Seasonal Variations and Groundwater Quality Assessment for Drinking Purpose in Chengam Taluk of Thiruvannamalai District, Tamil Nadu: A Geomatics Approach.

Groundwater is the major source of drinking water in rural as well as urban areas in India and over 94% of the drinking water demand is met by groundwater. The current study aims to evaluate the availability of safe groundwater for drinking and its seasonal variations in quality during pre-and post-monsoon seasons in the Chengam Taluk of Thiruvannamali district, Tamil Nadu, India. With the aid of BIS2012 and WHO2004 edition, six water quality parameters such as pH, Ca, Cl, EC, Mg and TDS have been taken to evaluate the groundwater quality status of the Taluk. The samples were collected from 7 locations and their physicochemical parameters, such as pH, TDS and EC were measured in situ using the portable kit and Ca, Mg, and Cl, were analyzed in the laboratory. For the preparation of the spatial distribution map of low to high groundwater-contaminated regions, GIS-based spatial interpolation with inverse distance weighting and MCDA (weightage overlay) methods have been used. According to the study results, the concentrations of chemical parameters in the groundwater are more in the central and northern parts of the Taluk compared to the south and south-eastern part. Groundwater quality is in its worst condition (due to over-exploitation, unplanned agricultural and industrial development, unhygienic sewerage with improper methods of toilet waste disposal, etc.) during post-monsoon seasons compared to pre-monsoon for almost all three decades. After evaluating the data, it is concluded that 63% of the sample locations have poor-quality of groundwater which is only suitable for irrigation but not suitable for drinking. There is an instant need to take an ameliorative step to install water purification systems and takes necessary measures for wastewater treatment and improve the groundwater quality of the region. [ABSTRACT FROM AUTHOR]