黄河水下三角洲沉积动力分区：过程、机制与沉积效应

This project aims at understanding the temporal-spatial pattern of sediment dynamics of the subaqueous Yellow River Delta and the related impacts on the sedimetary environment. Based on the integrated observations of hydrography, sediment dynamics and sedimentology in the coastal area of the subaqueous delta as well as on the data collection of sediement dynamics, seabed morphology and sedimentary structures, we will compare the difference of sediment dynamic processes between the present river mouth and the abandoned delta lobe in order to examine the temporal-spatial pattern of sediment dynamics of the whole subaqueous delta and to understand the relationship between the sediment dynamics and shift of depo-centers of the subaqueous delta. Subsequently, a three-dimensional model on coastal sediment dynamics will be built up to reproduce the sediment transport process and sedimentation for the abandoned delta lobe in its active period as the numerical simulation will present a contrast with the present situation and with the presently active river mouth. These efforts will illustrate the mechanism that dominates the formation of the spatially vaying sediment processes and ellucidate the impacts on the sedimentary environment of the Yellow River Delta. The project attempts to present the spatial difference of sediment dynamic process driven by different external factors such as the river channel shift and changing sediment flux from the river basin, and to reveal the dominant factors for the morphological evolution. It will improve the scientific understanding of sediment 'source-sink'system of large river delta and thus would be of importance to the decision makers and public for the development and protection of the Yellow River Delta in the future.

本申请项目以黄河三角洲海域沉积动力过程的时空差异为切入点，将三角洲海域整体作为研究对象，考察水下三角洲沉积动力分区及其季节性差异，揭示水下三角洲演化的动力驱动机制。在不同季节和不同时段，采用高分辨率观测仪器，在三角洲近岸和离岸区域开展沉积动力和沉积学综合观测，结合历史观测资料，对比现行河口区域和废弃河口区域的沉积动力过程时空差异，揭示三角洲海域的沉积动力分区及其与水下三角洲沉积中心迁移的关系；建立近海沉积动力三维数值模式，模拟废弃河口行水期沉积物传输过程与沉积过程，并与目前的沉积动力过程和现行河口沉的积动力过程进行对比研究，揭示水下三角洲沉积动力分区的形成机制，阐明沉积动力分区导致的沉积效应。 通过研究，将揭示不同环境因素（河流改道、物质输入变化等）驱动下三角洲沉积动力过程的时空差异，阐明水下三角洲演变的动力机制，丰富大河三角洲"源-汇"过程的研究，为黄河三角洲开发和保护提供重要科学支撑。

本项目以黄河三角洲海域沉积动力过程的时空差异为切入点，将三角洲海域整体作为研究对象，考察水下三角洲沉积动力分区及其季节性差异，揭示水下三角洲演化的动力驱动机制。项目执行期间，在不同季节和不同时段，在三角洲近岸和离岸区域开展了多个沉积动力和沉积学综合观测航次，获得了海域水文泥沙观测数据，结合历史观测资料，将现行河口区域和废弃河口区域的沉积动力过程进行了系统对比，揭示了三角洲海域的沉积动力分区及其与水下三角洲沉积中心迁移的关系；通过百年尺度上沉积记录研究，揭示了三角洲不同区域对河流改道的差异性响应及其机制；利用近海沉积动力三维数值模式，模拟了废弃河口行水期沉积物传输过程与沉积过程，并与目前的沉积动力过程和现行河口沉的积动力过程进行对比研究，揭示了水下三角洲沉积动力分区的形成机制，阐明了沉积动力分区导致的沉积效应。项目共发表论文15篇，其中SCI论文11篇，培养了一批研究生。项目研究揭示了不同环境因素（河流改道、物质输入变化等）驱动下三角洲沉积动力过程的时空差异，阐明了水下三角洲演变的动力机制，丰富了大河三角洲“源-汇”过程的研究，为黄河三角洲开发和保护提供重要科学支撑。