Upgrading Breakwaters in Response to Sea Level Rise: Practical Insights From Physical Modelling

Abstract

Coastal structures in many parts of the world are typically designed for depth-limited breaking wave conditions. With a projected sea level rise of up to 90 cm by 2100 (Church et al., 2013), the design wave height for these structures is expected to increase. Many of these structures will require significant armour upgrades to accommodate these new design conditions (for example, a 25% increase in wave height will require the mass of similar density armour to be doubled).

Performance of a dynamic cobble berm revetment for coastal protection, under increasing water level.

“…In all cases, such modifications are likely to be expensive. Revetment and rock armour upgrades are hard to achieve as the addition of an extra layer of material usually creates planes of weakness (Howe & Cox, 2018). Howe & Cox (2018) suggested that efficient top-up maintenance could be achieved using a higher density layer, however this method is only at the prototype testing stage.…”

Stability of High Density Cubes in Rubble Mound Breakwaters

“…On the other hand, the stability of high density armour blocks was found to be significantly affected by scale effects due to very small units. Van Gent et al (2001) did tests with high density cubes (almost 40 kN/m 3 ) in a traditional double top-layer and single top layer. They revealed that high density cubes are as stable as normal density cubes; i.e., damage occurred for the same or higher values of stability number in double layer case.…”