天津潮间带高程现状与滨海新区城市安全   总被引：2，自引：2，他引：0  

王福  裴艳东  李建芬 《地质通报》2010,29(5):682-687

通过6条潮间带水准测量剖面,对天津滨海新区潮间带的高程及坡度进行了测量和计算。结果显示:人工岸线(海堤、海防公路等)与滩面交汇处的高程为+0.22m~+0.73m(1956黄海高程);天津潮间带的平均坡度为1.25‰,海河南侧滩面的平均坡度为1.09‰,较北侧1.33‰小,海河北侧从蛏头沽剖面(1.21‰)到大神堂剖面(1.58‰)滩面坡度呈现变大的趋势;结合潮位观测数据,获得了潮间带的出落宽度,永定新河潮间带最宽,为1730~1810m,大神堂潮间带最窄,为1090~1160m。与20世纪80年代对比,滩面已变陡、变窄。进一步的滩面高度与潮位对比发现,滩面与人工岸线交汇处的高程均低于平均高潮位,揭示了海防设施受到海水直接影响的现状。海防设施真正地成了保护城市的唯一屏障,因此应该进一步加高、加固海防设施,提高防灾等级。  相似文献   

天津市潮滩活体和埋藏有孔虫群的分布及地质环境意义   总被引：1，自引：0，他引：1  

李建芬  裴艳东  王福  王宏 《海洋地质与第四纪地质》2009,(3)

对天津市潮滩8条垂直于海岸线剖面的57个表层沉积物样品进行了活体和死体有孔虫分析鉴定、粒度分析、含盐量测定,利用全站仪对剖面进行了水准测量,同时测定了海水盐度。研究了天津市潮滩有孔虫群的组成、数量及分异度等特征;通过聚类分析将天津市潮滩活体有孔虫群分为7个带,埋藏有孔虫群(活体+死体)分为5个带,但除了埋藏群Ⅰ、Ⅳ与活体有孔虫群Ⅰ、Ⅳ组合特征一致外,其他各带的组合特征及分带界线均不一致。通过分析活体有孔虫群分带与沉积物含盐量、海水盐度、潮位、沉积物组成等生态环境参数的关系,探讨了活体有孔虫群的主要控制因素;通过分析埋藏有孔虫群分带与潮位、沉积物粒径、现代沉积速率等沉积环境参数的关系,探讨了埋藏有孔虫群的搬运及沉积作用。指出了天津市海岸带活体有孔虫群和埋藏有孔虫群的关系、环境特征及地质意义,为该区高精度的古沉积环境划分提供了重要指标。  相似文献   

广东红海湾海流季节性特征分析          下载免费PDF全文

王春阳  张永强  王恩康  金永德 《应用海洋学学报》2020,39(4):480-489

基于2017年春季和冬季的海流资料分析了红海湾海区海流特征、潮流状况、涨落潮流特性、余流特征及表层漂流特征。研究海域共布设3个临时潮位观测站和11个全潮水文观测站。根据流速、流向过程曲线和潮位过程曲线的关系，得出涨(落)潮流速最大的时刻和最小流速发生时刻与潮位关系并非固定在高(低)潮时或半潮面左右，由此看出，研究海域的潮波介于驻波与前进波之间，属于不规则半日潮流主导的海域。研究海域中大部分站位潮流属于往复流，少数站位潮流运动具有一定的旋转性，平均涨潮流速最大为7 cm/s，平均退潮流速最大为14 cm/s。春季大潮期和中潮期各站余流流向整体为偏东向，小潮期，除少数测站余流流向偏向南东向，其余测站余流流向偏西向；冬季大潮期和中潮期各站余流流向整体为偏西向，小潮期，湾西侧余流流向偏西向，湾东侧余流流向偏南东向。垂向上各层余流流速由表至底逐渐减小，流向基本一致。  相似文献   

Mercury fluxes between an impacted coastal lagoon and the Atlantic Ocean   总被引：1，自引：1，他引：0  

P. Pato  C. Lopes  M. Vlega  A.I. Lilleb  J.M. Dias  E. Pereira  A.C. Duarte 《Estuarine, Coastal and Shelf Science》2008,76(4):787-796

