Evaluation of Spatio-temporal Changes in Surface Water Quality and Their Suitability for Designated Uses, Mettur Reservoir, India

Freshwater has a significant role in determining the ecological environment, public health and socio-economic development. This study analyzed the spatio-temporal variation in surface water quality of the tropical reservoir Mettur, India, to determine whether its water is suitable for human consumption and aquatic ecosystem. Thus, 21 water quality parameters were monitored seasonally (pre-monsoon, monsoon and post-monsoon) at nine sampling sites covering riverine, transitional and lacustrine zones of the reservoir during 2018. The study revealed spatial variation, which was due to input from industrial and domestic wastewater in the lacustrine zone of the reservoir. However, temporal variability often exceeded spatial variability. The factor analysis indicates that basin geology, anthropogenic stress and agricultural applications simultaneously act vital roles in deciding the reservoir water quality. Based on similarity of water quality parameters, cluster analysis grouped all the nine sampling sites into three clusters of high, moderate and less polluted sites. Correlation analysis also indicated that multiple sources influence the reservoir water quality during all the seasons. Based on BIS and WHO values, the calculated water quality index (134-158) indicates that water of the reservoir is not fit for human consumption, while the trophic state of this reservoir is moderately-eutrophic to eutrophic. However, with precaution, this aquatic body seems to be suitable for aquatic life and fish growth. The overall water quality deterioration of this reservoir indicates a strong need for development of a regular monitoring system for implementation of an effective management system to safeguard human and environmental health.

Automated summary

This study analyzed the spatio-temporal variation in surface water quality of the tropical reservoir Mettur, India, and found that spatial variation was influenced by input from industrial and domestic wastewater in the lacustrine zone of the reservoir. Despite temporal variability often exceeding spatial variability, factor analysis showed that basin geology, anthropogenic stress, and agricultural applications play crucial roles in determining the reservoir water quality.