ABSTRACT

A three-dimensional mathematical model is developed which is applied to study sediment transport under gales in radial sand ridge area in the South Yellow Sea. MIKE21 SW model is used to simulate waves under gales and FVCOM model is applied to compute currents field and sediment transport. In radial sand ridge sea area, sediments are easy to be picked up or settle down under waves caused by gales because of the properties of the sediment and hydrodynamics. In the FVCOM_SED module, bed load is classified by median particle size and the suspended sediment is calculated by three-dimensional sediment diffusion equation. The wave-tidal-sediment model is applied to the Yangkou Port in radial sand ridge sea area. The results given by the wave-tidal-sediment model show that the present model works well and could be used to simulate the sediment transport in the radial sand ridge sea area under gales.

INTRODUCTION

Sediment movement in the coastal area has a huge impact on the erosion and deposition of the coast and the deformation of the beach boundary, and it will also bring about problems such as the scour of the bottom of the building and the sedimentation of the channel. Since the 1990s, a large number of scholars at home and abroad have worked tirelessly for the development of the numerical simulation of sediment transport in the estuary and coast, and made outstanding contributions in the field of sediment research. The research on sediment mathematical models has been greatly developed. In the study of suspended and bottom sand transport and river bed evolution, Luo (2004) derived a prediction formula for near-bottom sediment transport and channel sudden sedimentation under waves and currents. Horvat and Horvat (2020) applied the derived equations to develop open channel water flow, sediment transport and bed evolution models, and conducted a series of preliminary numerical tests on them. On the basis of considering the characteristics of silt and silt sand, Zhang and An (2012) constructed a mathematical model that can simultaneously simulate the movement of two different types of sediment. At present, due to the rapid development of the computer level and the continuous improvement of theoretical knowledge, sediment mathematical models are also widely used in solving various coastal and estuary dynamic problems, such as estuary regulation projects, port and waterway engineering, etc. Liu and Cai (2019) established a three-dimensional wave-current-sediment coupling numerical model to understand the sediment transport dynamics of the Pearl River Estuary. Yang and Lu (2015) established a two-dimensional mathematical model of the water and sediment transport process in the estuary coast and applied it to the Severn estuary in the United Kingdom. Li, Ouyang, Pan and Yang (2014) established a two-dimensional mathematical model of tidal current and sediment under the action of waves in coastal estuaries, which has a good application prospect. Ding, Kong and Zhu (2011) established a 3-D suspended sediment transport numerical model under combined waves and currents for the estuary and coastal areas. Zhang (2017) used the ECOM model to study the problem of sudden sedimentation of deep-water channels in estuaries under waves caused by gales. These outstanding scholars have made great contributions to the numerical simulation of sediment movement, making the sediment mathematical model play an extremely important role in the estuary and coastal area.

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