Short-term shoreline changes due to cross-shore structures: a one-line numerical model     

I. O. Leont'yev   《Coastal Engineering》1997,31(1-4)

The proposed numerical model simulates the short-term temporal changes in shoreline position due to a structure interrupting the longshore sediment flux. The impacts of both the groin-type construction and underwater trench of arbitrary orientation relative to the shore are discussed. In order to estimate the sediment mass trapped by the structure, a submodel of the longshore sediment transport induced by a random wave field is developed. The contribution of the surface roller in momentum balance as well as in sediment suspension is included. The shoreline changes are computed from the equation deduced from the mass conservation. The perturbations in the longshore sediment discharge caused by a structure are assumed to concentrate within some boundary area of which the spatial scale is proportional to the structure's length until the latter is exceeded by the width of the sediment flux. It is shown in particular that the total effect of a long trench (channel) and a pier in its nearshore part results in general shoreline recession except for the vicinity of a pier. The model is tested against the laboratory data of Baidei et al. (1994) and applied to the Baidara Bay coast (Kara Sea) where a pipeline would be designed.  相似文献   

夏季长江冲淡水转向机制分析   总被引：7，自引：0，他引：7  

廖启煜  郭炳火  刘赞沛 《海洋科学进展》2001,19(3):19-25

利用 1 95 9,1 975 - 1 982年及 1 998年夏季各月黄、东海盐度分布和相应风场资料 ,分析讨论了长江冲淡水夏季的扩展路径。指出 :除海底坡降外 ,由 S向的苏北沿岸流和 N,NE向的浙东沿岸流及台湾暖流构成的“力偶”,是使冲淡水向左扭转的重要外力之一。用近岸均质模型和远岸双层模型的涡度方程定性讨论了冲淡水的转向机制  相似文献   

哀牢山-红河断裂带中段应变分析   总被引：1，自引：0，他引：1  

周勇  吴世敏  周萍 《热带海洋学报》2003,22(2):17-29

对哀牢山—红河断裂带中段和平—水塘剖面、墨江—元江剖面和其它地段的岩石应变及磁组构进行了分析，表明应变强度的校正磁各向异性度PJ从断裂带向西至三叠系明显降低，变形强度向西迅速减弱。磁化率椭球体主轴展布反映出剪切带内、外变形方式的改变。剪切带内，以水平走滑运动为主；向西则以水平缩短为主。在应变分析中，对断裂带内的S—C组构两组面理夹角、杏仁体和石榴石应变标志体进行了测量，结果显示，剪切带内的磁组构和岩石组构间关系较差。此外，还对这两条剖面中的三叠系进行了应变和磁组构分析，找出了它们与磁化率椭球体对应轴率间的相关性。  相似文献   

几种测流设备的比测试验及分析   总被引：2，自引：0，他引：2  

李震  冯雷  邱薇  刘念  王长红 《海洋技术学报》2006,25(4):42-45,64

海流是基础的海洋资料,海流计是海流测量的重要仪器。文中介绍了RCM-9型安德拉海流计、中科院声学所150 kH z ADCP、RD I公司75kH z相控阵ADCP以及LADCP四种声学海流计的工作原理以及海上比测试验。通过分析比测试验的结果,验证了各仪器的测流性能,并从层厚、层深、相对流速参考物以及安装位置等方面分析了造成各设备测量差别的原因,为将来的流速测量提供了参考依据。  相似文献   

Experimental Study on Vortex-Induced Vibrations of Submarine Pipeline near Seabed Boundary in Ocean Currents   总被引：2，自引：3，他引：2  

杨兵高福平  吴应湘李东晖 《中国海洋工程》2006,20(1):113-121

1 .IntroductionThe submarine pipeline is a commonfacility widely usedfor offshore oil and gastransport . Whena pipeline is installed on a seabed and not buried,unsupportedspans may exist insomelocations ,es-peciallyinthe uneven zones of the seabed.The spa…  相似文献   

