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11.
Haosheng Huang Changsheng Chen Jackson O. Blanton Francisco A. Andrade 《Estuarine, Coastal and Shelf Science》2008
The Okatee River, South Carolina is characterized by a narrow tidal channel and an extensive area of intertidal salt marshes. Current measurements in the upstream portion Okatee Creek show that tidal flow features an asymmetric pattern: ebb current is stronger than flood current. The ebb dominance is mainly caused by deformation of the dominant astronomical tidal constituent M2. An unstructured grid, finite volume coastal ocean model (FVCOM) with wet-dry point treatment method is applied to examine physical mechanisms of M4 overtide generation. Model experiments show that mean absolute amplitude and phase errors are 3.1 cm and 1.7° for M2 elevation, 2.4 cm s−1 and 0.8° for M2 current major axis, 2.1 cm and 1.8° for M4 elevation, and 2.1 cm s−1 and 24.6° for M4 current major axis. The overall pattern of tidal asymmetry is qualitatively reproduced. Various sensitivity experiments suggest that the generation of M4 overtide is a result of nonlinear interaction of tidal currents with irregular creek geometry and bottom topography. Consistent with the classical view, the large volume of intertidal water storage is the major reason for ebb dominance in the creek. However, the zero-inertia assumption (i.e., negligible advective terms) is probably not valid for the entire tidal cycle. Besides the pressure gradient force and the bottom friction force, terms related to lateral shear of the along-estuary velocity (i.e., advective inertia and horizontal eddy viscosity) may also contribute in horizontal momentum balance. Exclusion of the flooding-draining processes over the intertidal zone will severely underestimate tidal currents in the river channel and make the tidal asymmetry less prominent. 相似文献
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曹妃甸老龙沟动力地貌体系及演化 总被引：3，自引：0，他引：3
老龙沟为典型沙坝-泻湖型潮汐汊道,潮汐汊道地貌结构完整.老龙沟口门处潮流动力最强,发育-20m的深槽.口门内涨潮流三角洲上发育完整的多级水道体系.口门外落潮三角洲止于-11 m水深处.以突起的末端坝为地形标志,落潮主水道偏于落潮三角洲东侧发育,落潮三角洲西侧发育宽缓冲流平台.落潮主水道以落潮流为优势,冲流平台上潮流动力... 相似文献
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青岛近海潮流沉积体系 总被引：2，自引：1，他引：2
通过分析钻孔和浅地层剖面资料,研究了胶州湾及青岛前海潮流沉积体系。该体系包括大沽河-洋河潮控三角洲和与狭口海湾密切相关的涨、落潮流三角洲,潮流作用在各三角洲的形成过程中为主要的沉积动力。前者发育在湾西侧,形成了河口沙坝和分流间湾等沉积相;后者分布在湾口两侧,以潮道和潮流沙脊为主要特征。根据对各沉积相特征的分析,认为潮流沉积体系的演化已整体趋于稳定。 相似文献
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Application of neural network and MODIS 250m imagery for estimating suspended sediments concentration in Hangzhou Bay,China 总被引：1，自引：0，他引：1
Suspended sediments concentration (SSC) in surface water derived from bottom sediment resuspension or discharge of sediment-laden
rivers is an important indication of coastal water quality and changes rapidly in high-energy coastal area. Since artificial
neural networks (ANN) had been proven successful in modeling a variety of geophysical transfer functions, an ANN model to
simulate the relationship between surface water SSC and satellite-received radiances was employed. In situ SSC measurements
from the Hangzhou Bay and the Moderate-resolution Imaging Spectroradiometer (MODIS) 250 m daily products were adopted in this
study. Significant correlations were observed between in situ measurements and band 1–2 reflectance values of MODIS images,
respectively. Results indicated that application of ANN model with one hidden layer appeared to yield superior simulation
performance (r
2 = 0.98; n = 25) compared with regression analysis method. The RMSE for the ANN model was less than 10%, whereas the RMSE for the regression
analysis was more than 25%. Results also showed that different tidal situations affect the model simulation results to some
extent. The SSC of surface water in Hangzhou Bay is high and changes rapidly due to tidal flood and ebb during a tidal cycle.
