Comparative analysis of land use and lake water quality in rural and urban zones of south Chennai, India

Abstract

Chennai city, the capital of Tamil Nadu state in South India, has been experiencing rapid expansion since the last two decades, resulting in major changes in land use and degradation of wetlands. Small lakes in the peri-urban areas face severe strain on their environment due to transition of rural to urban conditions, leaving at stake their aquatic health and intended uses. This paper studies the role of urbanization and land use changes in the water quality of peri-urban (Rajakilpakkam) and rural (Vengaivasal) lakes. Water samples were collected and analysed for temperature, total dissolved solids, major ions, nutrients and biological oxygen demand as per standard methods. The temperature, pH and biological oxygen demand did not differ between lakes, while total dissolved solids (p = 0.008), alkalinity (p = 0.000), total hardness (p = 0.001) and phosphate (p = 0.000) were significantly higher in Rajakilpakkam. Seasonal and spatial variations in water quality between the lakes showed the direct impact of rapid and uncontrolled growth of built-up areas in the catchment area, in enhancing waste water inflows with inorganic salts and nutrients in Rajakilpakkam lake compared with Vengaivasal lake. Urbanization of the catchment and encroachments in Rajakilpakkam lake tends to reduce the social interdependence of lake and community and promote disuse, leading to decline in water quality. The impending environmental costs caused by urbanization to these lakes will only be tackled, if the main issues of domestic and industrial discharges and encroachments are addressed properly.