长江口12.5 m深水航道悬沙分布特征

摘要

Based on the hydrologic data of the Yangtze estuary 12.5 m deepwater channel in the flood season and dry season, we analyze the spatial and temporal distribution of suspended sediment concentration. The result reveals that suspended sediment concentration in the south channel & Yuanyuansha and the middle section of the north passage is small, and its vertical distribution is relatively uniform. But in the middle section of the north passage, the suspended sediment concentration is high and the vertical distribution is uneven. Fine sediment flocculation, fresh and salt water mixing and stagnation point may be the main reasons for the high suspended sediment concentration in the bottom of the middle section of the north passage and large differences in the vertical distribution of the flood season. The high suspended sediment concentration in the middle section of the north passage and in the flood season is consistent with the characteristic of temporal and spatial change of 12.5 m deepwater channel siltation, indicating that siltation in the north passage resulting from the suspended sediment’s deposition. The suspended sediment concentration in the south channel&Yuanyuansha is significantly lower than that in the north channel, and the vertical distribution is relatively uniform, which indicates that the contribution of channel siltation from suspended sediment silting may be small.%利用长江口12.5 m深水航道洪、枯季水文测验资料，分析深水航道悬沙的时空分布特征。结果表明：南港圆圆沙段含沙量小，垂线分布相对均匀；北槽中段含沙量大，垂向分布不均匀。细颗粒泥沙絮凝、盐淡水分层与河口滞流点是北槽中段形成高含沙量且垂向分布不均匀的主要原因。北槽中段含沙量的时空分布特征，与12.5 m深水航道的回淤变化特征具有一致性，表明北槽中段的航道回淤可能以悬沙淤积为主；而南港圆圆沙段含沙量低，且垂向相对均匀，表明该区段航道回淤受悬沙的影响较小。