Evaluation of incipient-aeration point on spillways

Determination of the inception point for self-aeration is of great importance in the design of dam spillways. Several semi-empirical methods have been presented to calculate the location of this critical point. This paper examines the order of prediction errors and the degree of reliability from the application of current methods in compare with available experimental data on the incipient-aeration point, both in model and prototype. The results indicate that the relationships ofWood, et al. (1983), Keller & Rastogi (1977), and Ferrando & Rico (2002) are accurate enough for preliminary design purposes. An average underestimation of 1% should be considered with an order range of error between −44% and +58%. Computational procedure is illustrated by several examples of dam spillways in Iran, on the anticipated location of the critical point and its possible deviation from the average predicted value.