Final closure of the Saemangeum tidal dike, South Korea

A 33 km long sea dike has been constructed in the Saemangeum coastal waters in the mid-west area of South Korea. The project, which reclaims a surface area of 40 100 ha, includes well-developed tidal flats, two estuaries of the Mankyeong and Dongjin rivers, and a chain of small islands in the outer area off the dike. Three open gaps in the project needed to be closed off. The northern opening of the dike was closed on 10 June 2003, whereas the other two 2·7 km gaps were simultaneously closed on 21 April 2006. A method of combined vertical and horizontal closure was successfully applied to block off the gaps. The method was a conventional scheme that consisted of gradually raising the sill level over the full length of the openings and subsequently dumping rocks and gabions transported by trucks. The use of a bag-type gabion mixture with rocks contributed significantly to the successful completion of the final closure despite the very strong currents.