江苏北部废黄河口水下三角洲稳定性和深水港建设

废黄河口三角洲的演化主要表现为水下三角洲大面积的冲蚀和三角洲海岸线的夷平,形成了由—10m以深的平坦悔床、—5m～—10m问的水下斜坡和—5m以浅的近岸浅滩三个地貌单元构成的地形格局。—10m～—15m水下平台稳定,略有冲刷;而水下斜坡随着往复性潮流长轴与斜坡走向逐渐趋于一致,潮流侧向侵蚀弱化;近岸浅滩则表现为人工护岸条件下的有限下切。这为深水港口的建设提供了良好的近岸水深条件和相对稳定的水陆域环境。     

废黄河三角洲的演变*

本文主要根据历史文献,论述1194～1855年的古黄河口泥沙堆积形式、速率及其沉积特点,并探讨了废黄河三角洲形成机理和类型,以及尾闾变迁对下游河道的影响。认为在黄河南流夺准入黄海过程中,河口和三角洲发育具有明显的阶段性;前、后两期形成不同类型的三角洲,前期为径流一潮汐型,后期转化为径流一波浪型;后期河口迅速延伸,河口基准面相对抬升所引起的溯源淤积可达河南境内。     

黄河三角洲利津超级叶瓣时空范围的再认识

黄河三角洲是世界著名的河流三角洲之一。自有学者首次系统地提出黄河三角洲全新世10期超级叶瓣的时空分布范围后,这一观点近30年来未见明显的改进。借助渤海湾南岸研究区获得的4个20～30 m钻孔地层资料和相应的AMS14C测年数据,以及前人部分钻孔的研究成果,本文对黄河三角洲利津超级叶瓣的沉积演化框架和时空分布特征进行了重新厘定:研究区全新世沉积环境由早期的河道和泛滥平原沉积,逐渐向海侵过程中盐沼、潮坪和浅海相演化。海平面上升速率减缓之后三角洲开始发育并逐步成陆,直至最后被陆相沉积所覆盖。黄河下游古河道在9000-8000 cal a BP左右可能在黄骅南部入海;大约8000 cal a BP之后,黄河主河道南迁到滨州—惠民一带,并在7000-5500 cal a BP之间发育利津超级叶瓣;利津超级叶瓣的北界可能在马山子和阳信一界,而南界在郭井子和弥河之间;约5500 cal a BP之后,黄河下游古河道可能重新过黄骅入海,于5500-3500 cal a BP左右形成黄骅超级叶瓣;约3500 cal a BP之后,黄河古河道北迁至天津,直至～700 BC左右主流河道入海口再次南迁至河北岐口附近。     

黄河口泥沙淤积估算问题和方法——以钓口河亚三角洲为例

以往在黄河三角洲沉积量的估算中,对沉积物干容重和计算边界等问题不够重视,导致计算结果存在明显出入。本项研究通过广泛收集资料和大量采样分析得到了多种沉积环境下沉积物干容重的计算模型,结合三角洲沉积结构分析和利用地形测量数据,计算了黄河口钓口河流路时期亚三角洲不同时期的沉积量。其中1965年至1974年间钓口河亚三角洲前缘坡脚以内的总淤积量为71.0亿t。其平均干容重为1.36g/cm³。这一干容重用于估算其它亚三角洲沉积量不会造成明显误差。认为忽略三角洲下松软沉积层的压实沉降、三角洲平原相和前缘相中粘性土与非粘性土干容重的差别以及来沙量的测量误差对计算结果影响较小。     

现代黄河三角洲叶瓣的划分和识别

黄河分流河道摆动频繁,自1855年以来形成了8个三角洲叶瓣。1904-1929年的三角洲沉积物划归一个叶瓣较为合适。1934-1938年和1947-1964年也应该划归一个叶瓣。叶瓣活动时间短,平均活动时间只有16年。单个叶瓣形成的沉积物厚度有限。一个钻孔剖面上的三角洲沉积物常常分层于数个叶瓣。叶瓣废弃后改造时间短,还没有形成较粗的改造,沉积物便被新的叶瓣所覆盖。两个叶瓣的界线不很清楚。但根据沉积结构和构造,微体化石,²¹⁰pb测年方法,土壤层以及历史记录,可以识别出不同的叶瓣。     

Evolution of sedimentary environments of the middle Jiangsu coast, South Yellow Sea since late MIS 3

