HAZARDS AT COAST AND HARBOUR SEAWALLS – VELOCITIES AND TRAJECTORIES OF VIOLENT OVERTOPPING JETS

This paper describes new research under the VOWS (Violent Overtopping of Waves at Seawalls) project. Established guidance on admissible overtopping volumes is based upon values of mean discharge. In cases where hazard to pedestrians/vehicles are concerned, it is clear that an admissible level of overtopping would be more appropriately based upon the volume of an individual overtopping event. Further, the hazard presented is not only a function of the volume of that overtopping wave, but also of the speed and trajectory of the jet. Methods exist to predict maximum individual overtopping volumes. This paper presents new data and a first predictive tool for overtopping "throw velocities", and first data from a device designed to measure directly the trajectories of overtopping jets.