珠江伶仃洋河口滩槽异变格局下余流结构及其悬沙输移机制研究

The dynamic structure and its variation under variant pattern of shoal and trough driven by strong human activities in the Lingdingyang Estuary of the Pearl River is a frontier scientific issue in the study of estuary evolution and a new challenge for estuary management. The structure of residual currents and its suspended sediment transport mechanism under the variant pattern of shoal and trough have become the new focus of estuarine material transport research. The Lingdingyang Estuary of the Pearl River is selected as the target area in this research. Aiming at complex variations of suspended sediment transport caused by variability of residual current structure and complexity of its driving mechanism in estuaries, three observational vertical lines will be laid to carry out hydrological measurements of high tide in the shoal and trough topography units during flood and dry seasons. The driving mechanism of runoff、 tidal currents、 wind stress and density gradient on the structure of estuarine residual currents and the influence of seasonal variation of salt and fresh water mixing on the structure of estuarine residual currents will be studied by means of numerical simulation sensitivity experiments and analysis of hydrological and sediment observation data. Based on the characteristics of residual current structure and its variation, the analysis of the suspended sediment flux mechanism decomposition will be undertaken to reveal the contribution mechanism of residual current items controlled by the key regulation dynamic factors to the suspended sediment transport under the variant pattern of shoal and trough, and to provide scientific basis for ecological control and environmental protection in the Lingdingyang Estuary of the Pearl River.

强人类活动驱动的珠江伶仃洋河口滩槽异变格局下的动力结构及其变化是河口演变研究的前沿科学问题，是河口治理面临的新挑战，滩槽异变格局下余流结构及其悬沙输移机制已成为河口物质输运研究的新焦点。选取珠江伶仃洋河口为研究靶区，针对河口滩槽异变格局下余流结构多变性及其驱动机制复杂性导致的河口悬沙输移复杂变化问题，在滩槽地貌单元共布设3条观测垂线进行洪枯两季大潮水文测验，采用数值模拟敏感性实验和水文泥沙观测资料分析相结合的方法，研究径流、潮流、风应力和密度梯度对河口余流结构的驱动机制，以及盐淡水混合季节变化对河口余流结构的影响；基于余流结构及其变化，进行悬沙通量机制分解分析，揭示河口滩槽异变格局下受主控动力因子调控的余流项对悬沙输移的贡献机制，并为珠江伶仃洋河口生态治理和环境保护提供科学依据。

河口是陆海物质交换与输运的重要地带，区位独特，环境特殊。针对强人类活动影响下珠江伶仃洋河口动力结构异变及其悬沙输移机制问题，采用数值模拟与现场水文观测相结合的方法，以余流结构变化为切入点，研究伶仃洋不同地貌结构单元潮流、余流的特征与结构，以及悬沙输移机制。研究表明在潮周期内，浅滩和深槽代表点涨落潮历时不等，潮汐不对称现象明显，以洪季最显著。在涨落潮阶段和潮周期内，悬沙浓度平均值基本由表层向底层递增至峰值，浅滩代表点各层水体悬沙浓度普遍高于深槽代表点，且其差异在洪季更为显著。悬沙浓度垂向分布的峰值基本出现在憩流时刻的近底层水体，悬沙浓度垂向分布曲线以斜线型、L型为主。洪、枯季浅滩和深槽测点的总输沙量均向海，且浅滩代表点的输沙量大于深槽代表点。浅滩和深槽代表点各层水体均以向海欧拉余流为主，且洪季余流大于枯季。洪、枯季两测点均以平流输沙项为主，在深槽处以向海欧拉余流输沙为主，在浅滩处则是欧拉余流与斯托克斯余流共同作用，其中洪季深槽处斯托克斯余流输沙向陆。此外，本项目收集了研究区域多个断面的走航观测资料，并在洪季与枯季开展了水文泥沙测验，形成了点面结合的重要数据集。研究成果可为滩槽异变格局下河口地貌动力演变和生态治理等提供科学依据和技术支撑。基于本项目开展的研究，发表相关学术论文5篇（SCI论文3篇，英文EI论文1篇，中文核心期刊论文1篇）；申请受理中国专利9项，其中已授权发明专利3项，已授权实用新型专利1项；项目执行期间培养硕士研究生1名。