Regional variation in springtime ichthyoplankton assemblages in the northeast Pacific Ocean     

Miriam J. Doyle  Kathryn L. Mier  Morgan S. Busby  Richard D. Brodeur   《Progress in Oceanography》2002,53(2-4)

The coastal regions of the northeast Pacific support large, economically valuable fishery resources and provide nursery areas for many fish species. Over the last few decades, there have been dramatic shifts in species abundance and composition in this area. In this paper, we examine the springtime spatial patterns in the ichthyoplankton of three oceanographically different regions, the Southeast Bering Sea, the Gulf of Alaska and the U.S. West Coast. The data examined are a subset of a larger database (comprising data from cruises conducted from 1972 to 1997) that is being used to investigate spatial, seasonal and interannual patterns in ichthyoplankton of the northeast Pacific in relation to environmental conditions. Ichthyoplankton were collected during seven cruises using 60-cm bongo nets. Spatial patterns of ichthyoplankton were examined using both classification and ordination techniques. Relative Bray-Curtis dissimilarity coefficients calculated from the log₁₀ (n+1) of abundance data were used as input to the numerical classification of species and stations. Nonmetric multidimensional scaling was also applied to the abundance data to examine geometric patterns in the data. The numerical analyses of the species abundance data sets for each cruise revealed spatial patterns in the ichthyoplankton that suggest the occurrence of geographically distinct assemblages of fish larvae in each region. For all three sampling regions, the assemblage structure is primarily related to bathymetry, and Shelf, Slope, and Deep-Water assemblages are described. This shallow to deep-water gradient in species occurrence and abundance reflects the habitat preference and spawning location of the adult fish. Another degree of complexity is superimposed on this primary assemblage structure in each region and seems to be related to local topography and the prevailing current patterns. The patterns in ichthyoplankton assemblages of the three regions in the northeast Pacific Ocean described here form the basis for future investigations of spatial and temporal patterns in the ichthyoplankton of the subarctic Pacific.Regional Index Terms: Northeast Pacific Ocean, Southeast Bering Sea, Gulf of Alaska, U.S. West Coast.  相似文献   

Changes in the mesozooplankton community associated with the hydrography off the northwestern Iberian Peninsula   总被引：2，自引：0，他引：2  

Blanco-Bercial  Leocadio; Alvarez-Marques  Florentina; Cabal  Jesus A. 《ICES Journal of Marine Science》2006,63(5):799-810

  相似文献   

Diel variation in the catchability of gadoids and its influence on the reliability of abundance indices   总被引：3，自引：5，他引：3  

Michalsen  Kathrine; Godo  Olav Rune; Ferno  Anders 《ICES Journal of Marine Science》1996,53(2):389-395

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夏季流经东沙群岛北侧的一支偏西向海流     

黄企洲  王文质  傅孙成  陈荣裕  李毓湘  周国荣 《热带海洋学报》1997,(2)

主要根据1992年8月中国科学院南海海洋研究所和香港理工大学合作进行的“南海环流试验”的调查资料，并引用中国科学院南海海洋研究所1982年7月、1985年8月在南海东北部的调查资料、黑潮合作调查（CSK）的资料，通过温、盐度分布特征的分析，并结合动力计算结果，指出夏季在南海东沙群岛北侧存在着一偏西向海流，它的流动路径与文献[5－7]中所说的南海黑潮分支的流动路径显著不同。对夏季南海海流的三维数值模拟也得到了相似的结果。  相似文献   

长江口三维潮流数值计算及动力分析   总被引：10，自引：1，他引：10  

于凤香  宋志尧  李瑞杰 《海洋湖沼通报》2003,(3):14-23

采用三维动力学数学模型对长江口潮流场进行了计算，对长江口潮流流态在一个潮周期内逐时进行了分析，并对长江口南支盐水倒灌从动力学角度进行了初步探讨。计算结果表明：文中模型较好地重演长江口潮流场，可以用于大型复杂河口工程实际中的潮流场的计算和分析。  相似文献