| 摘要: |
| 利用近20年来长江河口所观测的地形、水文、悬沙和河床沉积物资料，着重对1988、1989、1996和1997年最新观测资料进行计算分析。结果表明，长江河口航道拦门沙河段来水来沙量大，潮流作用强，潮波变形明显，水流挟沙力强。该河段潮流速随时间和空间变化，又处在盐淡水交换地带，流域和海域来沙在此河床时淤时冲，悬沙与床沙交换频繁，表现在涨急、落急时将河床淤积层泥沙再次起动悬浮，憩流时又重新淤积河床，在一个潮周期中含沙量出现2高2低。近河床若存在一层浮泥时，在下击和上升流的作用下，在一个潮周期中河床泥沙被3次或4次再悬浮。在大潮期河床泥沙普遍扬起，小潮汛期间再次淤积，河床冲淤层变幅为0.2–0.4m,左右（南槽）。洪季来沙多，使河床普遍发生淤积；而枯季来沙少，河床发生自然冲刷，多年平均冲淤层变幅为0.6m左右，部分河床可达1.4–2.4m。 |
| 关键词: 长江河口 泥沙运动 泥沙再悬浮 河口拦门沙 |
| DOI：10.11693/hyhz200001016016 |
| 分类号: |
| 基金项目:“九五”国家重点科技攻关项目“典型河口冲淤灾害预测技术研究”专题研究成果之一，96－922－03－02号 |
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| A STUDY ON SEDIMENT DEPOSITION AND RESUSPENSION IN THE MOUTH BAR AREA OF THE CHANGJIANG RIVER ESTUARY |
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LI Jiu-fa, HE Qing, ZHANG Chen
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State Key Lab. of Estuarine and Coastal Research, East China Normal University, Shanghai 200062
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| Abstract: |
| The mouth bar area in the Changjiang River estuary is well-known for its large water and sediment discharges, strong tidal action, significant tidal wave reduction and big sediment carrying capacity. The velocity of tidal currents changes both with time and space and the area of the mouth bar is the major place for forming the density current of the salt and fresh water. There is an exchange between suspended load and bed load, causing frequently erosion and deposition at the same time. Based on a vast amount of hydrology, sediment and topography data since the 1970s, sediment erosion, deposition and resuspension in the Changjiang River estuary were briefly discussed in this paper. It wad found that there were sediment resuspension during the maximum velocity in the ebb and floodtides and sediment deposition between the ebb and floodtides. Generally, two peaks and two valleys of sediment concentration occurred during a tidal period. Existence of low unit weight sediments on surface also causes resuspension during turning time of flood and ebb which results in 3–4 concentration peaks within a tidal cycle. The erosion and deposition depth was found to be 0.2m between the spring and neap tides. Sediment resuspension happened in flood seasons and sediment deposition happened in dry seasons with an average depth of 0.6m. |
| Key words: The Changjiang River estuary, Sediment transport, Sediment resuspension, River mouth bar |
