OBSERVATIONS OF WAVE RUNUP REDUCTION BY POROUS STRUCTURES

Coastal and estuarine flooding and erosion are expected to intensify considerably over the next decades due to sea level rise and increase in extreme storm events. Foreshore managers have typically responded to flooding and erosion threats by constructing hard, impermeable structures (e.g., rock walls, revetments). The downsides of these structures, however, are increasingly recognized, such as loss of beaches, negative effects on ecosystems and substantial installation and maintenance costs. Few studies have focused on wave attenuation by porous structures (e.g., Losada et al., 1995; Requejo et al., 2002), however the influence on wave runup remains largely unknown, particularly its components; setup, and infragravity and sea-swell swash. In this study, we aim to take a first step in filling that gap and evaluated the effect of idealized porous structures on wave runup through experiments in a large-scale wave tank using irregular wave conditions. The experimental findings are considered an important initial step towards better understanding of how bioengineered structures can provide shoreline protection and shelter for habitat restoration, and towards the development of quantitative design guidelines.