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Unravelling heterogeneities in the coastal basaltic aquifer in Saurashtra, India by airborne electromagnetics.

Maurya VP, Mishra A, Chandra S, Rani P, Akhil P, Choudhury J, Kumar KL, Rao NS, Sonkamble S, Nagaiah E, Veerababu N, Singh KP, Verma SK, Singh SK.

NEAR SURFACE GEOPHYSICS

https://doi.org/10.1002/nsg.70017 

Airborne transient electromagnetics, along with limited calibration and validation from bore wells, have mapped the heterogeneities of the coastal basaltic aquifer and the extent of saline zones (~ 40-60 km) and/or salt ingress. The east-west aligned water divide for surface flow rivers and/or drainages is found to be directly associated with resistive basaltic uplands that control the subsurface conditions for groundwater flow and/or accumulation. This study also recommends limited groundwater extraction and prior assessment of recharge potential for long-term aquifer sustainability, especially in arid and semi-arid regions like Saurashtra.

AEM resistivity correlation with yield (left panels) and quality (right panels) observed in the Saurashtra region: (a and b) show the borewells mainly falling over the basalts lying south of Rajkot; (c and d) show remaining borewells over the saline zones and Dhrangadhra formations for the coastal basaltic aquifer settings. (e) Spatially constrained smooth inversions (SCI)-based 3D AEM resistivity model over the study area along with borewells, reservoirs, Bhadar River and some prominent hydrogeological features (weathered and, or fractured basalt, amygdaloidal basalt, massive basalt, sandstone and shale, coastal alluvium etc.) are also marked. Some important locations are also shown over it.

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