Author(s): Octareza Siahaan; Hiroshi Takagi; Matthijs Bos

Linked Author(s): Matthijs Bos

Keywords: Coastal flood Wave overtopping Hybrid structures Mangroves Seawall

Abstract: Jakarta is the Capital of Republic of Indonesia that expands in low lying coastal area. Frequency of coastal floods has been increasing these days and will be exacerbated by sea-level rise and land subsidence. Due to growing economic and population in this city, disaster risk would be further increased. In order to reduce the coastal flood risk, the Government of Indonesia plans to protect coastal area by constructing the tall coastal dike with a height of 4.8 m. Since design wave height of 100 years return period is 3.5 m, the height of the dike seems to be sufficient to prevent high waves. However, this new dike would cause many issues: for example, the dike appears too high for fisherman to access to the sea. In addition, a narrow tall dike may suddenly collapse due to a structural failure or unprecedented events such as a collision of ship or earthquake. In order to avoid such future risks, the authors propose a novel hybrid structure, which aims to lower the height of coastal dike without losing safety level by combining the elements of mangrove, landfill, and dike. Physical experimental was conducted with model scale 1:20. The authors also conducted site survey to adequately model mangroves of Jakarta. Based on the overtopping discharge, a non-dimensional graph is proposed to simply convert the quantity to real scale discharge. The cost of proposed hybrid structure is also estimated and compared with that of an existing coastal dike structure, demonstrating the proposed hybrid solution can be considered as an alternative solution of the planned tall dike by the government.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P2029-cd

Year: 2025