Statistical analysis of reaeration rate in streams

Atmospheric reaeration is often the main source of oxygen in rivers and streams, where oxidation phenomena of organic matter produce depletion of dissolved oxygen in the aquatic systems and, thus, could give rise to low levels, unacceptable for the ecosystem. Therefore, in DO modeling studies, which are addressed to predict in-stream oxygen concentrations, reaeration process must be quantify; some literature formulas are available, but they had been often developed from a little amount of data field or are stream-specific. In this paper statistical analysis was performed on a large amount of field data of reaeration rate Ka, which has been provided by United States Geological Survey (USGS); main statistical parameters were estimated and test for normality was carried out. Particularly, Chi-square goodness-of-fit test confirmed the normal distribution for log (Ka). Finally, field data were compared with the results obtained using 3 well-known reaeration formulas, such as O’Connor-Dobbins, Gibbs-Owens and Parkhurst-Pomeroy, which are often applied in water quality modeling studies.