泥沙可侵蚀性对伶仃洋泥沙输运影响的模型实验研究

    Experimental Study on the Impact of Seabed Erodibility on Sediment Transport in Pearl River Estuary

    • 摘要: 泥沙可侵蚀性(临界侵蚀切应力)是水沙数学模型的一项重要参数,直接影响模拟的准确性。为探究河口地区泥沙可侵蚀性对泥沙运动的影响,本文采用嵌合泥沙固结模式的ECOMSED三维水沙数学模型,模拟了珠江河口(重点关注伶仃洋区域)不同临界侵蚀切应力下泥沙运动过程,分析了大潮、小潮及台风条件下不同泥沙临界侵蚀应力对伶仃洋悬沙质量浓度和泥沙运动的影响。结果表明,泥沙临界侵蚀应力是河口地区泥沙输运的重要影响因素,水体悬沙分布、海床冲淤等受到临界侵蚀应力影响显著。随着临界侵蚀应力的减小,水体高浊度区的悬沙质量浓度显著提升,且范围扩大,有向下游扩展的趋势。当临界侵蚀应力为基准值的1/2时,进入南海的泥沙的比例变化不大;当临界侵蚀应力为基准值的1/8时,进入南海的泥沙比例增幅明显。本研究揭示了泥沙可侵蚀性对泥沙运动的影响,可为水沙数学模型的底沙参数设置提供参考。

       

      Abstract: The erodibility of sediment is a crucial parameter in water-sediment numerical models, directly impacting the accuracy of them. To study the influence of seabed erodibility on sediment transport in estuarine areas, a three-dimensional water-sediment mathematical model ECOMSED was adopted, incorporating a sediment consolidation mode. The sediment transport processes in the Pearl River Estuary was well simulated, mostly focused on the Lingdingyang area, with different critical erosion shear stresses conditions. The results indicate that the critical erosion stress is a crucial factor influencing sediment transport in estuarine areas, significantly affecting the distribution of suspended sediment in water and the erosion and deposition of the seabed. As the critical shear stress decreases, the suspended sediment concentration in the originally high-turbidity areas increases markedly, with an expanded scope and a tendency to spread downstream. When sediment consolidation is overlooked, the suspended sediment concentration rises, and its scope expands downstream and to the east. When the critical erosion stress is half of the baseline value, there is little change in the proportion of sediment entering the South China Sea. However, when the critical erosion stress is one-eighth of the baseline value, there is a noticeable increase in the proportion of sediment entering the South China Sea, suggesting that the critical erosion stress of sediment also influences the exchange of sediment between the estuary and the open sea. This study reveals the impact of seabed sediment erodibility on sediment movement and provides a theoretical reference for the setting of bed sediment parameters in water-sediment mathematical models.

       

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