Delineation and mapping of groundwater quality in Salem district: A comprehensive assessment of contaminant sources

A comprehensive study was conducted at block level in Salem District, Tamil Nadu, India, to evaluate the major ionic chemistry and to assess the suitability of ground water for irrigation purpose. A total of 200 groundwater samples were systematically collected through grid survey and analyzed for major ionic constituents and irrigation water quality parameters. The resulting water quality parameters were interpreted based on established hydrochemical guidelines. The classification of groundwater samples under various quality categories based on pH, electrical conductivity (EC), residual sodium carbonate (RSC) and sodium adsorption ratio (SAR) indicates that many blocks (70 %) in the study area exhibit good-quality groundwater suitable for irrigation. However, exceptions (30 %) were observed in the blocks of Omalur, Mecheri, Kolathur and Pethanaickenpalayam having been observed with saline and alkali water quality. This might be due to the underlying metamorphic and crystalline rocks carrying the element calcium and sodium rich minerals are responsible for the development of saline/alkali groundwater. It was observed that mushrooming of industrial complexes in these blocks might also be the reasons for the development of saline or alkali groundwater. The need for this work is to evaluate groundwater quality for irrigation in Salem District and identify areas affected by saline and alkali contamination due to natural and industrial influences.