TITLE:
Groundwater Investigation in Markandahalla Basin Using Vertical Electrical Sounding Data
AUTHORS:
S. Saranya, H. C. Vajrappa
KEYWORDS:
Groundwater Exploration, Electrical Resistivity, VES, Schlumberger Array, Isoresistivity Maps, Hard Rock Aquifers, Total Longitudinal Conductance, Kolar District
JOURNAL NAME:
Open Journal of Geology,
Vol.16 No.8,
August
13,
2026
ABSTRACT: This study employs the electrical resistivity technique to investigate groundwater potential zones in the hard rock terrain of the Markandahalla basin, Kolar district, Karnataka. Fifty-two Vertical Electrical Soundings (VES) were conducted using the Schlumberger array with maximum AB/2 electrode spacing of 360 m. curves were interpreted by standard curve-matching against Rijkswaterstaat (1975) master curves and 1D inversion using IPI2WIN software, accepting models with root-mean-square error (RMSE) ≤ 5%. Isoresistivity maps at AB/2 = 45, 90, 180, and 360 m were generated to delineate subsurface lithology and aquifer zones. Results show that weathered and semi-weathered zones with moderate resistivity values (50 - 250 Ωm) favour groundwater occurrence. Depth to bedrock varies from 1.9 to 27.8 m; Total longitudinal conductance ranges from 0.01 to 1.41. Geophysical interpretations were validated against borehole yield data from 18 existing wells, confirming that sites with ρ2 S > 0.3 Siemens consistently yield > 1.0 lps. The study identifies the central and north-western portions of the basin as the most prospective groundwater target zones.