Sediment distribution and transport dynamics in Xiangzhou Bay, Zhuhai

Located at the confluence of an estuary, islands, and headlands, the sedimentary environment of Xiangzhou Bay is critical for coastal sustainability. This study aims to elucidate the distribution and transport patterns of surface sediments in Xiangzhou Bay. Based on in-situ data and grain-size trend analysis, we calculated, for the first time, the sediment starting velocity, resuspension flux, and transport flux in the area, and analyzed the controlling factors. The results show that silt and clay dominate the surface sediments (over 82%), exhibiting an overall fine-grained composition with localized coarser patches, and excellent sorting. The sediment starting velocity ranges from 32 cm/s to 57 cm/s, indicating that tidal currents readily induce sediment resuspension, with a daily resuspension flux from 58.72 kg/m2 to 151.87 kg/m2. The daily net transport flux of surface sediments in Xiangzhou Bay is higher on the northeast side than on the southeast side., exhibiting ebb- and flood-dominated transport trends, respectively, with a sediment convergence zone forming southeast of Yeli Island. The sedimentary dynamic environment is complex. This study suggests that sediment sources are primarily from the Pearl River, resuspension of sediments from the bottom of Lingdingyang Bay, and coastal engineering activities. Sediment transport is influenced by tides, waves, river runoff, and human activities.