Weather Correlated Short-Term Dynamics in Certain Water Quality Parameters of the Ganga River in Low-Flow Conditions

The effects of prevailing weather on short-term dynamics of certain water quality variables in low-flow conditions were studied in the Ganga river stretch at Allahabad, India. Mean temperature and light intensity showed general diel pattern with significant (p < 0.001) higher values in the afternoon, while significant high rate of change (p < 0.001) was observed in evening wind speed. Total dissolved solids (TDS), total suspended solids (TSS) and turbidity were quite high and displayed a general variable pattern significantly (p < 0.05) associated by evening winds. Wind speed exhibited a significant negative correlation with Chl-a and positive correlation with TSS (r2 = 0.48 and 0.74, p < 0.05, respectively). Afternoon temperatures affected the rate of change of water temperature which was also significantly correlated with dissolved organic carbon (DOC) (r2 = 0.79, p < 0.001). DOC was significantly correlated with the TDS levels (r2 = 0.80, p < 0.001). No correlation existed between average flow (9.50 ± 0.51 m3 s−1) and the tested water quality parameters, while it exhibited strong correlation with the water temperature (r2 = 0.89, p < 0.05). The results indicate that the low-flow conditions during summer may make the river water a complex turbid system where afternoon temperature and evening winds have significant influences on the short-term dynamics and may partially mask the general diurnal patterns of certain water quality variables. The study indicates complex interactions among weather and water quality parameters in low-flow conditions which warrant more elaborative studies. Constant monitoring is recommended to find out an optimum flow to reduce the chances of weather influenced pollution aggravation in this important river stretch.