Predicting oxygen content downstream of weirs, spillways and waterways

P. Novak, Consultant In his paper the author has made a very useful contribution to the subject of prediction of oxygen content downstream of spillways, particularly in the case of surface aeration. However, some of the analysis referring to previously published results of oxygen uptake at hydraulic structures is not always rigorous enough. 40. The equations quoted for Avery and Novak apply to clearly de®ned cases. Thus the equation for an overfall applies to a solid, that is not aerated jet falling into a pool of water the depth of which is at least equal to the optimum depth which is a function of discharge and height of fall. The air entrainment in this case is due to the shear layer at impact of the jet into the poolÐa form of air intake neglected in the author's text, although it is the most frequent one at barrages and low weirs. 41. When applying the resultant equation