我国东部沿海地区理论最低潮面与平均潮差关系研究

基于理论最低潮面与平均潮差的内在联系,利用我国东部沿海17个验潮站连续369天的逐时潮位资料,进行调和分析得到相应的调和常数,并计算理论最低潮面。藉此,就理论最低潮面与年平均潮差及月平均潮差之间的关系进行统计分析。结果表明,理论最低潮面与年平均潮差及月平均潮差之间均具有较高的相关性,实际工程中可以利用此关系近似地确定当地理论最低潮面。     

日本“311”海啸对江苏北部沿海影响分析

北京时间2011年3月11日13时46分日本东北部发生里氏9.0级强烈地震,江苏北部的灌河口潮位站正好记录下海啸期间的潮位资料。由于以往对海啸波动的过滤提取方法不统一,而且人为因素影响较大,误差积累影响了后续科研工作的进行。提出综合利用小波能谱、功率谱和滤波分析等方法结合海啸识别结果来提取海啸波的方法,并且成功提取出灌河口站海啸波的周期范围、影响时间和最大波峰。同时采用COMCOT海啸数学模型,讨论了江苏沿海海啸波传播方式,解释了灌河口潮位站海啸波最大波峰未出现在第一波的原因,是因为江苏北部山东半岛特殊的地形使得在黄海传播的海啸波发生反射,与之前的波动产生叠加效果导致的。分析结果表明:江苏沿海由于海啸直接引起的海啸波不高,但是海啸波叠加之后,最大波高却是之前的2倍,因此在海啸预报中应该全面考虑地理位置特点,分析海啸波运动的反射叠加等特征,从而提高预报质量。     

论二叠系-三叠系界线定义

<正> 一个合理的二叠系-三叠系界线定义对于正确划分它的界线和选择它的层型剖面是十分必要的。自1971年国际二叠系-三叠系界线会议(Calgary,Canada)以来,二叠系-三叠系界线研究有了很大的进展。在1984年莫斯科国际地质大会召开期间举行的二叠系-三叠系界线工作会议上,多数委员赞同以Otoceras 带的底为三叠系底界的传统定     

喜马拉雅地区(我国境内)地层研究的新认识

<正> 1966—1968年珠穆朗玛峰地区的科学考察,为喜马拉雅地区(我国境内)的地层研究建立了良好的基础。1973—1976年,在西藏科学考察中,又获得比较丰富的地层、古生物资料。本文在上述工作和所获新资料的基础上,概要地介绍喜马拉雅地区(我国境内)地层研究的一些新认识。     

中国西藏南部珠穆朗玛峰地区的地层

珠穆朗玛峰(以下简称珠峰)地区系指亚东以西,吉隆以东,雅鲁藏布江以南的我国境内广大地区。于1966年～1968年我国无产阶级文化大革命期间,由中国科学院主持,对这一地区进行了大规模的科学考察。在地层古生物方面,也同其它学科一样,获得了非常丰富的资料。在这个地区首次发现了奥陶系、志留系和泥盆系,并对中生代和新生代地层作了较详细的分层工作,从而初步建立了珠峰地区比较完整的地层系统。由奥陶系至老第三系厚达一万米的海相地层,大多是连续沉积的。     

Analysis on Suspended Sediment Deposition Rate for Muddy Coast of Reclaimed Land

A new expression for calculating suspended fine-sediment deposition rate is developed based on theoretic analysis and experiments. The resulting equation is applied to simulation of fine sediment deposition in the reclaimed land in the Hangzhou Bay, China. The hydrodynamic environment in this area is solved by use of a long wave model, which gives the 2D-velocity field and considers bathymetric changes due to fine sediment deposition. The expression is proved convenient to use in engineering practice, and the predicted deposition rate agrees with the annual data available from field measurements from the first year to the third year after the construction of the long groin as a reclaiming method.     

遥感水下地形成图技术

介绍了应用卫星遥感结合地理信息系统技术将历史水下地形反演,也可以小范围地扩大地形出图的最新技术在海岸工程规划、江河航道工程规划、水库库容计算、潮滩演变分析等方面的应用。     

江苏条子泥沙洲内缘区潮滩粒度特征及其影响因素

条子泥沙洲位于江苏岸外辐射沙脊群的核心区,水动力条件独特,地貌复杂.利用2009年5月11日在条子泥沙洲内缘区3条断面的潮滩表层沉积物粒度资料,分析该区域潮滩沉积物的粒度参数特征、沉积物粒度组成及沿程变化等,探讨不同岸段的沉积特征与水动力环境特征的相关性,以及影响潮滩沉积特征的主要因素等.结果表明,潮滩沉积物以砂质粉砂...     

Comparison of turbulence schemes for prediction of wave-induced near-bed sediment suspension above a plane bed

Based on a wave bottom boundary layer model and a sediment advection-diffusion model, seven turbulence schemes are compared regarding their performances in prediction of near-bed sediment suspension beneath waves above a plane bed. These turbulence algorithms include six empirical eddy viscosity schemes and one standard two-equation k-ε model. In particular, different combinations of typical empirical formulas for the eddy viscosity profile and for the wave friction factor are examined. Numerical results are compared with four laboratory data sets, consisting of one wave boundary layer hydrodynamics experiment and three sediment suspension experiments under linear waves and the Stokes second-order waves. It is shown that predictions of near-bed sediment suspension are very sensitive to the choices of the empirical formulas in turbulence schemes. Simple empirical turbulence schemes are possible to perform equally well as the two-equation k-ε model. Among the empirical schemes, the turbulence scheme, combining the exponential formula for eddy viscosity and Swart formula for wave friction factor, is the most accurate. It maintains the simplicity and yields identically good predictions as the k-ε model does in terms of the wave-averaged sediment concentration.     

Propagation Mechanisms of Incident Tsunami Wave in Jiangsu Coastal Area, Caused by Eastern Japan Earthquake on March 11, 2011

At 13:46 on March 11, 2011 (Beijing time), an earthquake of Mw=9.0 occurred in Japan. By comparing the tsunami data from Guanhekou marine station with other tsunami wave observation gathered from southeast coastal area of China, it was evident that, only in Guanhekou, the position of the maximum wave height appeared in the middle part rather than in the front of the tsunami wave train. A numerical model of tsunami propagation based on 2-D nonlinear shallow water equations was built to study the impact range and main causes of the special tsunami waveform discovered in Jiangsu coastal area. The results showed that nearly three-quarters of the Jiangsu coastal area, mainly comprised the part north of the radial sand ridges, reached its maximum tsunami wave height in the middle part of the wave train. The main cause of the special waveform was the special underwater topography condition of the Yellow Sea and the East China Sea area, which influenced the tsunami propagation and waveform significantly. Although land boundary reflection brought an effect on the position of the maximum wave height to a certain extent, as the limits of the incident waveform and distances between the observation points and shore, it was not the dominant influence factor of the special waveform. Coriolis force’s impact on the tsunami waves was so weak that it was not the main cause for the special phenomenon in Jiangsu coastal area. The study reminds us that the most destructive wave might not appear in the first one in tsunami wave train.