Analysis of characteristics of time-frequency correlations between runoff, tidal range and salinity in the Changjiang Estuary   总被引：2，自引：0，他引：2  

FEI Yuejun  XU Lili  DU Panjun  GUAN Qinle  KANG Xing  XIAO Wenjun 《海洋学报(英文版)》2011,30(5):84-93

Power spectrum and cross-wavelet transform analysis was adopted to study the time-frequency characteristics and multiscale correlations between runoff, tidal range and salinity in the Changjiang Estuary based on the runoff data collected at the Datong Station, the tidal range measured at the Baozhen Station, and the salinity at the Baogang Station from 2008 to 2009. The variations of the salinity showed significant periodicity at scales of 2-3, 7-8, 14-15 and 26-30 d. The correlation between the salinity and the runoff and the tidal range were found to be significantly related to shock at scales of 5-7, 14-15, 26-30 d and 0.5 a. The correlation between the runoff and the salinity was mainly in the same phase, while the correlation between the tidal range and the salinity was in the antiphase. Different frequency bands were related to different degrees, and their relevance increased as the resonance frequency decreased. In addition, changes of the seasonal runoff were obvious. Specifically, a point of discontinuity was reached in early June with a cycle of 7-8 d, which coincided with the periodicity of plum rains in the Changjiang-Huaihe region. High-frequency changes (8-16 d period) of the salinity corresponded to the time domain in January-April 2008, February-April 2009 and October-December 2009 and exhibited an approximately 0.5 a (184 d) long frequency oscillation. Short-period changes were found to be stronger than long-period changes. Cross-wavelet transforms for the salinity, the runoff and the tidal range revealed local features in the time domain, while the significant levels of different periodic oscillations were observed in the frequency domain. The correlation characteristics of the salinity and the runoff were significant in the 80-90 d frequency domain, indicating that the major impact of the runoff on the salinity was reflected in seasonal changes. The tidal range on the small scale of 14-15 and 30-32 d was more obvious than the runoff.  相似文献   

Anthropogenic influences on shoreline and nearshore evolution in the San Francisco Bay coastal system   总被引：1，自引：0，他引：1  

Kate L. Dallas  Patrick L. Barnard 《Estuarine, Coastal and Shelf Science》2011

Analysis of four historical bathymetric surveys over a 132-year period has revealed significant changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of San Francisco Bay estuary. From 1873 to 2005 the San Francisco Bar vertically-eroded an average of 80 cm over a 125 km² area, which equates to a total volume loss of 100 ± 52 million m³ of fine- to coarse-grained sand. Comparison of the surveys indicates the entire ebb-tidal delta contracted radially, with the crest moving landward an average of 1 km. Long-term erosion of the ebb-tidal delta is hypothesized to be due to a reduction in the tidal prism of San Francisco Bay and a decrease in coastal sediment supply, both as a result of anthropogenic activities. Prior research indicates that the tidal prism of the estuary was reduced by 9% from filling, diking, and sedimentation. Compilation of historical records dating back to 1900 reveals that a minimum of 200 million m³ of sediment has been permanently removed from the San Francisco Bay coastal system through dredging, aggregate mining, and borrow pit mining. Of this total, ∼54 million m³ of sand-sized or coarser sediment was removed from central San Francisco Bay. With grain sizes comparable to the ebb-tidal delta, and its direct connection to the bay mouth, removal of sediments from central San Francisco Bay may limit the sand supply to the delta and open coast beaches.  相似文献   

Numerical modeling of hyperpycnal flows in an idealized river mouth     

Yan Wang  Houjie Wang  Naishuang Bi  Zuosheng Yang 《Estuarine, Coastal and Shelf Science》2011

Numerical experiments in an idealized river mouth are conducted using a three-dimensional hydrodynamics model (EFDC model) to examine the impacts of suspended sediment concentration (SSC), settling velocity of sediment and tidal mixing on the formation and maintenance of estuarine hyperpycnal flows. The standard experiment presents an illustrative view of hyperpycnal flows that carry high-concentrated sediment and low-salinity water in the bottom layer (>1.0 m in thickness) along the subaqueous slope. The structure and intra-tidal variation of the simulated hyperpycnal flows are quite similar to those previously observed off the Huanghe (Yellow River) mouth. Results from the three control experiments show that SSC of river effluents is the most important parameter to the formation of hyperpycnal flows. High SSC will increase the bulk density of river effluents and thus offset the density difference between freshwater and seawater. Low SSC of river effluents will produce a surface river plume, as commonly observed in most large estuaries. Both the settling velocity of sediment particles and the tidal mixing play an important role in maintaining the hyperpycnal flows. Increasing settling velocity enhances the deposition of sediment from the hyperpycnal layer and thus accelerates the attenuation of hyperpycnal flows, whereas increasing tidal mixing destroys the stratification of water column and therefore makes the hyperpycnal flows less evident. Our results from numerical experiments are of importance to understand the initiation and maintenance of hyperpycnal flows in estuaries and provide a reference to the rapidly decaying hyperpycnal flows off the Huanghe river mouth due to climatic and anthropogenic forcing over the past several decades.  相似文献   

Numerical study of M₂ internal tide generation and propagation in the Luzon Strait   总被引：1，自引：1，他引：0  

LI Huan  SONG Dan  CHEN Xueen  QIAN Hongbao  MU Lin  SONG Jun 《海洋学报(英文版)》2011,30(5):23-32

