Evaluation of groundwater quality in the Chotanagpur plateau region of the Subarnarekha river basin, Jharkhand State, India

Suitability study of groundwater for domestic and irrigation purposes was carried out in the middle Subarnarekha river basin, Jharkhand. Collected samples were analysed for physicochemical parameters such as conductivity, total dissolved solids (TDS), pH, and heavy metals. After the physicochemical analysis groundwater samples were categorised for simplicity, accordingly, it shows that 52.6% samples fall in Ca-Cl₂, 33.3% in Ca-HCO₃, 10.5% in Ca-SO₄, and 1.7% samples in Mg-HCO₃ and rest were Na-Cl type. Interpretation of hydro-geochemical data suggests that leaching of ions followed by weathering and anthropogenic impact (mainly mining and agricultural activities) control the chemistry of groundwater in the study area. The TDS concentration at Govindpur site varies from 2677 mg L⁻¹ in the pre-monsoon to 2545 mg L⁻¹ in the post-monsoon season that is higher than the BIS (2004-05) maximum permissible limit (2000 mg L⁻¹). The elevated concentration of NO₃⁻ was identified at Govindpur, Hatia Bridge, Kandra, Musabani, Saraikela, Mango and Tatanagar. The higher NO₃⁻ concentration was due to the action of leaching and anthropogenic activities. At most of sampling locations, the concentration of Cd, Pb, and Ni were found higher than the prescribed limits defined by BIS and WHO. Groundwater suitability for drinking purpose was also evaluated by the synthetic pollution index (SPI), it suggests that 74%, 95%, and 21% samples fall in seriously polluted category during pre-monsoon, monsoon, and post-monsoon season, respectively. The calculated values of SAR, Na%, RSC, PI, and MH have shown that except at few locations, most of groundwater samples are suitable for irrigation purposes.