庙岛海峡周边海域表层沉积物再悬浮及悬浮泥沙输运机制

Surface sediment resuspension and suspended sediment transportation mechanism in the waters around Miaodao Strait

  • 摘要: 根据实测水文泥沙资料,利用悬浮泥沙沉降公式、泥沙起动流速公式、再悬浮通量与沉降通量公式以及通量机制分解方法,分析了庙岛海峡周边海域的悬浮泥沙时空分布和变化特征,计算了再悬浮通量、沉降通量、单宽悬浮泥沙输运量,探讨了表层沉积物再悬浮和悬浮泥沙运移特征及动力机制。结果表明,悬浮泥沙浓度周期变化与潮流流速周期变化具有较好的相关性,底层悬沙浓度变化对高流速的响应比较明显,表层悬沙浓度变化对低流速响应比较明显;悬浮泥沙单颗粒沉降现象不明显,除庙岛海峡外其他海域较适合悬浮泥沙絮凝沉降,并以中、底层絮凝沉降为主,且表现出自表层至底层絮凝沉降作用逐渐加强趋势;表层沉积物再悬浮对近岸浅水区、庙岛群岛周边海域水体悬浮泥沙浓度的影响显著于其他海域;悬浮泥沙输运整体以平流输运为主,垂向净环流为辅,庙岛海峡南侧向黄海输沙、北侧向渤海输沙,二者同时进行,悬浮泥沙净输运主要由水道向两侧浅滩。

     

    Abstract: Based on the hydrological and sediment measurement data, characteristics of spatiotemporal distributions and variations of suspended sediment concentration and particle size around Miaodao Strait in Bohai Sea were analyzed. By using formulas of suspended sediment settlement, sediment incipient velocity, resuspension flux, and settlement flux, and the flux mechanism decomposition method, the resuspension flux, sedimentation flux, and suspended sediment transport capacity in the study area were calculated. The characteristics and dynamic mechanism of surface sediment resuspension and suspended sediment transport were analyzed. Results reveal a strong relationship between the periodic changes in the suspended sediment concentration and the tidal current velocity. The bottom layer responds obviously to high velocity while the surface layer responds obviously to low velocity. The phenomenon of single particle sedimentation of suspended sediment is not obvious. The hydrodynamic conditions in the sea areas are suitable for flocculation and sedimentation of suspended sediments except for the Miaodao Strait, and are mainly dominated by middle and bottom flocculation and sedimentation. The effect of surface sediment resuspension on the concentration of suspended sediment in the nearshore shallow water area and the sea area around the Miaodao Strait is significantly higher than that in other sea areas. The transport of suspended sediment is mainly advection transport and supplemented by vertical net circulation. In the southern side of Miaodao Strait, sediments are transported to the Yellow Sea, while those on the northern side to the Bohai Sea. The net transport of suspended sediment is mainly from the waterway to the shoals on both sides.

     

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