electrical resistivity information into a detailed lithological model integrated with knowledge of borehole camera logging and geology. It is an effective method for accurately mapping the transitions between weathered layers and fractures in a hard rock environment, which is crucial for building a precise hydrogeological model. This study emphasizes the effectiveness of the ERT method as a non-invasive tool for groundwater prospecting in complex hard rock terrains for sustainable water management. Research highlights <UnorderedList Mark="Bullet"> <ItemContent> The paper shows the effectiveness of noninvasive geophysical technique, especially Electrical Resistivity Method (ERT) in identifying saturated fractures forming hard rock aquifers. </ItemContent> <ItemContent> ERT successfully resolves and differentiates various subsurface layers, including the saturated near-surface layer, weathered zone, fissured zone, and massive bedrock, aiding in the accurate characterization of geological and hydrogeological properties. </ItemContent> <ItemContent> A comprehensive approach integrates ERT data with borehole camera logging and geological knowledge, providing a more detailed and accurate interpretation of the subsurface. </ItemContent> <ItemContent> Creating accurate hydrogeological models for sustainable water management in complex hard rock environments. </ItemContent> </UnorderedList>

Unravelling subsurface complexity to characterize hard rock aquifers using electrical resistivity tomography

期刊论文
发表日期：

2026年2月23日

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Joy Choudhury,
Subash Chandra,
S K Begum,
E Nagaiah,
Abhilash K Paswan

摘要

Abstract

Hard rock hydrogeology has a range of complexities due to differential weathering and fracturing. Systematic non-invasive geophysical characterization of hard rock formations is warranted to acquire adequate knowledge of fractured aquifer systems for effective groundwater management. Hence, continuous lateral and depth-wise resistivity measurements using multiple electrode arrangements have been carried out in southern India’s granitic hard rock terrain to delineate saturated fracture zones for groundwater prospecting. The inverted resistivity models reveal distinct geoelectrical contrasts with weathered zone exhibiting resistivity values below 100 Ωm and compact bedrock exceeding 3000 Ωm. Electrical resistivity tomography (ERT) provides a strong signature of clusters of bedrock fractures containing water that are characterized by resistivity values ranging from 100 to 500 Ωm, with minor fractures reaching resistivity values as high as 1500 Ωm. This study further provides a comprehensive approach for interpreting and translating electrical resistivity information into a detailed lithological model integrated with knowledge of borehole camera logging and geology. It is an effective method for accurately mapping the transitions between weathered layers and fractures in a hard rock environment, which is crucial for building a precise hydrogeological model. This study emphasizes the effectiveness of the ERT method as a non-invasive tool for groundwater prospecting in complex hard rock terrains for sustainable water management.

Research highlights

The paper shows the effectiveness of noninvasive geophysical technique, especially Electrical Resistivity Method (ERT) in identifying saturated fractures forming hard rock aquifers.

ERT successfully resolves and differentiates various subsurface layers, including the saturated near-surface layer, weathered zone, fissured zone, and massive bedrock, aiding in the accurate characterization of geological and hydrogeological properties.

A comprehensive approach integrates ERT data with borehole camera logging and geological knowledge, providing a more detailed and accurate interpretation of the subsurface.

Creating accurate hydrogeological models for sustainable water management in complex hard rock environments.