Understanding the hydrochemical behavior of groundwater and its suitability for drinking and agricultural purposes in Pondicherry area, South India – A step towards sustainable development

• Groundwater quality in different aquifers of coastal Pondicherry were evaluated for drinking and irrigation suitability.
• Majority of the water samples fall within permissible limits for drinking and irrigation.
• Temporal variation indicated 100-300 µS/cm raise in electrical conductivity in groundwater.
• Cretaceous aquifer has good quality water compared to Tertiary and Quaternary aquifers.
• Better usage of tanks and artificial recharging of groundwater would be help in improving the quality and quantity of groundwater.

Optimal utilization of groundwater in Pondicherry area is needed to ensure future wellbeing of this region as the demand for water is exponentially increasing due to population growth. A study was carried out with an objective to assess the groundwater quality in different aquifers for its suitability to drinking and agriculture usage. The current trends in chemical quality were compared to that of historical data in order to ascertain the declining quality of groundwater in this region. Results indicate that excepting a few anomalies most of the parameters were within the permissible limits. pH, calcium, magnesium and chloride concentrations were high in 20%, 20%, 48% and 10% of the analyzed samples respectively, as compared with BIS (2012) prescribed limits. Indicators such as SAR(adj), RSC and Na% that qualify the water for irrigation suitability were found to be under permissible to excellent category. A few water samples fall under doubtful to unfit category, which could be due to presence of high bicarbonate. A comparison with historical data indicates that salinity (EC) and sodium hazard have been higher in the present scenario and the increase in electrical conductivity was found to be about 100–300 µS/cm. Statistical analysis of the data indicated that rock weathering and saline water have affected the groundwater chemistry in this region in addition to contributions of anthropogenic activities. A combination of tank rejuvenation and artificial recharge of groundwater by rainwater can yield better results for improving not only the groundwater quality but also quantity in this region for future times.