Storm-generated current in La Jolla Submarine Canyon,California

Current meters were operating in La Jolla Submarine Canyon at 200 m depth during a period of high seas and onshore winds up to 62 km/h (34 knots). The meters were subsequently extracted from a kelp tangle by use of a deep-diving vehicle 0.5 km downcanyon from their emplacement position. The records show a downcanyon speed up to 50 cm/sec, considerably higher than any of our numerous earlier measurements. This was followed by an abrupt termination of data, evidently due to being engulfed in seaward-moving kelp masses. The record may provide evidence of the initial stages of a turbidity current. The conditions for such a current were provided by the piling up of water at the canyon head by the unusually strong onshore wind.     

乐清湾悬沙的浓度分布与运移

本文根据冬、夏、秋3季29站次的周日水文泥沙观测资料,通过对悬沙浓度和单宽输沙特征值的计算,讨论了该湾悬沙浓度的分布规律以及单宽输沙与悬沙运移的特点。     

海岸悬沙运移数学模型

根据适合大范围缓变地形情况下,不恒定、非均匀流场中随机波折绕射联合数值模式及波浪作用下的二维浅水环流方程和悬沙扩散方程,建立了波浪、潮流共同作用下二维悬沙数学模型,并将该模型应用于渤海湾北部海域,进行了波、流共同作用下航道疏浚弃土的悬沙扩散、运移及海床演变的数值模拟,为工程单位决策提供科学依据     

Modeling of suspended sediment transport with waveinduced longshore current in Huanghe (Yellow) River Delta

A three-dimensional suspended sediment model(SED)developed by the present authors is coupled with the combinatorial model of COHERENS(Luyten et al.,1999) (the three-dimensional coupled hydrodynamical-ecological model for Regional and Shelf Seas) and SWAN(Holthuijsen et al.,2004) (the third generation wave model).SWAN is regarded as a subroutine of COHERENS and gets time-and space-varying current velocity and surface elevation from COHERENS.COHERENS gets time-and space-varying wave relevant parameters provided by SWAN.Effects of wave on current are applied in bottom shear stress,wave-induced depth-dependent radiation stress and surface drag coefficient calculation.At the same time,the damping function of suspended sediment on turbulence is introduced into COHERENS.So the sediment model SED has feed back on circulation model COHERENS.The SED obtains current as sociated parameters from COHERENS.Then a couple dhydrodynamic-sediment model COHERENS-SED being able to account for interaction between wave and current is obtained.COHERENS-SED is adopted to simulate three-dimensional suspended sediment transport in the Huanghe River delta.In terms of simulation results,there is obvious diffierence between top and bottom layer of wave-induced longshore current.The values of time series of sediment concentration gotten by COHERENS-SED have,generally,an accepted agreement extent with measurement.Significant wave heights and wave periods obtained by COHERENS-SED show that wave simulation case with current’s effect can give better agreement extent with measurement than case without current’s effect.In the meantime,suspended sediment concentration distributing rule obtained by COHERENS-SED is similar to former researches and measurement.     

A three-dimensional model of suspended particulate sediment transport

Depth-averaged, one-dimensional and two-dimensional numerical models of bed and suspended particulate sediment transport provide unreliable answers for siltation and erosion quantities in situations dominated by three-dimensional flow patterns, as occur in harbour entrances due to flow separation and wind and density currents. Consequently, a numerical scheme has been developed which solves the complete three-dimensional diffusion-advection equation for suspended sediment concentration and thereby makes possible the study of siltation problems in complex, three-dimensional flows. The model analogue is based on a splitting technique and employs a mixed characteristics and finite difference approach. The accuracy and usefulness of the resulting scheme have been investigated by applying it to a number of hypothetical situations and to a laboratory situation involving the transport and dispersal of lightweight sediment. The results of the various tests show that the proposed approach works well and provides a useful basis for the study of practical problems.     

澳大利亚水下峡谷的演化

在所有的大陆中,澳大利亚是最平坦的,但其海底地形被极度切割,在 5 000 m深处分布着被海水掩盖的高高的山峰。从澳大利亚最大的墨累河口开始的水下峡谷体系,在深度上超过了深达 1 5 km的美国亚利桑那州著名的科罗拉多河大峡谷。这个水下体系的地质和地貌尚未得到很好的研究。2003年 2—3 月,在这里进行了国际考察AUSCAN(澳大利亚峡谷考察),其主要目的是收集有关水下峡谷和大陆边缘演化的信息,以及找到本区在晚第四纪遭到气候变化的证据。租得的法国研究船“玛丽恩·达弗林斯”号,装备了最新技术设施。来自澳大利亚、美国、法国、德国…     

Numerical study of three-dimensional suspended sediment transport in waves and currents

