| 摘要: |
| 为了研究长江口北槽深水航道的泥沙回淤机制及来源, 通过对长江口北槽深水航道中部南、北导堤两侧坝田区域所采浅钻柱状样的沉积物特征、粒度参数特征、粒度成分和沉积速率特征等的分析,探讨北槽深水航道水动力条件和泥沙沉积环境。结果显示, 柱状样以黏土质粉砂为主, 受径流和潮汐作用, 分选性都较差, 偏态均为正偏, 北导堤和南导堤两侧柱状样的分选系数、偏态和峰态在同一侧相互之间的特征较一致, 且三组分组成接近; 南北导堤异侧之间的粒度特征差异较为明显, 北导堤一侧的平均粒度比南导堤的小, 北导堤坝田附近的柱状样粒级百分比在垂向上波动变化较大, 南导堤则表现的较为单一; 南北导堤的敏感组分主要集中在粒级100 μm部分。结合资料和测年数据, 综合得出,由于北导堤和南导堤的涨落潮不对称, 导致了其粒度特征上的不同; 北槽淤积中的流域供沙逐渐减少,泥沙来源逐渐转变为滩槽交换供沙为主; 北槽受深水航道工程影响巨大, 泥沙沉积过程复杂, 还需深入研究。 |
| 关键词: 长江口 北槽 沉积 柱状样 粒度 |
| DOI：10.11759/hykx20150104002 |
| 分类号: |
| 基金项目:国家自然科学基金项目(41276080, 51320105005); 水利部公益项目(201201070-03) |
|
| Sediment depositional characteristics of North Passage in the Yangtze River Estuary |
|
DENG Zhi-rui, HE Qing, XING Chao-feng, GUO Lei-cheng, WANG Xian-ye
|
|
State Key Laboratory of Estuarine and Coastal Research, East China Normal University
|
| Abstract: |
| Sediment transport and sedimentation in the North Passage in the Yangtze River Estuary were investigated by exploring the hydrodynamic and depositional processes through analyses of sediment core characteristics, grain size parameters, and sedimentation rates. It was observed that the deposited sediment mostly comprised clayey silt, which features poor sorting and a positive skewness due to the significant influence of river–tide interactions. The values of core skewness and kurtosis coefficients indicate consistent characteristics of sediment components at the north jetty and south jetty, respectively. However, the difference between the north side and south side is evident because the mean grain size at the north jetty was smaller than that at the south jetty. Conversely, the vertical grading curve at the north jetty had a larger fluctuation than that that at the south jetty, suggesting a more stable sediment core grain size distribution at the south jetty. Standard deviation of grain size component analysis showed that a 100-micron grain size was the most sensitive component on both sides. In combination with data from both hydrodynamics and isotope dating, it was observed that tidal asymmetry was the primary controlling factor that caused differences in grain size characteristics on both sides[Editor1] of the North Passage. In addition, it was found that the sediment from the riverine side gradually reduces, while the supply from sediment exchange between the channel and floodplain becomes dominant for the sedimentation process. Further study is required as the deep-water channel project has substantial influence on sediment transport in the North Passage. |
| Key words: Yangtze River Estuary North Passage sediment depositional core sediments grain size |
