Achieving Low Overtopping Limits in the Design of Sloping Rock and Concrete Armour Unit Structures

Due to the need to protect expensive critical infrastructure, low wave overtopping limits were required for a project recently designed in the Arabian Gulf. The project is currently under construction and features revetments and rubble mound breakwaters armoured with rock and concrete armour units.

The overtopping limit that ultimately governed design was 0.4 l/s/m for a 100 year return period storm event. The design of the structures was firstly based on commonly adopted empirical overtopping methods available in Eurotop (2007) and the Rock Manual (CIRIA, 2007) and was subsequently assessed in 2d and 3d physical modeling tests. In some cases, particularly where large crest widths were adopted, the empirical methods were found to estimate overtopping one to two orders of magnitude lower than recorded in the physical model tests. Results and analysis relating to this are presented within this paper.