Are floating mangrove breakwaters effective for wave attenuation? - A Literature Review

Abstract

Human-induced global warming, caused by greenhouse gases, raises temperatures and sea levels, posing risks to coastal communities and ecosystems. Interest in nature-based alternatives like mangroves and living shorelines is growing due to their ecological benefits and ability to mitigate waves, protecting vulnerable coastlines. Floating breakwaters have demonstrated promise in attenuating waves compared to their submerged counterparts. Similarly, floating mangroves detached from the shoreline and suspended on the water's surface have emerged as an alternative solution due to their potential ability to reduce wave force while providing additional benefits. This review aims to compile information on field, laboratory, and numerical experiments of floating breakwaters and mangroves testing their efficiency for wave attenuation. We found that floating mangroves have the potential for wave reduction, although this differed among mangrove species, with the highest reduction in Rhizophora (80 %) followed by Avicennia officinalis (55 %), Sonneratia (50 %), and Kandelia candel (20 %). Rhizophora spp was the most studied and likely to be the most effective due to its complex root system. Field trials and feasibility studies showed that testing the wave-reducing ability of this integrated structure is essential to tackle the challenges caused by strong waves. Ultimately, this review seeks to deepen our comprehension of mangrove-based floating solutions. It highlights their significance in protecting coastlines and promoting ecological balance in rising sea levels.