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Activity and Formation of sand waves on Northern South China Sea Shelf

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Journal of Earth Science 2010年第1期21卷 55-70页

作者：栾锡武彭学超王英民邱燕 Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of Sciences Guangzhou Marine Geological Survey Ministry of Land and Resources Basin and Reservoir Research Center China University of Petroleum(Beijing)

sand waves on the northern South China Sea shelf had been considered as stable relict bed form. For the industry use of sea bed between stations LF13-2 and LF13-1, a new round of explorations were conducted. The newly obtained data show that both spacings and amplitudes of sand waves are all systematically changing with water depth. Repeated observations since 2003 to 2004 showed that the sea bed is currently active. Due to strong erosion of surface sediment since Dongsha （东沙） uplifting, there are almost no modern sediments on the shelf of Dongsha area. sand materials in the study area mainly originate from the erosion of the bed sediment formation. The water depth increment revealed by repeated echo sounder data is mainly due to erosion. Bottom currents are quite complex in the area of Dongsha underwater plateaus. At site 9MKH, the southward ebb current is stronger than the north- ward flood current, while at site AEM-HR, the WNW-ward flood current is slightly stronger than the ESE-ward ebb current. At site 9MKII, the maximum bottom current speed is 48 cm/s, and 22% of the observed bottom current speeds are larger than 20 cm/s, which meet the minimum bottom current speed required for the creation of sand wave. This article points out that present-day oceanographic condition couples well with the sand-wave morphologies, and that the sand waves are to a great extent in equilibrium with the ongoing present-day oceanographic bottom current condition and active.

关键词： sand wave northern South China Sea shelf activity formation.

Priori knowledge based a bathymetry assessment method using the sun glitter imagery:a case study of sand waves on the Taiwan Banks

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Acta Oceanologica Sinica 2014年第1期33卷 120-126页

作者： SHAO Hao LI Yan LI Li State Key Laboratory of Marine Environmental Science Xiamen University Troops 91039 the Chinese People's Liberation Army Third Institute of Oceanography State Oceanic Administration

High resolution optical satellite imageries containing the sun glitter,similar to synthetic aperture radar（SAR） imageries,are useful in identifying and mapping of bottom topography in shallow *** errors in the previous studies are corrected,and a method for mapping submarine bottom topography is developed using the sun glitter satellite *** method is established on the basis of empirical description of a sand wave using an equation with two unknowns named r and *** order to determine r and k,a ＂trial and error＂ approach is introduced and testified by a case study on the Taiwan Banks using an ASTER *** results show that the inversed water depths match well with the sounding water *** agreement between the inversed results and the in situ measurements is about 78% by comparing 371 ***,this method has the advantage in keeping the original appearance of a sand wave,especially in positions around the sand wave *** fine agreement indicates that the imaging model is flexible and the approach developed is feasible.

关键词： sun glitter submarine topography sand wave Taiwan Banks

A LINEAR THEORY FOR DISTURBANCE OF COHERENT STRUCTURE AND MECHANISM OF sand waveS IN OPEN-CHANNEL FLOW

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International Journal of Sediment Research 2001年第2期16卷 234-243页

作者： Yuchuan BAI1, Andreas MALCHEREK2 and Changbo JIANG 1 Institute for Sedimentation on River and Coast Engineering, Tianjin University, Tianjin 300072, China. E-Mail: Ychbai@*** 2 Federal Waterways Engineering and Research Institute Institute for Sedimentation on River and Coast Engineering Tianjin University Tianjin 300072 China.E-Mail: Ychbai@*** Federal Waterways Engineering and Research Institute Coastal Department D-22559 Hamburg Germany.

The formation of sand wave is such a process in which the roughness and discontinuity of the original bed surface cause the disturbance of the bottom laminar flow in an open channel, and the development of the disturbance in turn leads to instability of the flow and the appearance of the coherent structure. The evolution and development of the coherent structure further promote the undulations of bed surface and sand waves rise finally. The sand wave is explained as a result of action that the bed sediment particles are disturbed by the coherent structure. This study shows that the sand wave formation is the result of disturbance action of neutral coherent structure, and the sand wave shape obtained in computations is identical to the practical one.

关键词： Coherent structure sand wave Open channel flows

EXPERIMENTAL　STUDY　ON　BED　FORMS　AND　FLOW　RESISTANCE　OF　LIGHT－WEIGHT　MATERIALS　WITH　DIFFERENT　DENSITIES

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Journal of Hydrodynamics 1995年第1期7卷 58-65页

作者： Duan, Guohong Wang, Guixian Tsinghua Univ Beijing China

Experiments were conducted to investigate bed forms and flow resistance of light-weight sediment in an open channel flow. Three different synthetic materials of specific gravity 1. 055, 1. 46, each with uniform sizes D50 for 1. 25mm, 1. 05mm, 1. 40mm were used. Some conclusions were obtained from the resultS of these experiments and the data of other reliable sources[1, 2, 3, 4]. They indicate that the grain resistence is greatly affected by D50, and bed form resistances is the function of the downstream slope and the height of the dune. As well as natural sand, Y is not only the function of Y', but also affected by the relative roughness Rb/D50 and the size of the sediment.

关键词： light-weight materials sand wave bed forms flow resistance.

BED FORMS AND RESISTANCE PROPERTIES OF LIGHT-WEIGHT BED MATERIAL

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International Journal of Sediment Research 1993年第3期 33-50页

作者： WANG Guixian ,WANG Xingkui,GUO Jiachao Professor, Sediment Research Laboratory, Dept. of Hydraulic Engineering, Tsinghua University, Beijing 100084, China. Associate Professor, Dept. of Hydraulic Engineering, Tsinghua University. Assistant, Dept. of Hydraulic Engineering, Tsinghua University.

Based on experimental results from a large tilting flume, the characteristics and de- veloping processes of bed forms of plastic particles during scouring and deposition are systematically studied. The relationships of the occurence, development and disappearence of sand waves with the flow conditions are presented. Various statistical characteristics of sand waves with different sizes and the corresponding resistance properties of different bed forms of plastic particles are obtained. These results have filled in the gaps in bed forms and resistance properties of light sediment particles. It also serves as useful reference in the design of river model tests.

关键词： Bed form sand wave flow resistance light-weight bed material alluvial stream.

VARIATION OF FLOW AND ROUGHNESS CHARACTERISTICS IN FLUVIAL RIVERS

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International Journal of Sediment Research 1991年第3期 19-30页

作者： Tutomu Kishi Professor, Hokkaido Institute of Technology, Japan

The flow and roughness characteristics of fluvial rivers vary in accordance with the properties of the bed configurations. In field rivers, sand waves with different characteristic lengths are often formed simultaneously. This kind of bed configurations can hardly be observed in the flume experiments. In the present research, the bed configurations are classified into three types according to the type of bar and the characteristics of the resistance to flow are analysed in relation to the type of bar.

关键词： Roughness characteristics Bed configuration sand wave Bed shear stress