An evolutionary model of sedimentary environments since late Marine Isotope Stage 3 （late MIS 3, i.e., ca. 39 cal ka BP） along the middle Jiangsu coast is presented based upon a reinterpretation of core 07SR01, new correlations between adjacent published cores, and shallow seismic profiles recovered in the Xiyang tidal channel and adjacent northern sea areas. Geomorphology, sedimentology, radiocarbon dating and seismic and sequence stratigraphy are combined to confirm that environmental changes since late MIS 3 in the study area were controlled primarily by sea-level fluctuations, sediment discharge of paleo-rivers into the South Yellow Sea （SYS）, and minor tectonic subsidence, all of which impacted the progression of regional geomorphic and sedimentary environments （Le., coastal barrier island freshwater lacustrine swamp, river floodplain, coastal marsh, tidal sand ridge, and tidal channel）. This resulted in the formation of a fifth-order sequence stratigraphy, comprised of the parasequence of the late stage of the last interstadial （Para-Sq2）, including the highstand and forced regressive wedge system tracts （HST and FRWST）, and the parasequence of the postglacial period （Para-Sql）, including the transgressive and highstand system tracts （TST and HST）. The tidal sand ridges likely began to develop during the postglacial transgression as sea-level rise covered the middle Jiangsu coast at ca. 9.0 cal ka BP. These initially submerged tidal sand ridges were constantly migrating until the southward migration of the Yellow River mouth to the northern Jiangsu coast during AD 1128 to 1855. The paleo-Xiyang tidal channel that was determined by the paleo-tidal current field and significantly different from the modern one, was in existence during the Holocene transgressive maxima and lasted until AD 1128. Following the capture of the Huaihe River in AD 1128 by the Yellow River, the paleo-Xiyang tidal channel was infilled with a large amount of river-derived sediments from AD 1128 to 1855, causing the emergence of some of the previously submerged tidal sand ridges. From AD 1855 to the present, the infilled paleo-Xiyang tidal channel has undergone scouring, resulting in its modern form. The modern Xiyang tidal channel continues to widen and deepen, due both to strong tidal current scouring and anthropogenic activities.     

黄河三角洲岸线及现行河口区水下地形演变

根据实测的岸线和水深数据,利用Surfer 和Mapinfo 等软件进行数据处理,结合不同阶段利津站输沙量,分析了黄河三角洲岸线及现行河口区水下地形演变。结果表明:1953-2000年,68%左右的入海泥沙淤积在口门和滨海区。由于入海流路变迁,不同岸段的岸线变化具有各自的特征。刁口河流路以西岸线基本稳定;刁口河流路以东—孤东油田以北岸线经历先淤后冲,属于强侵蚀岸段,但在防潮大堤的保护下得到人为控制下的稳定;清水沟流路形成的岸线整体向海淤进,但清8 出汊后,清水沟老河口沙嘴南侧出现侵蚀。1976-1996 年,现行河口(清水沟流路) 水下地形总体上表现为淤积,顶坡段变缓,前坡段变陡。1996-2005 年,清水沟老河口水下地形顶坡段和前坡段发生侵蚀,底坡段呈现淤积;出汊新河口水下地形继续淤积,但程度和范围都比1976-1996 年的小。孤东油田近岸侵蚀加剧。     

黄河口不同粒度泥沙沉积与扩散分析

本文采集和收集大量黄河三角洲沉积物剖面和钻孔泥沙粒度资料以及黄河口来沙粒度组成数据,定量研究了黄河口泥沙的沉积与扩散特征.结果 显示黄河口来沙以粉砂为主,黏土次之,砂最少,年均中值粒径无长期变化趋势.黄河三角洲平原相泥沙与来沙的黏土、粉砂和砂含量无显著差异;前缘相泥沙比来沙的黏土含量较低,砂含量较高;前三角洲相泥沙比来...     

东江三角洲地貌特征

本文应用地貌学、年代学、沉积学、历史地理学等方法,讨论了东江三角洲的范围,分析了周边地貌和三角洲地貌的特征,研究了构造、气候、河流、海洋诸因素对地貌发育的影响,提出了地貌发育过程的5个阶段的新看法。     

黄河三角洲造陆过程中的陆域水沙临界条件研究

黄河三角洲发育是河口区河流动力及陆域物质通量与海洋动力及海域物质通量相互作用的产物 ,三角洲造陆速率取决于上述两方面的对比关系。当上述两方面处于平衡时 ,三角洲造陆处于临界状态 ,即净造陆速率为零 ,与之相联系的入海泥沙量和径流量可视为黄河三角洲造陆过程的临界水沙条件。运用经验统计方法估算出 :当入海年沙量Qs为 2 78亿t/a、入海年水量Qw为 76 7亿m3时 ,或者当关系式 3 1934Qs+ 0 0 85 6Qw=17 94得到满足时 ,黄河三角洲造陆过程处于临界平衡状态。在黄河流域的环境管理中 ,应将上述两项临界值作为约束条件。黄河流域生态用水量的内涵应予以扩展 ,维持三角洲造陆平衡所必须的入海径流量 ,应作为黄河流域的生态用水量。     

A Sediment Budget of The Lower Yellow River, China, Over The Period from 1855 to 1968

This study investigates the sediment fluxes through the Yellow River sediment routing system, which are among the largest in the world, by constructing a sediment budget of the system over the period from 1855 to 1968. The framework of the sediment budget includes four functional units with the upper and middle reaches of the river as the sediment source and its lower reaches, its delta, and the deep sea as the sediment sinks. Sediment yield from the source and amounts of deposition in the lower Yellow River and the modern Yellow River delta were estimated for completing the sediment budget. The sediment budget produced for the period from 1855 to 1968 was characterized by a sediment input of 1.837 × 10¹¹ tonnes and a distribution of the sediment between the lower Yellow River, the delta, and the deep sea of 64%, 33%, and 3%, respectively. The details of the sediment budget show that the importance of sedimentation in the lower Yellow River changed greatly with variations in the condition of the dykes and other human activities. A comparison of the sediment budgets of the delta for different timescales shows that the proportion of sediment dispersed to the deep sea decreases as the timescale over which the sediment fluxes are investigated increases.