HYDROGEOLOGICAL INVESTIGATION IN SALEM DISTRICT

Abstract

Prof. Sri Niwas and Singhal (1981, 1985) theoretically derived two equations using ohm's law of current flow and Darcy's law for porous medium, e.g. the aquifer, which relates the transverse unit resistances and longitudinal conductance of aquifer with the transmissivity of aquifer. Hydraulic conductivity is inversely correlated with resistivity for resistive basement case. In case of conducting basement, hydraulic conductivity is directly proportional to the resistivity. The study area, Salem district, is underlain entirely by Archaean Crystalline formations with recent alluvial and Colluvial deposits of limited areal extents along the courses of major rivers and foothills respectively. Weathered and fractured crystalline rocks and the recent Colluvial deposits constitute the important aquifer systems in the district. The major part of the district is covered by red insitu and red Colluvial soils. The district is a part of Cauvery and Ponnaiar river basins and Sarabanga, Tirumanimuttar, Vasista and Suveda are the important watersheds/sub basins. Major water bearing formations are Colluvial deposits and weathered & fractured granite, Charnockite & granite gneiss. In major parts of district, water conductivity is more than 1000 micromho/cm. Aquifer water is saline in nature. The depth of ground water vary between (0-20) m, whereas the thickness of aquifer (1- 25) in major part of the district. Different contour map has been drawn to delineate hydraulic parameters and porosity of porous medium. The north-west part of the district shows significant well groundwater conditions than other parts of the district.