OBSERVATION OF SAND RIPPLES AND ESTIMATION OF SEDIMENT TRANSPORT ON A TIDAL FLAT

Abstract

 The presence of sand ripples on the seafloor indicates the occurrence of sediment movement. And that greatly affects the amount of sediment movement there. In this study, the shape change of sand ripples and their movement on a tidal flat were observed by continuous image shooting of sand ripples and measuring waves and currents. The movement of sand ripples in one direction was confirmed by analyzing the sand ripple images. It was also found that at the observation points of this study, waves and water depth were the main factors for the generation of sand ripple movement, and wave conditions controlled the sand ripple length. In estimating the amount of sediment movement in the presence of sand ripples, a quantitative estimation of the amount of sediment movement was not achieved in this study. However, the possibility of the quantitative estimation by setting an appropriate observation range was confirmed. Furthermore, we recognized the importance of considering the presence of ripples in estimating sediment movement in the sediment transport formula.