Assessment of salt water intrusion and irrigation suitability of groundwater in the kollam coast, South India

The Kollam coast in South India is a thickly populated area where the possibility of exploitation groundwater sources and contamination is high. The quality of groundwater is very important for various purposes. For the analysis of groundwater, fourteen dug wells in the seven coastal wards of Kollam Corporation were selected randomly and water samples were collected for the physico-chemical analysis. It was found that all physico-chemical parameters in the well water except total alkalinity, total hardness and, calcium are under permissible limits according to BIS (2012) drinking water quality. Based on the hardness values obtained, 42.9% of the wells are with moderately hard water and 35.7% of the wells in the coastal area are with hard water. Saltwater intrusion in groundwater sources was calculated using Base Exchange Index (BEX) and results show that 42% of wells are having saltwater intrusion. Irrigation suitability of the groundwater samples was measured by calculating magnesium hazard, sodium percent, and sodium adsorption ratio. Magnesium hazards of all well water are below 50%. Based on the sodium percent values obtained, 7% of the well water samples in the study area are under excellent class, 78% of the samples are under good class and 14% of the samples are under permissible class. The values of the Sodium adsorption ratio of all well water samples studied are under excellent class. It indicates that the groundwaters in the dug wells of the coastal area are suitable for irrigation purposes. The study shows that well water in the Kollam coastal area can be consumed after purification. Water purifiers with reverse a osmosis systems can be used to remove hardness and coliforms from the groundwater.