Chattahoochee River Thermal Alterations

A coupled flow-temperature model was applied to a 43.12-mile (69.39-km) reach of the Chattahoochee River starting in the urbanized section of Atlanta, Ga. The water temperature changed as much as 4.4°C while while passing through the reach, and the temperature model was capable of predicting these changes with a root-mean-square error of 0.72°C in July and 0.65°C in August l976. The thermal model was used to estimate the instantaneous as well as the average natural temperatures in the river reach. The average natural temperature predicted by the model (24.92°C) was in excellent agreement with the independent estimate of 24.85°C. The effect of upstream reservoirs and the heated effluent of the Atkinson and McDonough Power Plants nearly cancel one another in an average sense but significantly increase the diurnal range of river temperature.