Abstract
The Kyushu Regional Development Bureau of Japans Ministry of Land, Infrastructure, Transport and Tourism (MLIT) has progressed shore protection facilities construction project at 4 sites of Beppukou Coast which consists of Shoningahama, Mochigahama, Kitahama-1, and Kitahama-2 in Beppu city, Oita. The project intends to create Sato-hama, the coastal zone which the residents can be proud of. Kitahama-1 area is the target site of this study and has had problems on aging of existing structures and insufficient protection capacity. The development plan of the coastal protection has been examined by government-private sectors cooperation since 2010, catering to coastal environment and use as well as coastal protection, aiming at the start of construction in 2012.
The development plan has decided through public involvement and "double parapet shore protection" is adapted as the type of protection structure, in which two parallel parapets on the top of seawall and a permeable layer between the two parapets are arranged. The development plan also includes an arrangement of anti-spray zone behind the backward parapet of setback line for coastal use and scenery. As technical investigation of the structure, the height of parapet and the width of permeable layer are important factors for preventing from wave overtopping, and the optimum combination of them has been examined through physical and numerical models.
