A Study on Characteristics of Current and Sediment Transport Around Permeability Artificial Reefs
- Kyu-Han Kim (Catholic Kwandong University) | Kyu-Tae Shim (Catholic Kwandong University)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- PIV analysis, Artificial reef, transmission rate, beach erosion countermeasure, current pattern, hydraulic model test, wave dissipation
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- 17 since 2007
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In this study, effectiveness of artificial reef which is installed increasingly for the beach erosion countermeasure has been reviewed. The wave dissipation rate of artificial reef consisting of permeability blocks was examined through hydraulic model test. The blocks applied to the test consisted of 12 types with different porosity and shape, and the transmission rates of the blocks according to structural characteristics were compared. From the test result, two blocks which have most efficient wave dissipation rate are selected and adapted to topography change experiment. In addition, a change in the wave and flow patterns around the artificial reef according to the plane arrangement including the number of openings, offshore distance, and structure length was examined, and their effects on the beach stabilization were considered based on the experiment result.
Recently, the frequency of incident high waves is increasing in most coastlines of Korea in comparison to the past, and continuous loss of sand has resulted in beach erosion. Also, a cold air mass from China enters the East Sea during winter season, creating a sudden low pressure which induces high waves with longer periods (Oh, 2010). When such high waves are propagated to the coast, a large amount of sediment transport occurs and increases in its duration lead severe erosion. Various methods to control such incidents which high waves cause beach erosion and to protect the sandy beach effectively have been suggested. And among those countermeasures, artificial reef has been mainly constructed in Korea. The crest of artificial reef is located below the surface of water so that it does not interrupt the surrounding landscape, reduces waves and control the beach transport at the same time. Keinomatsubara Coast in Japan is the one of the representative examples where the artificial reefs have been installed with offshore breakwater and T-type groin on the same shoreline. Change in the rear of this coast has been monitored for few years and monitoring result showed that a strong tombolo was formed at the rear of offshore breakwater, causing cutoff of the coast basis of the breakwater and deposition around the groin and erosion between groins were observed. Nonetheless, almost no change around artificial reef remaining the same width of the sandy beach at the time of installation was confirmed. There are more than 130 places where effective in beach protecting artificial reefs are installed or being installed for the last 5 years carried out in Japan in early 2000s.
|File Size||1 MB||Number of Pages||6|