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1.
1976年黄河改道以来三角洲近岸区变化遥感监测 总被引：16，自引：1，他引：16
通过对黄河三角洲沿岸10个河口、潮汐汉道的23景陆地卫星影像高潮线的解译与对比，探讨自1976年黄河改道以来，三角洲岸线的变化特征；同时，利用GIS软件处理1976年和1992年滨海区水深测量数据，并与黄河利津站同期入海沙量进行对照分析。结果表明：1)目前黄河三角洲总体处于侵蚀破坏阶段，侵蚀岸线长相当于淤积岸线的2倍；2)人类活动对三角洲岸线变化的影响不断增强，人工海岸长度大幅度增加，总岸线长度缩短，岸线趋于平直；3)52．6％的黄河入海泥沙堆积于入海口附近，其中92％的泥沙堆积在15m水深线以内，向外迅速减少，20m水深线以外出现侵蚀；4)87％黄河入海泥沙往东、东南方向扩散与沉积，往南、东北方向扩散与沉积的泥沙很少，河口的北、西北方向整体上处于侵蚀状态。海岸侵蚀与河口泥沙的输移密切相关。 相似文献
2.
基于湛江湾口外海图地形资料,采用GIS与动力地貌分析的方法,研究了近50年来湛江湾口外落潮三角洲的冲淤变化特征,对湛江湾口外落潮三角洲的演变机制进行了探讨。湛江口外落潮三角洲体系包括口外东北浅滩、西南边滩及口门通道深槽。近50年来,东北浅滩东缘及滩顶出现了侵蚀后退,浅滩西缘和南缘呈淤积趋势,东北浅滩整体有西移南扩趋势;西南边滩有不同程度的侵蚀后退;口门通道深槽有所淤积。湛江湾口外落潮三角洲侵蚀与沿岸泥沙供给不足及人类活动影响有关,口门通道深槽淤积除与落潮三角洲侵蚀泥沙向西搬运有关外,还可能与湛江湾内围垦导致口门通道潮汐动力减弱有关。航道北侧东北浅滩变化对航道回淤的可能影响值得关注。 相似文献
3.
本文通过实测资料，分析了黄河清水沟流路入海泥沙淤积在三角洲陆上和滨海以及漂向外海的泥沙分配，统计了三角洲淤积造陆沿岸线的淤积延伸宽度以及泥沙在滨海水下的淤积范围，并对潮流和余流引起的泥沙扩散进行了分析。 相似文献
4.
黄河水下三角洲沉积物输运及海底冲淤研究 总被引：2，自引：0，他引：2
根据黄河水下三角洲的特点,建立了一个垂直平均二维沉积物输运数学模型,结合潮流和沉积物资料,模拟研究了沉积物输运机制和海底冲淤演变过程。模拟结果表明,垂直河口射流的潮流决定了本区沉积物净输运的总体格局,风应力对悬浮泥沙和推移质泥沙运动也起到重要作用。潮流底应力和活动层厚度分布表明,黄河口门和埕岛油田附近海域是潮流底应力和活动层厚度高值区,为沉积物活跃区,海底稳定性弱,易于侵蚀再搬运。冲淤计算表明,埕岛油田附近海域为冲刷中心区;现在河口水下三角洲在断流时为冲刷区,正常行河时则转为淤积区。 相似文献
5.
对黄河口30多年来的叶瓣演变过程进行了详细研究。利用遥感假彩色合成解译历年岸线和流路河道变化,利用1976—2005多年的水深数据,定量分析了清水沟叶瓣水下三角洲堆积体不同时段的冲淤变化过程。将水下三角洲堆积体的演变过程划分为4个阶段,即多淤积中心阶段→单一稳定淤积阶段→缓慢淤积阶段→淤积—侵蚀同时发生阶段,证明黄河口三角洲堆积体演变过程对流路演化的阶段性有很好的响应关系。同时对清水沟水下三角洲演化的影响因素进行了分析。 相似文献
6.
本文基于近50 a来的辽河口海域的水下地形资料,采用GIS技术手段研究了辽河口水下三角洲的演变特征。研究结果表明:近50 a来辽河水下三角洲外缘(蛤蜊岗子滩西缘和南缘、西滩西缘和南缘)出现较大幅度的侵蚀后退;蛤蜊岗子滩东缘淤积外移,南部滩尾东部有北移东偏趋势;近岸浅滩由淤涨变为基本稳定,局部有所侵蚀后退;受蛤蜊岗子滩向东淤进的影响,蛤蜊岗子滩东侧深槽有所缩窄;蛤蜊岗子滩和西滩之间深槽水域出现拓宽变浅的变化趋势。流域来水来沙减少是近年来辽河口水下三角洲外缘侵蚀后退的主要原因,外缘侵蚀泥沙在波流作用下向河口搬运是蛤蜊岗子滩东侧淤积、深槽缩窄的主要原因,近岸边滩人工围垦对水下三角洲演变的影响值得关注。 相似文献
7.
