Chromium transport modeling in tannery effluent from a surface water body to groundwater regime: Case study in Kodaganar Basin

Groundwater is the main source of water supply to the public in the upper Kodaganar basin in the state of Tamilnadu in India. Wastewater from the tannery industries of the basin is discharged into Sengulam Lake. For this study, a model was developed to simulate the magnitude and direction of groundwater flow in the aquifer. This model was extended as a chromium-transport model that demonstrated the transport of hexavalent chromium from the lake to the aquifer. The chromium concentration in the lake was found to be 4 mg/L. The chromium concentration in the groundwater of the nearby aquifer ranged from 0 to 2 mg/L. The migration behavior of the chromium was analyzed by the developed contaminant-transport model. The spatial extent of the damage caused in the aquifer by chromium contamination was demarcated by modeling the velocity vectors. It was estimated that the groundwater in an area of about 10 km2 was polluted by chromium. The average velocity of groundwater was estimated to be 1.9 m/day. The time taken for the chromium particles to reach the Kodaganar River was estimated to be 12 years.