福宁湾海域冬季大潮期悬浮泥沙输运特征

Transport characteristics of suspended sediment in Funing Bay during spring tide in winter

  • 摘要: 基于2014年12月在福宁湾附近海域8个站位的同步水文泥沙观测资料,分析了冬季大潮期悬浮泥沙分布以及输运通量的变化规律,并结合理查森数、水体混合所需的势能、潮动力引起的水体势能变化率的计算结果,初步探讨了水体的垂向混合对于悬浮泥沙垂向分布的影响,研究了悬浮泥沙的输运机制。结果表明,从湾内到湾外,温度、盐度总体上呈现递增的趋势;平面上各站位悬浮泥沙浓度由湾内向湾外递减;潮周期内悬浮泥沙浓度变化存在不对称性,总体来说,湾内及湾口处(1#站除外)涨潮阶段悬浮泥沙浓度高,湾外(4#站除外)落潮阶段悬浮泥沙浓度较高。从湾内向湾外,随着水深的增加潮周期内水体的垂向混合逐渐减弱,悬沙浓度的垂向差异逐渐增大。悬浮泥沙输运在湾内及湾口整体表现为向陆输运,在湾外为向海输运。在湾内及湾口处,各分层悬浮泥沙的输运方向大多向陆,且量值较高,而湾外的悬浮泥沙输运方向在垂向上存在差异。由于潮流不对称以及悬浮泥沙的滞后效应引起的潮泵项输运对总的悬浮泥沙通量起主要贡献。

     

    Abstract: Based on the simultaneous field observations at the eight stations near the area of Funing Bay in December of 2014, the variation in suspended sediment distribution pattern and transport flux during the winter spring tide was analyzed. Combined with the calculation results of the Richardson number, the water mixed potential energy, as well as the change rate of water potential energy caused by tidal power, the effects of vertical mixing of water bodies on the distribution of suspended sediment were also discussed, and the transport mechanism of suspended sediments was studied. The results show that the temperature and salinity increase from inside to outside of the bay, and the suspended sediment share the same trend. The concentration of suspended sediment is obviously asymmetrical during a tide cycle, that is, the concentration of suspended sediment is high during the flood tide inside and at the mouth of the bay except the No.1 station, while the concentration is high during the ebb tide outside the bay except the No. 4 station. From inside to outside of the bay, with the increase in water depth, the vertical mixing of water body gradually weakens, and the vertical difference of suspended sediment concentration gradually increases. The transport of suspended sediment is generally transited to the land inside and at the mouth of the bay, while the transport of suspended sediment is transited to the sea outside the bay. The vertical stratified transport direction is mostly landward with a higher value inside and at the mouth of the bay, while the suspended sediment transport direction is different in the vertical direction outside the bay. The tidal pump transport due to the asymmetry of tidal current and the hysteresis effect of suspended sediment plays a major role in the total suspended sediment transport.

     

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