以2013年莱州三山岛黄金海岸海滩剖面等实测资料为基础,结合海图和遥感影像等历史资料,利用数值模拟、泥沙起动流速计算和沿岸输沙计算等方法对研究区的冲淤特征进行了研究,并在此基础上初步探讨了影响冲淤演变的主要因素。结果表明,2009—2012年期间王河口至黄金海岸东端之间岸线保持平衡,黄金海岸岸线全线后退,处于侵蚀状态,黄金海岸西段至刁龙嘴之间岸段由于养殖池建设部分岸线向海推进;1984—2004年期间研究区整体处于侵蚀状态,等深线呈不同程度后退;2004—2013年期间研究区整体呈侵蚀状态,近岸海域侵蚀量在0.5~1m之间,7m等深线以深海域呈微淤积状态,淤积量0.5m;人类活动是影响研究区近期冲淤变化的根本因素。 相似文献
8.
河口三角洲区域地质环境脆弱，对环境变化响应敏感，三角洲港口冲淤演变受工程结构影响较大。黄河三角洲的东营港区域以粉砂质海岸为主，区域内泥沙运移活跃，此类区域港口建设的关键问题在于工程结构导致的海床冲淤变化。通过东营港建港以来实测水深数据构建水下地形数字高程模型(DEM)，并结合水动力数值模拟，探讨了东营港冲淤演变过程和工程影响。结果表明，由于波浪和潮流导致的海底地形变化，东营港近岸海域的冲淤演变形势已从单一侵蚀转变到近岸侵蚀、离岸淤积的新情势；工程结构影响局地潮流流速和流向，口门处出现高速横流，最大流速可达0.7 m/s；高流速导致北防波堤的堤头位置出现直径约1 km的冲刷坑；工程结构的遮蔽区有促淤效应，遮蔽区大小与潮流流向、工程结构-岸线夹角有关，但在波浪、余流的作用下，2007-2015年工程结构遮蔽区依旧存在0.5 m以上的侵蚀。持续的侵蚀作用使海域防波堤和海堤的不稳定性加剧，迫切需要加强检测与防护。 相似文献
9.
文章利用1985、1995、2005、2009年的Landsat卫星遥感影像和2015年的GF-1卫星遥感影像,分析近30年来图们江口海岸线的变化特征。结果表明:近30年来图们江口海岸线长度整体呈增长态势,累积增加0.66km,主要由人类开发活动及泥沙堆积等引起;人工岸线比例增大,但1985—1995年因河流改道致使岸线减少3.8km。1985—2005年海岸带淤积面积大于侵蚀面积,其中河流改道使1995—2005年淤积面积达到4.522 7km2;2005—2015年侵蚀面积大于淤积面积;2005—2009年径流量减少使侵蚀面积达到4.203 7km2。河口处的岸线迁移变化最大,其他地区较稳定。 相似文献
10.
收集了1976～2000年现代黄河三角洲地区的Landsat影像,采用平均高潮线法解译出25 a来的海岸线,分析了现代黄河三角洲地区的岸线长度变化,迁移特征以及河口三角洲的时空发育规律.结果表明:现代黄河三角洲地区岸线变迁可以分为三部分:北部、中部和南部,其中中部是变化最剧烈的岸段.根据河道摆动规律和三角洲的延伸方向,现代黄河三角洲的发育可以分为四个阶段:填湾阶段(1976～1981年)、中部突出阶段(1981～1983年)、东南方向突出和鸟嘴状沙嘴形成阶段(1983～1996年)、河流改道和新沙嘴形成阶段(1996～2000年),四个阶段共淤积造陆378.2 km2,侵蚀49.3 km2,净增长328.9 km2.此研究结果对于认识现代黄河三角洲的时空发育演变具有一定的意义. 相似文献
11.
