Hydrogeochemical Studies of Kabini River Basin, Karnataka, India

The quality of ground water in the Kabini river basin, covering an area of 7040 sq km₂ in Karnataka, has been studied based on the composition of one hundred sixty one borewell water samples. An attempt has been made to classify the ground water by various methods. According to Bureau of Indian Standards, 97% of the water samples in the study basin are within the desirable to permissible limit. 93% of the samples fall in C₂-S₁ class of USSL diagram. According to Wilcox diagram, 91% of samples fall within the excellent to permissible classes. In the Hill-Piper diagram, majority of the groundwater samples fall in the Ca, Mg-CO₃, HCO₃, and Na, K-CO₃, HCO₃ hydrochemical facies. This has been attributed to highly weathered and fractured nature of the basement rocks. By plotting on modified Hill-Piper diagram, it is found that majority of the samples have non-carbonate hardness with a salinity ranging from 2.5 to 23 epm. It is inferred that groundwater of the area has low sodium hazard and low to medium salinity. The range of dissolved components, the values of SAR and residual sodium carbonate indicate that 97% of the water samples of the basin are suitable for domestic, irrigation and industrial purposes.