Assessment of surface water quality and its spatial variation. A case study of Ramganga River, Ganga Basin, India

Ramganga River is the main tributary of the Ganges River which is the most sacred and largest river basin of India. For effective management of Ganges, assessment of water quality in its tributaries is must, and this river lacks it so far. The present study focuses on the evaluation of water quality of this river and its adjoining tributaries. Organic pollution indicators, chemical oxygen demand (COD) and biological oxygen demand (BOD5) of river water ranges from 15.2 to 55.5 mg/L and 7.1 to 29 mg/L, respectively. Nutrient parameters nitrate (NO3−-N) and phosphate (PO42−-P) of river water ranges from 0.2 to 12.7 mg/L and 0.02 to 0.76 mg/L, respectively. While in tributaries, these parameters range from 0.2 to 9.9 mg/L and 0.03 to 1.47 mg/L, respectively. The most polluted stretches of river were from Moradabad to Farrukhabad via Bareilly especially in terms of organic pollution. Pair sample t test applied to compare the water quality of river and its tributaries revealed no significant difference in COD, NO3−-N, PO42—P, and fluoride (F−) while sulfate (SO42−) was significantly large (25.1 mg/L) in tributaries. The spatial variation in water quality of river was addressed by cluster analysis (CA) which grouped the 16 sampling points into three significant clusters corresponding to lower pollution, moderate pollution, and severe pollution regions. The results from CA restructure the entire sampling campaign to a cheaper and less-effort sampling program that will be helpful in water quality assessment and management of the river.