Surface and Subsurface Geoelectrical Investigations to Explore the Fresh and Saline Water Zones in Parts of Chidambaram Taluk,Cuddalore District, Tamil Nadu, S. India

摘要

The stress on water resources has started due to exploding irrigation, domestic and industrial demands. Pollution in air and surface water has been of great concern. However, relatively less attention is given for subsurface-groundwater contamination in different parts of the world. Among different problems pertaining to groundwater, salinity, pollution and sea water intrusion are the most predominant resulting in the environmental degradation. The Electrical Resistivity Technique (ERT) is widely adopted technique for ground water contamination studies. In this study both surface and sub surface Electrical Resistivity Techniques (ERT) have been used to delineate potential freshwater zones in saline environment for agricultural and drinking water purposes. The study area is about 120 sq. km of areal extent, a part of Chidambaram Taluk, in Cuddalore district of Tamil Nadu, South India. The groundwater salinity is a common scenario in most parts of the taluk and depth of saline water contamination varies from place to place. The study area is a coastal sedimentary terrain confined between the rivers Vellar and Kollidam. The area is covered by Quaternary unconsolidated sedimentary formations of fluvial, fluvio marine and marine facies. An innovative approach has been attempted to demarcate the deep confined freshwater aquifers by generating isoresistivity maps for different depths from normal resistivity derived from resistivity logging. At Pannapattu a good yield of 760×10-6 has been met, with very good quality water (EC 625 μmhos/cm@ 25 ℃ and TDS - 498×10-6). Thus the studies have helped in delineating the contaminated saline and fresh water zones. The saline water contamination is in situ in nature due to the marine origin sediments.