Assessing nearshore orbital velocity characteristics for application in sediment transport models

Abstract

Near-bed velocity characteristics directly influence the sediment transport and the evolution of the near-shore profile. A large-scale laboratory data are applied to assess the wave-induced velocity parameters in the nearshore zone and to evaluate the existing empirical models developed to estimate nearshore velocity parameters for application in sediment transport models. The velocity characteristics of regular waves are statistically analyzed and compared with average velocity parameters commonly applied in sediment transport models. The results indicate that the shoreward maximum velocities (Uc) are mostly greater than the seaward maximum velocities (Ut), with a ratio within 1 and 1.7 range. Depending on the water depth and wave condition, incorporated in Ursell number, the time duration of shoreward (Tc) is usually shorter than the seaward (Tt), with a ratio within 0.7 and 1. Among the available empirical models developed for estimating nearshore velocity parameters, Elfrink’s model generally more accurate in predicting orbital velocity parameters. The results are consistent in terms of Uc and Ut though inconsistent in terms of Tc and Tt with the observed velocity characteristics. The comparison of the sediment transport rate by applying the measured values and the velocity characteristics predicted by Elfrink’s model reveal some differences in rate and direction. © 2025 Japan Society of Civil Engineers.