Role of winter waves in sand transport at the mouth of Garolim Bay, west coast of Korea

摘要

Sedimentary processes on the west coast of Korea are strongly influenced by monsoonal climate with strong northwesterly winds during winter. Sediment transport processes under winter storm waves are, however, poorly known, because of the difficulties of field observations. For the assessment of the influence of winter waves on sediment transport processes over a sand bank at the mouth of Garolim Bay, bedload transport by combined currents and waves is quantitatively estimated using the current data measured at the bay mouth and representative parameters of winter waves, and is compared with that by tidal currents alone. Our results show that high winter waves have a significant influence on the spatial pattern, the amount, and the directions of bedload transport through the bay mouth. Under the condition of combined currents and waves, bedload transport increases considerably due to the increase in bed shear stresses, particularly in shallow water depths of the sand bank. Increases in bedload transport are more pronounced during the flood current than the ebb current, resulting in a net increase of bedload transport into the bay. It is, thus, concluded that wintertime high waves reinforce sand import into the bay and probably onto the sand flats near the mouth. Our results can be applied to other bays and estuaries that have openings allowing the influence of winter waves, given that sufficient bedload sediments are available.