黄河口海域盐度变化对入海泥沙沉降与固结及侵蚀过程影响

Every year,approximately 8 hundred million tons of sediment discharged into sea from the high-ladern Yellow River, of which 70-80 percent deposits within the estuarine range of 30 km.The decreasing of Yellow River runoff,and the water-sand transfers from upstream reservoir has changed the salinity from spatial and temporal distribution.Our subject will solution this problem,how the changing of salinity of Yellow River delat can act on the sediment deposition-consolidation and the erosion.This project consists of four sub-tasks:give a description on the influence of Yellow River runoff on the distribution of salinity in Yellow River estuary; research on the effect of salinity on the dynamic process of sediment flocculation and settlement;research on the effect of salinity on sediment consolidation process; and the resistance to erosion in different salinity of sea water.This project use the following research methods: adopt the present data to study the changing salinity of Yellow River; through in situ observation combine with physical simulation experiment in laboratory,numerical analysis to study the changing of salinity influence the sediment,the consolidation and the erosion. The research findings will first revealed how the human activities cause the changing of Yellow River runoff,and the engineering properties of estuarine sediment . This can go a step further to the prediction and control of estuarine and coastal geologic hazards.

黄河是高含沙河流，每年携带约8亿吨泥沙入海，其中70-80%沉积在河口附近30余公里海域内。黄河入海径流量的持续减少，及上游水库的调水调沙，影响了黄河口海区盐度场的时空分布规律，使其发生变异。黄河口海域盐度场的变异，将导致黄河口入海泥沙的沉降过程、泥沙沉降后的固结过程、固结后的沉积物的抗侵蚀特征发生怎样变化，是本课题拟解答的科学问题。研究内容包括，黄河口海区盐度场变化规律与影响因素；海水盐度对黄河入海泥沙絮凝沉降过程影响；黄河口海水盐度对沉降泥沙的固结过程影响；不同盐度海水环境下形成的沉积物，其抗侵蚀特性有何差异。研究方法包括，通过已有资料收集分析，研究黄河口盐度变化；通过现场观测，结合实验室物理模拟试验、数值分析，研究盐度对泥沙沉降、沉积物固结及侵蚀特性的影响。研究成果将首次揭示，人类活动引起的黄河入海径流量变化，如何影响河口沉积物工程性质。成果可进一步为黄河三角洲侵蚀灾害防治提供指导。

黄河每年输送上亿吨泥沙入海，其中 80%以上沉积在河口附近的水下三角洲地区。黄河口海域盐度受河流入海的淡水径流与外海高盐度海水共同控制，具有年际变化和季节变化显著的特征。海域盐度的分布差异不仅影响着海洋环流的变化和生态系统的健康程度，同时对黄河口入海泥沙的沉降、固结、侵蚀过程也有着重要影响。本项目围绕黄河口海区盐度场变化规律与影响因素，海水盐度对黄河入海泥沉降、泥沙固结过程的影响，不同盐度海水环境下形成的沉积物，其抗侵蚀特性有何差异，开展了系统的工作。基于现场观测、现场调查、室内外模型试验与数值计算，构建了黄河口地区的复杂盐度场分区；分析了黄河口地区不同盐度沉积环境下的泥沙沉降、固结、侵蚀过程的差异特征；建立了沉积物物理力学性质、固结强度、固结系数、孔隙水压力、临界剪切强度与沉积环境盐度之间的定量关系；并结合双电层理论，揭示了不同沉积环境盐度对于沉积物沉降、固结、侵蚀过程影响的机理。研究成果丰富了现代黄河三角洲沉积动力过程的研究，对黄河三角洲侵蚀灾害防治具有重要的指导意义。