Spatial and seasonal assessment of water quality of Musi River, India

The water quality parameters of the Musi River, Hyderabad, India, were assessed by collecting samples from four stations during post-monsoon, monsoon, and pre-monsoon seasons. The samples were scrutinized according to American Public Health Association standards for their physicochemical and biological characteristics to evaluate the seasonal and spatial alteration in water quality. The water quality was judged using the weighted arithmetic water quality index (WAWQI), Nemerow's pollution index (NPI), irrigation indices and hydrogeochemical facies. A significant spatial and seasonal variation was observed along the Musi River. The average values of WAWQI were calculated as 38, 175, 197 and 179 for Osman Sagar, Bapughat, Musarambagh, and Nagole, respectively. The analysis revealed that water is unfit for consumption at all stations except Osman Sagar as per the Bureau of Indian Standards. Piper diagram was utilized to determine the hydrochemical facies, which illustrated that the water sample at Osman Sagar falls in the category of type-I (${\mathrm{Ca}}^{2+}$- ${\mathrm{Mg}}^{2+}$-${\mathrm{HCO}}_3^{-}$) whereas other stations fall in the category type-II (Na⁺-K⁺-${\mathrm{HCO}}_3^{-}$). Further, all stations except Osman Sagar observed a decline in dissolved oxygen and an increment in biochemical oxygen demand. A long-term management plan and consistent monitoring are recommended to protect the Musi River.