Late Holocene chronology,origin, and evolution of the St. Bernard Shoals,Northern Gulf of Mexico,USA
Several shore-parallel marine sand bodies lie on the Louisiana continental shelf. They are Trinity Shoal, Ship Shoal, Outer
Shoal, and the St. Bernard Shoals. These shoals mark the submerged positions of ancient shorelines associated with abandoned
deltas. Three of these shoals are single elongate deposits. The fourth shoal, the St. Bernard Shoals, consists of a group
of discrete sand bodies ranging in size from 44 to 0.05 km2, 25 km southeast of the Chandeleur Islands in 15–18 m of water. The St. Bernard Shoals are stratigraphically above the St.
Bernard delta complex, which was active 2,500–1,800 years b.p. Understanding the evolution of the St. Bernard Shoals is necessary to reconstruct the Holocene chronology of the St. Bernard
delta complex and the eastern Louisiana continental shelf. For this study, 47 vibracores and 400 km of shallow seismic reflection
data collected in 1987 across the Louisiana shelf were analyzed. In June 2008, 384 km of higher-resolution seismic reflection
data were acquired across the study area and appended to the preexisting datasets. Vibracores were integrated with seismic
profiles to identify facies and their regional distribution. Our results demonstrate that the deltaic package stratigraphically
below the St. Bernard Shoals is chronologically younger than the northern distributaries, but derived from the same trunk
distributary channel (Bayou la Loutre). The river eventually bypassed the northern distributaries, and began to deposit sediment
further onto the continental shelf. After abandonment, the overextended delta lobe was rapidly transgressed, creating a transgressive
shoreline that eventually coalesced with earlier shorelines in the region to form the Chandeleur Islands. The St. Bernard
Shoals formed by the reworking of the relict distributary deposits exposed on the inner to mid shelf during and subsequent
to shoreface ravinement. 相似文献
12.
现代黄河三角洲的泥沙运移是河-海动力相互作用下的泥沙分配和再分配结果。现行水口门区岸滩和水下岸坡仍以不大的速率向海淤进,三角洲西段和南段沿岸基本处于动态平衡状态,三角洲中段广大岸段大都处于不同程度的冲刷蚀退态势。冲刷蚀退已严重地恶化了黄河现代三角洲的发育功能和三角洲经济开发环境,对油田的滩海工程和海上设施造成了严重威胁。 相似文献
13.
14.
Sediment source and transport trends are influenced by various hydrodynamic factors, and thus play important roles in sedimentary evolution and coastal stability. To examine sediment transport trends around the abandoned Yellow River delta promontory and its erosion mechanism, we employ empirical orthogonal function (EOF) analysis to study sedimentary characteristics and transport trends of the abandoned Yellow River delta in northern Jiangsu Province, China. The results showed that: (1) the main sediment source in the abandoned Yellow River delta is the submarine coastal slope and both sides of the abandoned Yellow River Delta; (2) the main hydrodynamics controlling sediment transport is the current that runs along the shore, coupled with waves, especially southward currents; (3) the sediment of the study area was redistributed under hydrodynamics; coarse sediments were eroded and broadly transported to the south. Therefore, it is concluded that the sediment sources and transport have important influence on coastal evolution: the sediment source area shows mass loss of deposits and erosion; deposits in the submarine coastal slope provide the source and were continuously eroded to provide materials to other places as a sediment source. 相似文献
15.
开展枯季河口悬沙输运机理研究对于揭示弱径流条件下的陆海相互作用、河口季节性冲淤和水沙关系等具有重要的科学意义.本文根据2018年12月18-25日长江口南槽3个站位连续13个潮周期的同步流速、流向和悬沙浓度等观测资料,运用通量机制分解法研究了各输沙项的特征、贡献和输运机理.结果 表明,从小潮至大潮流速和悬沙浓度不断增加,由南槽上部至下部流速和悬沙浓度逐渐降低.观测期间平均流速与平均悬沙浓度存在明显的正线性关系,但受底质空间差异影响,悬沙浓度对流速的响应强度存在显著的空间变化.枯季期间南槽存在着中上部向陆净输沙、下部向海净输沙的空间输运格局.平流输沙和潮泵输沙是影响和控制净输沙的关键因素,二者的强度和贡献存在明显的潮周期变化和空间变化,垂向环流输沙的强度很弱,对净输沙贡献很小.南槽涨落潮输沙不对称现象明显,流速、悬沙浓度和历时都具有一定的涨落潮不对称性,这些不对称现象共同调节和控制着潮周期净输沙强度和方向的时空变化. 相似文献
16.
