MEASUREMENT OF REFLECTION COEFFICIENT OF SEAWALL IN OMORA BAY

Kosuke Kondo, Masayuki Akama, Masahiko Isobe

Abstract


Field investigations were performed in order to establish the reflecting characteristics of a steel sheet-piling type seawall and two vertical wave-dissipating type seawalls through directional wave measurements of wave reflection systems. A pre-designed line array of several capacitance-type wave gauges was used to measure the wave field just in front of the seawall, and the MMLM (Modified Maximum Likelifood Method) was applied for the calculation of the directional wave spectrum and the reflection coefficient. The estimated directional spectra demonstrated that the MMLM has high resolution power and can sufficiently separate the incident and the reflected wave energies. As a result , it was found that the reflection coefficient of the vertical steel sheet-piling seawall is about 0.9 and is independent of the incident wave conditions, whereas those of the vertical wave-dissipating type seawalls show considerable change in correlation to the incident wave period or the mean water level.

Keywords


Omura Bay; reflection; reflection coefficient; reflection measurement

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