Abstract:
Modelling of electrical resistivity data especially from coastal area assumes an explicit significance for groundwater
prospecting studies. Direct current (DC) Vertical electrical sounding (VES) data were acquired from 84 locations
around Aronda-Redi-Vengurla-Malvan region, Sindhudurg district, Maharashtra, India, with an objective to decipher
the structural trend for identifying groundwater potential zones of the area using geophysical indicators. The VES
curves obtained were primarily of 3-5 geoelectric layers. One-dimensional inversion results divulge that the top layer
is predominantly comprised of laterites/fractured laterites followed by an assortment of clay/clayey sand and
granulites/fractured granulites as basement rocks. Several NNE-SSW and NW-SE oriented major lineaments and its
criss-crosses have been reported in this region and the source of groundwater appears to be contained in
weathered/semi-weathered layer of laterite/clayey sand at depth of 10-12 m from the surface. Geoelectric parameters
for interpretation included curve type, anisotropy coefficient, fracture porosity, and reflection coefficient. The
electrical anisotropy varied from 1 to 3.95, while the reflection coefficients ranged from 0.1 to 0.99 in the study area. It
is seen that stations with low reflection coefficient revealed higher electrical anisotropy, suggesting an inverse
correlation between these two parameters. The northeastern, southern and northwestern part of the study area
revealed higher values of fracture porosities, wherein a positive relationship with the high and low values of electrical
anisotropy was observed. These results would be helpful for interpreting the geological signatures like fractures, joints
and lineaments for identifying groundwater prospective zones in the coastal area.
