Hydrogeophysical Investigations in Namagiripettai Area, Namakkal District, Tamil Nadu

Results of high-Density vertical electrical soundings in an over-Exploited area show that the borewell yields are not generally correlatable with any of the geoelectrical parameters. Many of the lineaments mapped from satellite imageries could be identified from geoelectrical profiles/Sections, but the same could not be done from spatial distribution maps of either hydrogeological or geoelectrical parameters. Two lineaments could be identified from the depth to bedrock map, though wells along these lineaments do not necessarily have higher yields. It appears that most of the so-Called lineaments mapped from satellite images/Aerial photographs are in reality, not structures controlling groundwater occurrence and movement, at least in an over-Exploited area, where the water-Bearing zones are at considerable depths. However, the usefulness of both the techniques in identifying deep fractured rock zones is established from the results of the study. In view of the pronounced inhomogeneity present in hard rock areas, it is clear that the soundings must be as close as possible to each other in order to get a clear picture of the sub-Surface.