The objective was to estimate the seasonal and inter-tidal variability of dissolved and particulate mercury fluxes between the Ria de Aveiro (Portugal) and the Atlantic Ocean. The mercury fluxes were estimated by means of a two-dimensional vertically integrated hydrodynamic model. Results showed that the particulate fraction plays an important role in the transport of mercury while the contribution of the seston fraction to the transport of mercury was always <0.5%. During spring tides, in summer, about 2% of mercury transported in seston was present in an organic form. The mass balance for the mercury fractions revealed that the mercury export to the Atlantic Ocean varied with season and tidal regime, mainly in terms of the relative importance of the dissolved and particulate fractions. An approximate range of values for the annual mass balance between 42 and 77 kg shows that the export of dissolved and particulate mercury makes little impact on the near shore region of the Atlantic Ocean and that the recovery of the lagoon from mercury contamination is likely to remain a long-term issue.  相似文献   

A numerical study of tidal asymmetry in Okatee Creek,South Carolina   总被引：1，自引：0，他引：1  

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   

Do shorebirds graze down zoobenthic biomass at the Banc d'Arguin tidal flats in Mauritania?     

Wim J. Wolff  Hermann Michaelis 《Estuarine, Coastal and Shelf Science》2008,79(3):491-495

The 500 km² of tidal flats at the Banc d'Arguin, Mauritania, are a wintering site for over 2 million shorebirds, making this one of the areas with the highest density of shorebirds in the world. In earlier studies, it was found that these huge numbers of birds are dependent on a rather low biomass of benthic animals. To explain this paradoxical situation, we hypothesized that the earlier assessments of biomass in late winter and early spring do not reflect a year-round situation. Benthic biomass may be high when the birds arrive in autumn to be subsequently grazed down in the course of winter. To test this hypothesis, we have determined benthic biomass in September 1988. The result has been compared with a biomass value obtained in February–April 1986 with the same methods and at the same stations. These two biomass values do not differ significantly; so our hypothesis has to be rejected. It has to be admitted, however, that our experimental design cannot discern between differences due to the year of sampling and those due to the season.  相似文献   

散射光对准确CCD平场的影响--修改某些反光镜挡光筒的必要性   总被引：1，自引：0，他引：1  

姚保安  张春生  沈昌钧  彭云楼 《天文学报》2005,46(3):343-352

继前文之后，进一步说明，晨昏蒙影平场与夜天露光的差别主要由于存在散射光．像Grundahl和Sorensen那样，上海天文台1．56米和南京大学63厘米反光镜的针孔像也已获得，直观地显示了散射光的存在，1．56米和63厘米反光镜都有标准设计的挡光筒，所有标准设计的反光镜都只有两个挡光筒，分别置于主镜和付镜前面．为了在得出准确平场时CCD不受散射光影响，这样的挡光筒是不够的．这是所有标准设计的档光筒共同的弱点．为了得到更准确的平场改正，修改所有类似的反光镜主镜挡光筒是极其重要的。  相似文献   

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刘序俨  洪星 《大地测量与地球动力学》2007,27(4):82-86

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Comparison between Different Models of Galactic Tidal Effects on Cometary Orbits     

Marc Fouchard  Christiane Froeschlé  John J. Matese  Giovanni Valsecchi 《Celestial Mechanics and Dynamical Astronomy》2005,93(1-4):229-262

Different models of the action of the galactic tide are compared. Each model is a substitute for direct numerical integrations allowing a drastic decrease of the computation time. The models are built using two different techniques, (i) averaging of the fast variable (the mean anomaly) over one cometary period and (ii) fixing the comet in its aphelion direction. Moreover, we consider two different formalisms (Lagrangian and Hamiltonian) and also two different sets of variables. As expected, we find that the model results are independent of the formalism and the set of variables considered, and are highly accurate, whereas mathematical technique leads to poor results. In order to further reduce the computation time, mappings are built from the development of the solution of the models. We show that for these mappings, the set of variables giving the most accurate results is strongly dependent on the cometary eccentricity, e, and semimajor axis, a.  相似文献   

曹妃甸老龙沟潮汐通道拦门沙演变机制   总被引：2，自引：0，他引：2  

季荣耀  陆永军  左利钦 《水科学进展》2011,22(5):645-652

渤海湾曹妃甸老龙沟海区属于泻湖型潮汐通道体系,口门附近发育有大规模拦门沙浅滩。由于沿岸泥沙供给不足,近几十年来东坑坨等沙坝外侧海区整体呈侵蚀冲刷态势,等深线向陆蚀退。老龙沟西支深槽也以侵蚀作用为主,而拦门沙地区滩槽冲淤变化则与东坑坨演变密切相关。其中东槽冲刷发展主要是东坑坨西南尾端淤长压迫老龙沟口门,引起岬角效应增大、潮流动力增强所致,而西槽的摆动现象则主要与东槽发展所产生的挤压作用有关。由于泥沙供给不足,近年来东槽发展和西槽摆动的速度都有明显减缓。  相似文献