Large Scale Experiments on the Effect of Artificial Reef Restoration on Wave-Driven Flooding

Abstract This paper presents a new set of experiments conducted at near-prototype scale to investigate the impact of artificial reef flat restoration on wave transformation and runup. The experiments were carried out in the 300m-long Delta Flume, which allowed the representation of the entire fringing reef profile and sandy island at a 1: 3 scale. The reef restoration consisted of rows of complex-shaped roughness elements arranged in different layouts. In total, three configurations were tested under five irregular wave conditions and two water levels. All tests were also repeated on a bare (unrestored) reef flat to assess the impact of the restoration. Preliminary data analysis indicates that the artificial reef restoration reduced significant wave heights by up to 13% near the shore for the high-density restoration configuration and the lowest water level. This reduction in wave height was similar for both the sea-swell and infragravity wave frequency bands. Next steps are to examine how the spectral distribution of the (incident) wave energy is impacted by the reef restoration for the different configurations, relate this to flow observations within the artificial canopy and assess the impact on runup characteristics.