Sea level rise due to climate change is expected to have a significant impact on coastal structures and infrastructure. The majority of rubble mound breakwaters and seawalls along the Australian coast are built to withstand depth limited breaking waves and are vulnerable to changes in sea level - the required size of primary armour units being a cubic function of the breaking wave height.

Breakwater and seawalls where constructed to protect infrastructure and assets will require adaptive upgrading over time to maintain service performance. The timing for such upgrades being investment decisions based on risk assessment. With rising sea levels, increasing water depths and depth limited breaking waves the mass of primary armour units on the outer layer of these structures required for stability will increase significantly. In many cases the armour size will in time exceed the upper limit of available quarry rock and concrete armour units will be used for upgrade work.

This study assesses the possible options for sea level rise adaptation on typical Australian rubble mound structures. 2D physical model testing undertaken in the 1 m wide random wave flume at the Water Research Laboratory (WRL), UNSW is presented as the basis for the adaptation options.