The combined utilization of Terra and Aqua MODIS data can capture the tidal cycle induced dynamic of surface water SSC. This
study demonstrated that MODIS 250 m daily products and ANN model are useful for monitoring surface SSC dynamic within high-energy
coastal water environments. 相似文献
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胶东半岛南部典型海湾地貌过程对滩涂养殖的响应 总被引：2，自引：2，他引：0
应用3S技术和海湾涨/落潮不对称原理,研究了最近40年来胶东半岛南部四个典型潮汐汊道海湾的动力地貌演变,分析了大面积修建养殖池对海湾地貌过程的影响。结果表明,最近30年来4个海湾的海岸地貌类型面积、空间分布格局、地貌类型转换、地貌结构和地貌冲淤状态发生了显著改变。在大面积养殖池被围建以前的1960s年代末到1980s年代初,丁字湾处于涨潮不对称状态但不对称程度增高,乳山湾、五垒岛湾和靖海湾也处于涨潮不对称状态但不对称程度在降低。最近30年来的大面积滩涂养殖池修建,使丁字湾由不断增强的涨潮不对称向落潮不对称状态逆转,使五垒岛湾、靖海湾由涨潮不对称向落潮不对称状态的转化提前,使乳山湾由涨潮不对称向落潮不对称状态的转化延缓。 相似文献
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In this study, the artificial opening of a new tidal inlet in an existing multiple inlet system is shown to significantly modify the adjacent nearshore and backbarrier morphology, as well as both updrift and downdrift shorelines. The study focuses on the dominant Faro‐Olhão and Armona inlets in the Ria Formosa barrier island system of southern Portugal. The equilibrium state and future evolution of the system are inferred using a range of morphological and hydrodynamic indicators, including the evolution of the inlet cross‐section, changes in tidal prism, and changes in the dimensions (length and area) of barrier islands. The results reveal how the morphology of an interconnected two‐inlet bay system and the adjacent coastlines has evolved following the artificial opening and stabilization of Faro‐Olhão inlet since 1929. A clear relationship between barrier island size, inlet cross‐section/width, and tidal prism is demonstrated. Decadal time‐scale changes in the tidal prism of the two interconnected inlets are shown to be the main mechanism responsible for morphological change, and have resulted in the remobilization of ebb‐tidal delta sediments deposited during previous hydraulic configurations. These changes, in turn, have contributed to a narrowing of Armona inlet and an increase in the size of Culatra Island. The work highlights the importance of ebb‐tidal deltas both as sand reservoirs and as conduits through which sand exchange between estuaries or lagoons and the open coast is regulated. It also shows the pivotal role of ebb‐tidal deltas in trapping longshore‐transported sediment and releasing it again during periods of increased wave activity. The findings have implications regarding the accurate assessment of the stability of multiple inlet systems. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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胶州湾内外的涨、落潮三角洲上发育有一定规模的潮流沙脊体系,通过多波束调查采集数据和浅剖、沉积物资料的分析,对沙脊特征进行了研究。湾内涨潮三角洲上分别分布有冒岛沙脊、中央沙脊和岛耳河沙脊;湾外落潮三角洲上分别发育了潮流沙脊大竹、南沙、北沙和位于主潮流通道末端的弧状沙脊。潮流沙脊体系的演变具有较为明显的继承性。沙脊以海侵时期发育的沙体为内核,沉积物组成以粒度较粗的砂质沉积物为主,物源基础为低海平面时期胶州湾盆地内堆积的河流三角洲相沉积物。据分析,沙脊现代物源较为匮乏,整体目前处于冲刷不淤的状态。在现代潮流水动力条件下,研究区潮流沙脊处于活动状态。 相似文献
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长江口表层沉积物分布特征及动力响应 总被引：10，自引：1，他引：9
基于长江口2003 年2 月采集的58 个表层沉积物样品及以同步水动力资料的分析表明, 表层沉积物中值粒径自江阴-口外逐渐变细, 由江阴附近的217.8 μm 减少到南槽口外的12.1 μm; 浑浊带海域表层沉积物中值粒径北港最大, 平均为126.2 μm, 北槽其次, 平均为48.4 μm, 南槽最小, 平均为14.2 μm; 口外海域则北槽最大, 为22.4 μm, 北港其次, 为16.5 μm, 南槽最小, 为12.1 μm。沉积物分选性大多为中等-很差, 中值粒径越大, 分选系数越 小; 沉积物偏度大多是近对称-极正偏; 峭度表现为中等峭度-很窄尖。横沙以上区域表层 沉积物类型以砂为主, 口外海域沉积物类型以粘土质粉砂为主, 浑浊带海域表层沉积物类型复杂多样。长江口主槽表层沉积物中值粒径与落潮历时、Ve/Vf 值和余流值等动力参数呈正相 关关系, 落潮动力条件是决定长江口表层沉积物中值粒径大小的主要动力因素。 相似文献