Author(s): Akira Tai; Simon Neill; Matthew Lewis; Hideo Oshikawa

Linked Author(s): Akira Tai, Simon Neill, Hideo Oshikawa

Keywords: ROMS; Resuspension; Wave; Tidal current

Abstract: Sediment transport within the estuary area has important implications, not only for disaster prevention and utilization problems in coastal areas such as coastal erosion and shipping route burial, but also environmental conservation such as water quality and habitat. In previous studies using a sediment transport numerical model, only the tidal current is considered in the majority of cases, and there are few studies that also consider the influence of sea surface waves. In this research, in order to clarify the sediment transport in estuarine regions such as the Ariake Sea, we investigated the effects of sea　surface waves and tidal current on sediment transport using the field　observation data of the Ariake Sea. We used a sediment transport　numerical model considering the influence of sea surface waves and tidal currents in order to analyse resuspension phenomena in the Ariake Sea.The sediment transport model presented here is comprised of the Regional Ocean Model System (ROMS) and Simulating Waves Nearshore (SWAN) models. ROMS is a three-dimensional, free surface, terrain-following numerical model that solves finite-difference approximations of the Reynolds-averaged Navier–Stokes (RANS) equations using the hydrostatic and Boussinesq assumptions with a split-explicit time stepping algorithm. SWAN is a wave-averaged model that solves transport　equations for wave action density. SWAN sends near-bottom orbital velocity to ROMS, and the effect is added to the bottom shear stress. By using the coupled ROMS–SWAN model, we obtained improved validation against field observations when considering both tidal current and sea surface waves, compare to the tidal current only case. Therefore, when considering sediment transport in estuaries, it may be necessary to consider both tidal current and sea surface waves.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022172

Year: 2022