Hydrogeophysical Assessment of Groundwater Potential in the Deccan Basalt

Groundwater occurrence in the Deccan basalt is highly uncertain. Non-invasive hydro-geophysical techniques, when integrated with a priori geological information, can aid in delineating saturated zones. This study uses electrical resistivity anisotropy with direct current (DC) resistivity and time-domain induced polarization (IP) for delineating groundwater prospects. We utilized the geophysical responses of DC resistivity, induced polarization, anisotropy and available borehole litholog data to locate the potential aquifers. Anisotropic inversion of DC resistivity data enables the identification of fractured basalt. We observed shallow saturation zones where fractured basalt overlies less permeable layers and deeper confined zones below the intertrappeans within fractured amygdaloidal basalts. The most productive shallow aquifers exhibit low to moderate resistivity (1 to 36 Ωm), and moderate to low chargeability (1.1 to 8 mV/V) and anisotropy (1.1 to 1.21). Finally, we conducted aquifer tests in different wells in the study area to quantify the aquifer parameters. This study offers a strong scientific basis for the assessment of groundwater potential zones and their management in the complex basaltic terrains of the Deccan province.