Groundwater is critical to the socioeconomic development of any region. Infiltration of surface water into the ground is influenced by a variety of factors such as soil pores, folds, fractures, faults, and joints, all of which contribute to groundwater recharge. Groundwater is an important source of freshwater in the drought-prone Pudukkottai district of Tamil Nadu, India. Therefore, the search for groundwater potential zones (GWPZs) is critical. The present study focuses on the investigation of potential groundwater zones using geospatial techniques. Geology, land use and land cover, geomorphology, soil, drainage density, lineament, and groundwater levels were obtained from state and non-state associations. ArcGIS version 10.8 was used to create all thematic layers and classified grids. The intensive use of groundwater in arid and semiarid regions is becoming a problem for the public to meet their freshwater needs. The condition of arid and semi-arid regions due to intensive groundwater extraction has become one of the most important environmental problems for the public. In this study, a powerful groundwater potential mapping technique was developed using integrated remote sensing data from GIS-AHP. Using AHP techniques, thematic layers for geology, geomorphology, and soil followed by drainage, drainage density and lineament, lineament density, slope, water level, and lithological parameters were created, classified, weighted, and integrated into a GIS environment. According to the results of the study, it is estimated that 14% of the groundwater potential in the study area is good, 49% is moderate and 36% is poor. A groundwater level map was used to verify the groundwater potential. In addition, the model was validated with a single-layer sensitivity analysis, which showed that geology was the most influential layer and water level was the least influential thematic layer. The low-potential areas identified on the groundwater potential map can be used for further study to identify ideal locations for artificial recharge. In low potential areas, the groundwater potential map can be used to find ideal locations for artificial recharge. The water table in the area must be raised by artificial recharge structures such as infiltration basins, recharge pits, and agricultural ponds. Artificial recharge structures such as infiltration basins, recharge pits, and agricultural ponds can be used for groundwater development in the low potential zones. The GWPZ map was successfully validated with three proxy data, such as the number of wells, groundwater level, and well density, obtained from well inventory information. The results of this study will improve our understanding of the geographic analysis of groundwater potential and help policy makers in this drought-prone area to create more sustainable water supply systems.

Ramanathapuram is a drought-prone southern Indian district that was selected for conducting a hydrogeochemical study. Groundwater samples from 40 locations were collected during January 2020 (pandemic interdiction according to COVID) and January 2021. The hydrogeochemical properties of the groundwater samples were evaluated and compared with drinking water regulations to assess their water quality. The order of cation dominance was as follows: Na⁺ > Ca²⁺ > K⁺ > Mg²⁺ in January 2020 and Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ in January 2021 with respect to the mean value. The order of anion dominance was as follows: Cl⁻ > HCO₃⁻ > SO₄²⁻ > NO₃⁻ > F⁻ in January 2020 and Cl⁻ > SO₄²⁻ > HCO₃⁻ > NO₃⁻ > F⁻ in January 2021 with respect to the mean value. In the study area, the southern coastal region was identified as a groundwater-polluted zone through spatial analysis based on all analysis results. The irrigation water quality was analyzed using various calculated indices, such as Na% (percent sodium), SAR (sodium absorption ratio), PI (permeability index), MgC (magnesium risk), RSC (residual sodium concentration), and KI (Kelly ratio), demonstrating the suitability of the groundwater for irrigation in most parts of the study area. This was also confirmed by the Na% vs. EC Plot, USSL, and Doneen’s Plot for PI. In addition, the WQI results for drinking water and irrigation confirmed the suitability of the groundwater in most parts of the study area, except for the coastal regions. The dominant hydrogeologic facies of Na⁺-Cl⁻, Ca²⁺-Mg²⁺-SO₄²⁻, and Ca²⁺-Mg²⁺-Cl⁻ types illustrated by the Piper diagram indicate the mixing process of freshwater with saline water in the coastal aquifers. Rock–water interaction and evaporation were the main controllers of groundwater geochemistry in the study area, as determined using the Gibbs plot. Ion exchange, seawater intrusion, weathering of carbonates, and the dissolution of calcium and gypsum minerals from the aquifer were identified as the major geogenic processes controlling groundwater chemistry using the Chadha plot, scatter plot, and Cl⁻/HCO₃⁻ ratio. Further, multivariate statistical approaches also confirmed the strong mutual relationship among the parameters, several factors controlling hydrogeochemistry, and grouping of water samples based on the parameters. Appropriate artificial recharge techniques must be used in the affected regions to stop seawater intrusion and increase freshwater recharge.

Hydrogeochemical analysis was carried out to assess the suitability of groundwater for drinking, domestic, agriculture and industrial purposes in Sivagangai district, which is economically backward district of Tamil Nadu, India. Seventy ground water samples were collected during pre and postmonsoon season in the year 2017 from all over the district and analyzed for hydrogen ion activity, electrical conductivity, total dissolved solids, total hardness, Ca, Mg, Na, K, Cl, CO₃, HCO₃, SO₄, total nitrate, and F. All the analytical results are compared with the corresponding guideline values of drinking water standards and the results show that groundwater in most part of the study area is potable except for a few locations in both seasons. The groundwater geochemistry is mostly controlled by rock water interaction and evaporation processes in both seasons as revealed from the Gibbs plot. The irrigation water quality parameters such as SAR, Na% and RSC results show that some of the groundwater samples are fit for agriculture. It is ascertained through hydrogeochemical analysis that the quality of groundwater is appropriate for drinking, domestic use, agriculture as well as industrial purpose and it can be utilized for industrial development to improve the socioeconomic status of the study area.