南黄海辐射沙脊群潮汐水道的悬沙输运特征

Suspended sediment transport patterns in the tidal channels in the southwestern Yellow Sea

根据南黄海辐射沙脊群定点站位的流速和浊度数据,利用通量分解方法,分析了潮汐水道的悬沙输运特征和输运机制。结果表明,辐射沙脊群海域潮汐水道中潮流为往复流,悬沙浓度较高,属于强潮流控制的悬沙浓度相对较高的陆架浅海环境;悬沙输运主要受欧拉余流和潮汐捕捉效应控制,再悬浮的沉积物通过平流作用进行输运。其中,陈家坞槽和西洋水道的悬沙输运以潮汐捕捉效应占优,沉积物向潮汐水道外输运,处于冲刷状态;苦水洋水道以欧拉余流输运为主,水道内的再悬浮的沉积物在强潮流作用下向陆输运,主要堆积在蒋家沙和西洋西侧岸滩等浅滩和潮间带上。由此可见,在陆源物质供应减少背景下,南黄海辐射沙脊群内部的物质充当了新的物源,短期内能够维持近岸潮滩和沙脊的持续增长。

Based on the measured current velocities and suspended sediment concentration data for the tidal channels between the radial sand ridges in the southwestern Yellow Sea, this study analyzed the mechanism of suspended sediment transport in the channels. The flow in the study area was rectilinear, and the suspended sediment concen- tration was relatively high. The decomposition of sediment fluxes suggested that the Eulerian effect and tidal trap- ping were the main factors affecting suspended sediment transport. In the Chenjiawu and Xiyang tidal channels, tid- al trapping was a dominant mean for suspended sediment transport,and sediments were entrained from the channels by tides, which indicated the existence of the process of seabed scour. In contrast, the main controlling factor for suspended sediment transport in the Kushuiyang channel was the Eulerian effect, and the resuspended sediments were transported towards onshore by the strong tide flow and then piled up at Jiangiiasha and over shoal or inter- tidal areas on the western coast of Xiyang. Thus,under the circumstances for reducing terrigenous material input, sediments in the radial sand ridges became a new source of material supply and played an important role on the con- tinued accretion of the sand ridges and the adjacent tidal flats.