In the present work, a three-dimensional suspended sediment model (SED) is built. A three-dimensional hydrodynamic model (COHERENS) and a third-generation wave model (SWAN) are fully coupled through accounting for mutual influences between wave and current in them. SED is combined with the coupled model built up above. Damping function of suspended sediment on turbulence is introduced into COHERENS. Then a coupled hydrodynamic–sediment model COHERENS-SED incorporating mutual influences between wave and current is obtained. COHERENS-SED is adopted to simulate three-dimensional suspended sediment transport of Yellow River Delta with wave–current co-existing. The simulated tidal current velocities and suspended sediment concentration match well with field measurement data. The simulated significant wave height and wave period for a case with current's effects can give better agreement with measurement data than a case without current's effects. Numerical simulation results of COHERENS-SED are demonstrated to be reasonable though being compared with previous studies and field measurements [Wang, H., Yang, Z.S., Li, R., Zhang, J., Chang, R., 2001. Numerical modeling of the seabed morphology of the subaqueous Yellow River Delta. International Journal of Sediment Research 16(4), 486–498; Wang, H., 2002. 3-dimensional numerical simulation on the suspended sediment transport from the Huanghe to the Sea. Ph.D. Thesis, Ocean University of China, pp. 12–14 (in Chinese)].     

黄河口挑河河口悬沙分布与输移特征研究

基于实测资料对黄河废弃河道挑河河口段的悬沙分布及输移特点进行了研究。结果表明:挑河河口段悬沙浓度与潮流流速正相关,风浪作用则导致悬沙质量浓度大大提高;在空间尺度上悬沙浓度呈河口高、河道上游低的特点;挑河河口附近,涨潮流输沙明显占优势,向河道内侧,悬沙输移率有所降低,且逐渐转变为落潮输沙占优势。结合河口外侧海域冲淤演变趋势以及悬沙输运动力机制,认为河口段河道总体处于弱淤积状态,而风浪作用可以加速河道淤积。本研究可为挑河的河口演变和航道整治等提供参考。     

闽江口入海悬沙输运的数值模拟

闽江河口位于福建省东部,本文利用欧拉-拉格朗日差分方法模拟闽江口及附近海域在不同径流下的潮流场,并建立拉格朗日水质点跟踪方法近似模拟了悬沙在海域中的迁移过程．水质点运动轨迹计算结果表明,闽江口悬沙在外海主要向南方或东南方输运,其轨迹呈现螺旋线．在洪峰流量下,悬沙运移距离较远．     

乐清湾悬沙输移机制分析

以乐清湾海区特征测站实测资料为据,运用机制分解法将悬沙净输移通量分解成多个动力项并讨论不同区域悬沙输移的时空分布特征,认为潮泵输沙在湾内贡献均较大,在浅滩附近占明显优势,垂向净环流输沙在小潮期中,内湾作用显著,平流输沙在开阔水域及中湾深槽起主要作用.从余流分布、流速与含沙量的相位关系、垂向余流结构与悬沙浓度垂向梯度变化...     

Preliminary results on suspended sediment transport by tidal currents in Gomso Bay,Korea

This study briefly investigated sediment transport by tidal currents in Gomso Bay, on the mid-west coast of Korea during the summer season. Hydrodynamic measurements with benthic tripods (TISDOSs) show that near-bed suspended sediments are transported toward the bay mouth along the low-water line of tidal flats in the southern part of the bay, while they are directed offshore in front of the major tidal channel at the bay mouth according to tidal asymmetry. However, suspended sediments in the main body of sea water, observed from transect and anchor-site measurements, indicate a consistent incoming toward the uppermost tidal flats. A brief episode of relatively strong winds from the west and southeast displays that wind waves can yield the near-bed suspended sediment concentrations (SSC) overwhelming the SSC by tidal currents alone in the remaining duration.     

巴达棱湾悬沙分布特征及动力机制

利用2007年4月和7月在巴达棱湾进行的旱季和雨季水位、流速、悬沙浓度的全潮观测资料,结合2007年5月~2008年4月周年风、波浪资料,分析该海域悬沙分布特征和运移趋势,并利用机制分解法分析悬沙输运机制。结果表明,研究海域的水体含沙量存在旱季低、雨季高的季节变化,以及大潮高、小潮低的潮期变化;在平面上表现出东西两侧大、中间小,近岸高、远海低的分布特征。单宽输沙量方向与余流方向一致,表现为旱季冲刷、雨季淤积,即旱季指向外海,雨季指向湾内。通量机制分析结果表明,欧拉余流是悬沙输运的主要控制因素,其方向和大小决定了泥沙输移方向和输移量,在水深较深海域,垂向重力环流是相对次要的,而在水深较浅的海域相对次要的是悬沙潮泵输运项。     

