Field observation of sediment suspension in the surf zone

Shin, Seung-Ho; Kuriyama, Yoshiaki

Journal of Navigation and Port Research 2003;27(4):455-463.
Published online September 30, 2003.

碎波帶의 底質浮游에 관한 現地觀測

신승호, 栗山善昭

Field observation of sediment suspension in the surf zone

Seung-Ho Shin, Yoshiaki Kuriyama

Abstract

Time series of suspended sediment concentration, surface elevation and velocity were measured and analysed to investigate the role of waves and the predominance of infra gravity wave component for sediment suspension phenomena in the surf zone. For the investigation in detail, we adopted the cross spectral analysis method between suspended sediment concentration and the characteristic values of wave, and ensemble average analysis method about long period wave component, which is dominant to sediment suspension in the measurement point. The obtained results are summarized as follows: 1) The relationship between suspended sediment concentration and the characteristic values of wave is stronger for the long-period standing wave components(about 60s and 30s where the nodal point of the first mode and the anti-nodal point of the second mode are located at the measurement point, respectively) than the long wave components(about 100s), which ave the most energetic power, 2) and also, it is cleared that suspended sediment concentration is increased in the case of the phase, the velocity components of the first mode long period standing wave(60sec) were accelerated toward on-shore direction, that is, the water surface in offshore side is higher than on-shore side.

Key Words: cross 스펙트럼 분석;ensemble 평균; Surf zone;Suspended sediment concentration;Velocity;Surface elevation;Cross spectral analysis;Ensemble average;Long period standing wave;Field observation