冰后期最大海侵以来长江,钱塘江河口湾发育过程的沉积动力学研究 总被引：2，自引：0，他引：2
朱玉荣 《海洋地质与第四纪地质》2000,20(2):1-6
利用二进流数学模型对冰后期最大海侵以来５期古岸线与现在岸线条件下古长江河口湾、古钱塘江河口湾及其邻近海域的主要水动力Ｍ２潮流场进行了数值模拟;在此基础上,分别计算了进入不同时期潮流场的７种粒径泥沙的潮平均单宽悬移输沙率与扒移输沙率及其相应的输沙率散度,据此得出不同粒径泥沙在当时潮流场中的悬移与推移输过趋势,划分了海 淤积区与冲刷区 同时期的潮流场作用下,长江入海泥沙除最大限度地沉积在古长江河口湾（ 相似文献
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18.
Relationship between suspended sediments from the Changjiang Estuary and the evolution of the embayed muddy coast of Zhejiang Province 总被引：2，自引：1，他引：2
South of Hangzhou Bay, Zhejiang Province, exhibits an embayed muddy coastline, with the muddy beaches of embayments extending continuously seaward.The source of sediments on this coast presents an interesting problem to marine geologists and geomorphologists .The total annual load of sediments from the rivers of Zhejiang is only 12×106t.These materials affect only the area near the river mouths. The paper showed that the sediment along the coast of Zhejiang mainly comes from the Changjiang Estuary through analysing the time and space variations of suspended sediment, the features of sediment and the sedimentary transport.The Changjiang River is the largest river system in China, its sediment to the sea amounting to 468×106t. The sediment during summer transports mainly eastward, and is affected by the water body with high temperature, salinity and transparency; the winter season is the period with high sediment concentration. The sediment of the Changjiang Estuary transports together with the longshor 相似文献
19.
David J. Mallinson Curtis W. Smith Stephen J. Culver Stanley R. Riggs Dorothea Ames 《Estuarine, Coastal and Shelf Science》2010
Nearly 200 km of high-resolution ground penetrating radar (GPR) data were acquired along the Outer Banks barrier island system of North Carolina, USA. GPR data combined with lithofacies and biofacies data reveal multiple depositional facies including inlet channel, flood-tide delta, overwash, peat and inner shelf. Previously undocumented paleo-inlet channels constitute a significant portion of the shallow geologic framework between Oregon Inlet and Cape Hatteras. GPR data reveal the complex stratigraphy associated with multiple sequences of cut-and-fill within inlet channels. Two types of paleochannels (non-migrating and migrating) were classified based on geometry and fill-patterns. Sediments and foraminifera collected from vibracores were correlated to GPR data to define the regional shallow stratigraphic framework. Channel-fill facies are characterized by clinoform packages, sometimes bounded by erosional surfaces, indicating variable sediment transport directions from the ocean and sound sides. Channels are incised into older flood-tide delta deposits corresponding to older inlet activity when barriers existed further seaward. Flood-tide delta deposits are capped with marsh peat and overwash units. Migrating inlet facies occur under the widest portions of the island, whereas narrow portions of the island are underlain by the non-migrating inlet facies or flood-tide delta/overwash facies. This geologic/geomorphic relationship is attributed to the successional stage of island evolution during transgression, and sediment transport processes associated with the different inlet types. The radar facies, lithofacies, and biofacies provide a comprehensive dataset that will permit more precise identification of barrier island facies in the geologic record. 相似文献
20.
Sediment supply and pre-existing shoreline morphology are crucial factors in controlling coastal changes due to sea-level rise. Using examples from both southeast and northeast Ireland, it can be shown that sea-level change may trigger a sequence of events which leads to both static and dynamic shoreline equilibrium. Cliff erosion and longshore sediment movement in east Co. Wexford has led to injection of sediment onto the shelf, and the growth, under both wave and tide regimes, of linear offshore shoals. These shoals now control the pattern of shoreline erosion and provide a template for possible stepwise evolution of the coast under any future sea-level rise. In contrast, the nearby coast of south Co. Wexford comprises a series of coarse clastic barriers moving monotonously onshore, via overwash processes. Here the behavior of the barrier is conditioned by the antecedent morphology of both the beach face and stream outlet bedforms. Finally, the rock platform coast of Co. Antrim presents a far more resistant shoreline to incident marine processes, yet even here there is strong evidence of present process control over so-called ‘raised’ platforms and embayments. It is concluded that coastal sediment supply and dynamics, together with coastal morphology and its interaction with waves, present a far more complex variety of sea-level indicators than is normally acknowledged. 相似文献