Determination of Grain Sorting in an Accretion Profile Caused by Cross-Shore Sediment Transport

Although the size of the grains forming a coastal profile vary along regions of the coast, studies examining coastal sediment transport have been conducted mostly with a constant grain size and thus have not accounted fully for the influence of the material being transported on sediment transport. Similarly, the previous studies have not considered the effect of irregular waves on the grain distribution of accretion profile. The aim of this study was to investigate the effects of wave height, period, and bed slope on the grain sorting of bed materials in the accretion profile formed as a result of cross-shore sediment transport and thus to obtain information about the effects of grain sorting on coastal morphology. The novelty of this study is that grain size change mechanism in the accretion profile under irregular wave conditions was investigated by using physical model studies. Two-dimensional physical model experiments were carried out with irregular waves. Four wave heights (Hm0 = 4, 5, 6, and 7 cm), two wave periods (TP = 1.57 and 2.18 s), three bed slopes (m = 1/10, 1/15, and 1/25) and three starting sand materials (d50 = 0.26, 0.33, and 0.40 mm) were used, constituting a total of 72 physical model experiments. The accretion profile was divided into five sections (foreshore, crest, ridge, shoreline, and toe), and grain sorting in these sections was determined. The physical model studies showed that finer material accumulated in the ridge of the accretion profiles, while coarser grains were deposited in the foreshore, shoreline, and toe sections. Sediment particles tended to concentrate this predictable distribution in the accretion profile sections.

Automated summary

This study investigates the mechanism of grain size change in the accretion profile under irregular wave conditions using physical model experiments. The results show that finer grains accumulate in the ridge of the accretion profiles, while coarser grains are deposited in the foreshore, shoreline, and toe sections.