Perpustakaan Digital ITB

With a total area of 1.9 million km2, or over 17,500 islands, and a coastline of 99,083 km (Setiawan, 2022), Indonesia is the largest island nation in the world and possesses a significant amount of marine resources, both offshore and along the coast. Waves with irregular shapes and a high potential energy of 17.9 GW are one of the oceanic phenomena that occur in Indonesia (Ministry of Energy and Mineral Resources, 2019). This suggests potential risks, particularly along coastlines where ocean waves may erode the coast or harm nearby structures. In order to stop these negative impacts, the coast must be protected. Mangrove forests are one type of naturally occurring coastal protection that is frequently found in Indonesia. According to extensive research on mangroves' performance (Husrin et al., 2012; Johnson et al., 2018; Rao et al., 1999; Schmitt et al., 2014; Strusiska-Correia et al., 2014; Hashim & Catherine, 2013; Yuanita et al., 2018, 2019, 2020, and 2021). Mangroves are very effective at protecting the coast from erosion and wave damage. However, immature seedlings might be harmed and carried away by the ocean waves while creating artificial mangrove forests as coastal protection. In order to allow the mangroves to grow properly, an additional temporary protection must be made for at least two years (Yuanita et al., 2021). A geobag breakwater structure is one of the many temporary defenses that can be employed. A geobag is a bag filled with materials like sand, stones, and other similar elements that is formed of geotextile materials, preferably biodegradable. Even in the most isolated locations, geobags can withstand both vertical and horizontal deformations (Yuanita et al., 2021). This study focuses on wave transmission caused by random waves that pass through a natural coastal protection system. The method makes use of mangroves as coastal protection and a geobag dike as a temporary barrier. The data was gathered from earlier physical studies utilizing a narrow wave flume and a 1:10 model scale. Genetic algorithm simulations are conducted using the data to optimize the physical paramaters and obtain the most optimum configuration. Based on the simulations, the most optimal configuration of the natural coastal protection sysem used a breakwater slope of 1:2, geobag unit weight of 2 kg, and used in wave steepness conditions of 0.0038 – 0.004. These configurations optimized performance of wave height reduction by 16% - 35%.