Delineation of groundwater potential zone by integrating groundwater quality parameters using geospatial techniques and multi-criteria decision analysis - a case study on Chennai coastal watershed, Tamil Nadu, India

This study incorporates the Groundwater Quality Index (GQI) to alter the conventional groundwater potential zoning to quantity-quality potential zoning in the Chennai coastal region, which is experiencing groundwater decline and quality deterioration. Using Analytical Hierarchy Process (AHP), weights for twelve thematic layers were assigned and are superimposed with a weighted overlay technique. Pre- and post-monsoon groundwater quantity-quality potential zone (GQQPZ) are classified into poor, moderate, good, and very good zone using pre-and post-monsoon GQI, respectively. Furthermore, the study revealed that seasonal changes also influence the quantity-quality potential zone of the study area. According to the study, the poor zone areas changed from 3.58% to 0.94% due to reduced concentration of pollutants and increased quantity of groundwater during monsoon rain. The validation is carried out with pre and post-monsoon Electrical Conductivity (EC) for pre and post-GQQPZ and resulted in an accuracy of 88.5% and 89.3%, respectively.