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In recent years, the extraction of groundwater (GW) in coastal aquifers has rendered the fragile aquifers more saline due to the sea water intrusion. Groundwater from the coastal aquifers of the Pudhucherry region were sampled to study the process of salinization. An integrated approach was adopted to identify the salinization process, by coordinating the results of borehole geophysics, rainfall pattern, water level variation, hydrochemical characters and multivariate statistical analysis. A total of 136 groundwater samples were collected during two different seasons, southwest monsoon (SWM) and northeast monsoon (NEM). The major cations and anions were analyzed adopting standard procedures. Resistivity and litholog indicate that the southeastern (SE) part of the study region has lower resistivity than in north. Based on electrical conductivity (EC) and total dissolved solids (TDS) values, most of the samples are potable, except for few samples from southeastern region. The study results indicated that higher values of Na, EC, K, SO4, Mg and Cl were observed during NEM, indicating leaching of salt into the aquifer and ion exchange process. The predominant hydrochemical facies of groundwater was Na-Cl and Ca–Mg–Cl type reflecting the saline water and the mixing process of saltwater and fresh groundwater, respectively. Though more number of samples with higher EC was noted in NEM, the results of PCA and correlation analysis indicate the predominance of leaching of salts and intense agricultural activities. The process of sea water intrusion was observed to be dominant during SWM.

The irregular monsoonal rainfall and overexploitation of groundwater have resulted in the sharp decline of water resources in different parts across India. Various factors like geology, terrain morphology, hydrology, and hydrometeorology influence the recharge potentiality of a region. Application of remote sensing and geographical information system (GIS) tools might be effective in the delineation of groundwater recharge potential zones and help towards the sustainability of groundwater resources. In this study, it was attempted to identify the groundwater recharge potential zones in the Courtallam region located at Tamil Nadu state of South India by integrating multiple thematic layers involving lithology, geomorphology, land use/land cover, slope, lineament density, drainage density, and the spatial distribution of groundwater level and rainfall through weighted overlay analysis in Arc GIS. The recharge potential was compared with the electrical conductivity of groundwater for evaluating the water quality. It was characterized the groundwater recharge potential of the study area as very poor (8.7%), poor (32.5%), moderate (37%), good (16.3%), and very good (5.5%). one-third of this area has moderate groundwater recharge potentiality and the southeastern part of the study area with good quality of water is feasible for new bore-well construction.