FIELD OBSERVATION ON MIGRATION AND DEFORMATION PROCESSES OF SAND RIPPLES ON TIDAL FLAT

Abstract

 There are many sand ripples of small size topography on tidal flats. It is essential to grasp the processes of sand ripple deformation and migration because these processes have much influence on sand movement and topographic change in coastal areas. In this study, continuous sand ripples photography in the water was conducted, and the investigation of characteristics of sand ripple’s migration was attempted by comparing with sea conditions and sand ripple shape. The results showed that the sand ripple migration was generated in a limited duration when the water depth was very shallow, and the sand ripple shape became asymmetry and sharp during the migration. It was indicated that strong instantaneous currents greatly affected sand ripple migration. Moreover, it was also inferred that the estimation of sand ripple migration might be possible using the information on wave conditions, water depth and sand diameter in the field.