Appraisal of river water quality using open-access earth observation data set: a study of river Ganga at Allahabad (India)

The present study aims to provide a better understanding for appraisal and monitoring of surface water quality of the river Ganga at Allahabad (India) using open-access earth observation data set. The Landsat 7 (Enhanced Thematic Mapper plus, ETM+) data has been used for this study. The band rationing technique has been employed for this study. Water samples were collected according to the satellite passing. The ratio of the radiances at the sampling sites was obtained and validated with in situ measurements of water-quality parameters. The water-quality parameters were assessed viz. turbidity, pH, chemical oxygen demand (COD), biological oxygen demand (BOD), dissolved oxygen (DO), temperature, alkalinity, and total hardness. Multiple linear regression models were developed based on satellite bands. The result shows that water-quality parameters were significantly correlated with the radiance values of the ETM + image except turbidity. Multiple linear regression equations models were applied on ETM + bands for estimation of water-quality parameters and preparation of water-quality maps for different water-quality parameters of the study area. Moreover, the current study suggests that the Landsat 7 ETM + image can be effectively used for the assessment of water-quality parameters of a river system.