Noise reduction at a low-head vertical-drop spillway

Nappe vibration and noise generation are more usually associated with spillway gates, but can occur in fixed crest concrete weirs with vertical drops. The paper describes the problem at a site where the noise from a weir created a potential problem for a new residential development. Model testing of various options to reduce the noise is described, along with the physical works on site that reduced the noise to acceptable levels. The results can be used as a guide for designers of low-head spillways at reservoirs as well as at river weirs.