SEDIMENTATION AND WAVE ATTENUATION BY<i> Avicennia marina </i>MANGROVES: IMPLICATIONS FOR SUSTAINABLE COASTAL PROTECTION

Abstract

Mangrove ecosystems protect coastlines from abrasion and erosion, attenuate strong sea breezes, and bind sediments periodically. A mangrove ecosystem can be set up to be a coastal building capable of breaking and reducing natural waves, but only through certain calculation methods, so that it serves as a solution by being an environmentally friendly breakwater alternative for sustainable coastal development. The objective of this study was to determine the effects of sedimentation by Avicennia marina mangroves on wave attenuation. Spot-check, transect-squared, and laboratory test methods were employed in this research. The wave data measurement performed using with SBE 26 and RBRDuo T.D. The measurement was performed at five stations at distances of 3 m, 5 m, 10 m, 20 m, and 50 m. The wave attenuation at the 5 stations was 49.5%, 53.8%, 82.9%, 91.4%, and 92.3% with grain diameters of 19.36%, 19.75%, 19.87%, 21%, and 27%. The higher the wave attenuation percentage, the lower the grain diameter percentage, and vice versa. When the waves came, the energy was so large that all the large particles of the sediment in the sea were carried back to the mangrove ecosystem, and when the waves left, the energy released was so small that only the small particles were carried back to the sea. The conclusion is that the diameter percentage of mangrove sediment is related to the percentage of wave attenuation. The higher the wave attenuation percentage is, the smaller the grain diameter percentage will be.