| 摘要: |
| 选用1996年9月5—6日黄河口新口门水文泥沙同步观测资料,采用距离倒数加权插值法(IDW)生成河口泥沙异重流的含沙海水密度、流速和含沙量随时间变化的等值线图。基于此,分析了黄河口泥沙异重流发育形成的时空变化特征,并结合遥感影像和水下地形图进一步探讨了泥沙异重流对河口沉积的影响。研究结果表明,黄河口(新口门)泥沙异重流发育频繁,且其形成时的含沙海水密度与老河口相似;泥沙异重流的空间分布与水下三角洲泥沙堆积体及河口沙嘴的形态存在明显相关,泥沙异重流的存在直接影响河口前缘泥沙的沉积,但对侧缘的影响不大;泥沙异重流形成初期,在低高潮涨潮阶段中的一次较小的涨落潮周期内其形成和消亡过程与潮流的涨落潮周期呈正向对应关系,且在这一时段的涨憩时泥沙异重流的泥沙含量达到最大;流速垂向分布为泥沙异重流形成初期流速小于上层海水流速,且层次分明,随其进一步向深海运动流速呈增大再减小的趋势,至三角洲前缘陡坡段其底层流速大干中上层海水流速。 |
| 关键词: 黄河口，泥沙异重流，河口沉积，时空分布， 海水密度 |
| DOI：10.11693/hyhz200801013013 |
| 分类号: |
| 基金项目:国家自然科学基金，50339050号;国家自然科学基金，40676037号 |
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| 黄河清8出汊河口泥沙异重流特征及其时空分布SPATIAL-TEMPORAL CHANGE OF DENSITY CURRENT AT NEW OUTLET OF THE HUANGHE (YELLOW) RIVER |
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HUANG Hai-Jun1, LIU Yan-Xia1,2, FAN Hui3, YANG Xiao-Yang4
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1.Institute of Oceanology,Chinese Academy of Sciences;2.Graduate School of the Chinese Academy of Sciences;3.Institute for Development Strategy of Science and Technology,Shandong Academy of Sciences;4.Institute of Yellow River Estuary,Yellow River Conservancy Commission of the Ministry of Water Resources
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| Abstract: |
| The dynamics in the Huanghe (Yellow) River estuary have changed greatly since it was artificially diverted in July 1996 near Qing 8. Remote sensing and water depth data of the area surveyed in 1976, 1992, and 2000 were processed. Results show that hyperpycnal plumes were the main form of rapid sedimentation in the delta front. Hydrological measurement showed that critical density of the density current in the area was more than 21kg/m3 different from that of the old estuary before the artificial re-routing. Continuous decrease in precipitation in the river's middle-upper course in recent years resulted in the reduction in water/sediment discharge. Current speed of suspended sediment concentration in spatial and temporal dimensions was measured and analyzed with the Inverse Distance Weighted (IDW) approach. The results show that sediment liquid was very turbulent caused by strong along-shelf currents. The speed of hyperpycnal flows and bottom drag coefficient were high enouth to cause large quadratic dragging of sediment. Rapid deposition of sediments at the mouth by gravity-driven underflows controlled the morphology of sedimentary systems. Changes in thickness show that sedimentation took place mainly in the northern flank of the estuary up to 5.5m, indicating that lyperpycnal plumes developed at the southern side of the main river course and at the delta front of previous Huanghe River course. |
| Key words: Huanghe (Yellow) River estuary, Sediment hyperpycnal plumes, Estuarine sediment, Spatial-temporal distribution, Seawater density |
