Groundwater quality assessment using geospatial and statistical tools in Salem District, Tamil Nadu, India

Abstract

The water quality study of Salem district, Tamil Nadu has been carried out to assess the water quality for domestic and irrigation purposes. For this purpose, 59 groundwater samples were collected and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), major anions (HCO3−, CO3−, F−, Cl−, NO2− + NO3−, and SO42−), major cations (Ca2+ Mg2+, Na+, and K+), alkalinity (ALK), and hardness (HAR). To assess the water quality, the following chemical parameters were calculated based on the analytical results, such as Piper plot, water quality index (WQI), sodium adsorption ratio (SAR), magnesium hazard (MH), Kelly index (KI), and residual sodium carbonate (RSC). Wilcox diagram represents that 23% of the samples are excellent to good, 40% of the samples are good to permissible, 10% of the samples are permissible to doubtful, 24% of the samples are doubtful unsuitable, and only 3% of the samples are unsuitable for irrigation. SAR values shows that 52% of the samples indicate high-to-very high and low-to-medium alkali water. KI values indicate good quality (30%) and not suitable (70%) for irrigation purposes. RSC values indicate that 89% of samples are suitable for irrigation purposes. MH reveals that 17% suitable and 83% samples are not suitable for irrigation purposes and for domestic purposes the excellent (8%), good (48%), and poor (44%). The agricultural waste, fertilizer used, soil leaching, urban runoff, livestock waste, and sewages are the sources of poor water quality. Some samples are not suitable for irrigation purposes due to high salinity, hardness, and magnesium concentration. In general, the groundwater of the Salem district was polluted by agricultural activities, anthropogenic activities, ion exchange, and weathering.