Evaluating the Impact of Urbanization on the Physiochemical Parameters of the Urban River System: A Study on Vaigai River, Madurai

The article attempts to investigate the impact of Madurai’s urban expansion on the River Vaigai at the confluence of six channels draining into the river from the urban watershed and at the causeways. Impervious surface cover (ISC) has impacted the river. Water samples were collected during 2017 in 15 stations in the urban stretch and two stations in the peri-urban stretch. Physical characteristics, namely, temperature, colour, odour and taste, and the intensity of chemical parameters, namely, pH, calcium, nitrates, total dissolved solids (TDS), total hardness (TH) and carbon dioxide demand (COD), were estimated. These estimations show that anomalous concentrations of physiochemical parameters in the river are much higher than the permissible standards prescribed by the Bureau of Indian Standards (BIS). The causeway recorded greater variations in TDS levels between the upstream and downstream zone. The study identifies two realities: first, variance in the intensity of physiochemical properties in the urban and peri-urban stretch and second, the impact of causeways on the flow characteristics of the river.