Based on the z-coordinate ocean model HAMSOM,we introduced the internal-tide viscosity term and applied the model to numerically investigate the M2 internal tide generation and propagation in the Luzon Strait (LS).The results show that (1) in the upper 250 m depth,at the thermocline,the maximum amplitude of the generated internal tides in the LS can reach 40 m;(2) the major internal tides are generated to the northwest of Itbayat Island,the southwest of Batan Island and the northwest of the Babuyan Islands;(3) during the propagation the baroclinic energy scattering and reflection is obvious,which exists under the effect of the specific topography in the South China Sea (SCS);(4) the westward-propagating internal tides are divided into two branches entering the SCS.While passing through 118 E,the major branch is divided into two branches again.The strongest internal tides in the LS are generated to the northwest of Itbayat Island and propagate northeastward to the Pacific.However,to the east of 122 E,most of the internal tides propagate southeastward to the Pacific as a beam.  相似文献   

天津近海潮汐特征分析   总被引：1，自引：0，他引：1  

李希彬  孙晓燕  王世福  叶风娟  李玉杰  李秀艳 《海洋通报(英文版)》2011,13(1):40-49

对塘沽海洋环境监测站从1950年-2008年,59年的潮汐资料进行调和分析,分析了其分潮调和常数的变化曲线,并利用FFT谱分析方法对其调和常数的变化周期和原因进行了分析;之后应用FFT谱分析方法对去除天文潮后的余水位进行分解,分析了近50多年来年平均余水位的多层次周期分布,进而利用最小二乘法进行线性分析,分析了天津近海...  相似文献   

我国潮流能资源开发评述     

吕忻  郭佩芳 《海洋湖沼通报》2011,(1):26-30

潮流能无污染,可预测性高,环境影响小,是一种非常有发展潜力的可再生能源.近年来,潮流能开发技术发展迅速,日趋成熟.我国潮流能资源丰富,合理有效的开发潮流能资源对保障我国的能源安全意义重大.文中总结我国潮流能开发利用中存在的主要问题,提出我国潮流能开发工作的几点建议.  相似文献   

曹妃甸填海工程阻断浅滩潮道初期老龙沟深槽的地形变化     

尹延鸿  褚宏宪  李绍全  胡刚  毕世普  袁红明 《海洋地质前沿》2011,(5):1-6

通过研究1992、1997、2006年的测深资料,对比分析了横切老龙沟深槽口门处的地形横剖面和大致沿老龙沟深槽轴线的地形纵剖面,可知在此期间深槽内的水深有变浅和淤积的趋势.总体看来,老龙沟深槽的淤积厚度在0.61～4.8 m之间,并且老龙沟深槽轴线也有自东向西迁移的趋势.自2004年曹妃甸填海工程的通岛公路阻断浅滩潮道...  相似文献   

舟山凉潭岛填海工程对水动力及海床演变影响的模拟预测分析     

吴仁豪  童元正  张旭锋  赵晟  孙健  娄建富  王海平 《热带海洋学报》2011,(4)

用一个三维(ECOMSED)模式对舟山凉潭岛填海工程前后的潮流场变化进行模拟,做出预测。潮流场模拟结果与实测基本吻合。经分析可知,工程对潮流的影响主要在围堤的东南角小范围内:工程后流速明显减小,造成淤积现象,但淤积程度不大,1年后的淤积为13cm左右,5年后的淤积为0.8—1.2m左右。工程对较深水层的潮流运动影响很小。通过对施工期间产生的悬浮物在涨落潮时的分布模拟可知,涨潮时,悬浮物从工程区域的一个悬浮物源不断排出,主要对工程附近及其上游地区造成一定的影响;落潮时,悬浮物主要影响工程外围及其下游地区,整个落潮期间悬浮物能影响的范围比涨潮期间要大。总体上工程对该附近海域的潮流场及冲淤影响很小。  相似文献   

单点高频地波雷达资料估算潮能耗散的方法   总被引：1，自引：0，他引：1  

毛华斌  陈举  邱春华  练树民 《热带海洋学报》2011,(6)

使用嵊泗站所布设的地波雷达观测获取的径向流数据,以及嵊泗、芦潮港、岱山3个潮汐观测站水位资料,采用两点近似投影方法反演流场全矢量流速,并用T-Tide程序计算调和常数,分别计算O1、K1、M2、S2各分潮流速场及迟角场,并计算各点上的潮能通量及潮能耗散,得到嵊泗岛以西杭州湾口区域潮能耗散同地形存在良好对应关系,充分证明了采用地波雷达观测数据进行潮能耗散计算这一方法的可行性,供相关工作者作进一步研究和讨论.  相似文献   

胶州湾潮汐潮流高分辨率数值模拟研究     

陈金瑞  陈学恩  于华明  闫运伟  单士亮  赵健 《中国海洋大学学报(自然科学版)》2011,(Z2):29-35

基于采用无结构网格和有限体积方法的FVCOM陆架模式,考虑8个主要的天文分潮,建立胶州湾三维高分辨率数值模型来重现和研究其潮汐潮流变化状况。与实测资料对比验证表明,模拟结果与实测值吻合较好。在此基础上,根据模拟结果计算得到了较以往更为精细的同潮图和潮汐、潮流、余流分布特征。研究结果揭示,最大可能潮流和最大余流都发生在团岛附近,流速分别可达2.14和0.43 m/s;除了湾口附近前人报道过的4个余流系统外,还在中部首次揭示了2个相对较弱的余流系统;潮流能通量在内外湾口呈"左进右出"的结构;胶州湾的平均纳潮量为8.31亿m3;染色试验表明,胶州湾30 d的水交换率为36.8%。  相似文献