长江口涨潮与落潮流速和悬沙输运不对称性研究

为了量化比较海表层环境及温跃层环境对南太平洋长鳍金枪鱼渔场分布的影响程度;本研究采用2010-2012年南太平洋长鳍金枪鱼延绳钓渔船实际生产统计数据;结合卫星遥感所获取的海表面温度（sea surface temperature;SST）和海表面高度（sea surface height;SSH）数据以及Argo浮标所获取的温跃层上、下界水温和深度数据;运用外包络法分别构建了基于海表层环境变量、温跃层上界环境变量以及温跃层下界环境变量的3种栖息地适应性指数（habitat suitability index;HSI）模型。模型验证结果显示;基于海表层环境变量的HSI模型;HSI>0.6时所占产量比重为70.04%;投钩数量比重为70.86%;HSI>0.8时所占产量比重为24.92%;投钩数量比重为25.79%;基于温跃层上界环境变量的HSI模型;HSI>0.6时所占产量比重为82.17%;投钩数量比重为80.95%;HSI>0.8时所占产量比重为33.24%;投钩数量比重为32.69%;基于温跃层下界环境变量的HSI模型;HSI>0.6时所占产量比重为81.01%;投钩数量比重为81.54%;HSI>0.8时所占产量比重为43.51%;投钩数量比重为43.73%。研究发现;基于温跃层上界和下界环境变量的两个HSI模型预报精度明显高于基于表层环境变量的HSI模型;且基于温跃层下界环境变量的HSI模型预报精度高于基于温跃层上界环境变量的HSI模型。研究结果表明;相较于海表层环境;温跃层环境;尤其是温跃层下界环境特征对南太平洋长鳍金枪鱼资源分布的影响更为显著。     

二维悬沙长期输运速度的定义和机理分析

将悬沙和水体的长期输运分离研究,给出二维悬沙长期输运速度的定义。从理论上分析了各种物理过程对二维悬沙长期输运速度的影响机理。采用部分观测资料,对长江口二维悬沙长期输运速度及其机理作了初步的计算分析,结果表明：在最大浑浊带,悬沙和水体长期输运有明显的差别;在描述悬沙长期输运时,二维悬沙长期输运速度比二维水体长期输运速度更合理;潮泵作用和垂向切变作用是造成两者差别的主要原因。     

Distribution of molluscan remains in the sediment of the Chukchi Sea and its vicinity, the Arctic

INTRODUCTIONInordertostudythemarinesedimentationoftheChukchiSeaandBeringSeaandgathertheinformationofpaleoceanographyandpaleoenvironment,theFirstChineseNationalArcticResearchExpeditionTeamcollectedbenthonicmolluscansamplesintheChukchiSea ,BeaufortSeaandBeringSeafromJuly 1sttoSeptember 9th ,1 999byicebreakerXuelong .ItwasnotonlythefirstsamplingthatChinesescientistscollectedmolluscaremainsinabove mentionedar eas,butalsooneofinvestigationsinasinglecruisewithhighersamplingrateandalotofb…     

Response of the suspended sediment transport system to continental shelf dynamics

Surface currents influenced by a wind-driven upwelling event in San Pedro Bay moved total suspended matter (TSM) confined to the inner shelf on 19 April 1978 seaward, so that by 27 April surface TSM had increased over the outer shelf. Near-bottom concentrations of TSM also increased across the shelf during this time. This is explained by sediment resuspended by large surface waves being advected from the inner shelf seaward by the mean flow after this flow had turned from southeasterly to southerly when upwelling ceased on 26 April. These complex shelf dynamics contribute to the off-shelf transport of mud to the slope and deep basins.     

浙江象山港海域悬沙浓度分布变化及其水动力影响分析

利用冬、夏两季象山港15个同步连续站和60个准同步大面站实测悬沙浓度数据,结合实测潮流、盐度等海洋水文资料,分析了象山港海域悬沙浓度变化规律。结果表明,象山港海域悬沙浓度分布具有较明显冬季大于夏季、大潮期大于小潮期以及湾口向湾顶逐渐减小的变化特征。这些特征主要受制于冬季高含沙量、低温、低盐的闽浙沿岸流与夏季高温、高盐、低含沙量的台湾暖流的交替作用和半月潮周期潮流动力变化的影响。在这种背景下,由于潮流动力作用,大小潮周期中底部沉积物与水体悬浮泥沙之间存在再悬浮与沉降的交换过程。     

海底峡谷的分类与识别研究进展

为更好地研究海底峡谷的形成、演化并充分开发利用海底峡谷,通过对国内外海底峡谷分类与识别有关研究成果的总结和归纳,综合考虑海底峡谷的多项因素,建立了一套新的分类体系,同时对海底峡谷的识别方法进行了概述分析。新建立的分类体系能够更好地满足海底峡谷的分类要求,海底峡谷识别方法优缺点的总结可为大规模海底峡谷识别提供支持。对海底峡谷分类与识别的研究综述将会为以后的研究以及相关海洋产业的发展提供支撑和帮助。