DIRECT HAZARD FROM WAVE OVERTOPPING: A REVIEW AND FORWARD LOOK

A primary purpose of many coastal defences is to protect people from direct hazard due to wave overtopping. This is reflected by the use of an admissible overtopping as a key parameter in design or assessment of structures. Despite this long-established design driver, it is less than 20 years since guidance on admissible overtopping started to move from being based simply upon mean discharge to consider the volumes associated with individual wave overtopping events. Only in the past five years or so has attention zoomed in further, to associate the influences of direct hazard on the actual flow parameters (typically water depth and speed at the pedestrian). This paper will provide a developed view of the current state of the art and improved guidance, and the research from which it has emerged.