长江口南支二维潮流数模及其在太仓围滩工程中的应用

首先，建立了适用于长江口南支河段的水深平均二维定潮流数学模型。然后，采用１９９４年８月３次实测潮流过程资料，对该数学模型的流场、潮位过程及流速过程进行了验证计算，计算表明：该数学模型能较好地模拟南支河段的潮流运动，数模方法及处理适当，证精度较高。最后，应用该数学模型计算了南支河段内仓围滩工程对防洪及流场的影响，为该围滩工程可行性研究提供了论证依据。     

Numerical Simulation of Wind-Induced Motion in Suspended Sediment Transport

In regions with broad water surfaces such as lakes, reservoirs and coastal areas, the wind stress on the flow motion generates a significant impact. The wind stress is an unsteady force which makes numerical simulation difficult. This paper presents a two-dimensional (2-D) mathematical model of the impact of wind-induced motion on suspended sediment transport at Beijing's 13-Ling Reservoir. The model uses the Diagonal Cartesian Method (DCM) with a wetting-drying dynamic boundary to trace variations in the water level. The calculation results have been tested against in situ measurements. The measurements confirm the model's accuracy and agreement with the actual situation at the reservoir. The calculations also indicate that wind stress holds the key to suspended sediment transport at Beijing's 13-Ling Reservoir, especially when westerly winds prevail.     

河口水文学发展概况

河口区是河流与海洋之间的过渡区，河口水文学是涉及水文学、水力学、地理学、海洋学、河流学及生态学等的综合性学科。国外早已开展河口水文研究，并取得了许多研究成果。伏尔加河河口早在１７７７年即开始进行水文观测及科学实验，此外，莱茵河、马斯河、些耳得河、泰晤士河、塞纳河、密西西比河、哈得逊河及萨克拉门托河的河口水文研究也较为深入。河口水文学有研究水平在一定程度上体现了国家经济发展水平。本文阐述了河口水文学     

长江河口水环境现状及趋势分析

采用单项水质因子法，对长江河口实测水质资料进行分析，根据长江口水体质量特征，评价主要侧重于有机指标，选择了溶解氧（DO）、高锰酸盐指数（CODMn)、5日生化需氧量（BOD5）、氨氮（NH3－N）、亚硝酸盐氮（NO2－N）、硝酸盐氮（NO3－N）和总磷（TP），另外还选择了盐度指标氯化物（Cl^-)进行分析。结果表明河口江段呈现有机污染的特征，总磷、化学耗氧量和氨氮为要污染因子；河口江段断面水质目前状况尚可，但近岸水域水质明显劣中泓水质；汛期水质劣于非汛期水质；评价期内岸边水域落潮期水质劣于泓潮期水质，最后对长江河口未来水质变化的趋势进行了预测。     

浅析长江河口的界定

在介绍河口分类的基础上，分析了长江河口的形态特征、潮汐特性和水特点，根据《中华人民共和国法律大百科全书》中国际法对河口界线的阐述，结合《奥本海国际法》对河口问题的论述，按照我国现有法规的有关规定，针对长江河口的实际情况，对长江河口末端位置提出建设性的界定方案。     

坚持综合治理 开发长江河口

长江河口具有十分重要的区位优势和丰富的自然资源,但长期以来一直处于自然状态,严重地制约了河口地区社会经济的发展。随着国民经济的发展,长江口的整治即将进入实施阶段。由于每一局部工程的实施,都会对整个河口系统产生不同程度的影响。同时国民经济各部门对河口治理的权益见识也不尽一致。因此,当前尤其要强调坚持综合治理,统筹兼顾,才能使各个局部的整治工程,充分发挥其整体的效益,收到最佳的社会经济效益回报。     

长江河口控制站泥沙絮凝特性研究

基于2008-2014年逐月现场激光粒度仪(LISST)在长江口徐六泾的定点观测数据,分析了河口控制站徐六泾的悬沙絮凝特性,研究给出絮团粒径与有效密度及沉速的关系。统计表明絮团平均粒径变化范围20~120μm,比分散颗粒中值粒径(平均5.3μm)大一到两个数量级。絮团的分形维数主要在1.8~2.4,有效密度变化范围70~600kg/m~3,其随絮团增大呈减小趋势。洪枯季对比表明,洪季絮团沉降速度比枯季大18%,平均沉速分别为0.26mm/s和0.22mm/s,比以往估算得到的长江口浑浊带絮团沉速小。由此说明为更好认识流域到河口的泥沙输运过程,有必要针对长江河口不同区域进行分段的研究。     

长江河口北港河道泥沙特性及河床沙再悬浮研究

基于北港上段和下段以及南支河道三个站点的7天连续同步水沙观测数据(包括潮流、悬沙含量和表层沉积物样品),通过对不同时刻悬沙浓度、悬沙和沉积物粒径组成分析,以及基于沙量平衡的粒度谱计算,对长江口北港河道泥沙特性和河床沉积物再悬浮作用进行了研究.结果表明:北港上段河道落潮时水动力强于涨潮,单宽输沙量表现为净向海输沙;河床沉积物颗粒较粗,细砂和粉砂含量可达90％以上;近底层悬沙浓度在一个涨或落潮周期内可存在两个峰值;河床沉积物再悬浮作用落潮强于涨潮.     

CALCULATION MODELS FOR THE SUSPENDED SEDIMENT TRANSPORT RATE

The calculation accuracy of the suspended sediment transport rate relies on that ofthe vertical distribution of the particle concentration,the particle velocity distribution and thereference concentration.In view of the limitations of the previons formulas for both the velocityand the concentration distributions,general expressions are introduced to the calculation of sus-pended sediment transport rate.Based on these analyses,a simple and practical calculation modelis given in the present paper.     

NUMERICAL MODELING OF SUSPENDED SEDIMENT TRANSPORT IN CHANNEL BENDS

1. INTRODUCTION Due to the fact that three-dimensional (3D) numerical models are quite expensive to simulate flow and sediment transport processes, vertically-integrated two-dimensional (2D) models are extensively applied at present, even to the predictio…     

A VERTICAL 2-D NUMERICAL SIMULATION OF SUSPENDED SEDIMENT TRANSPORT

Numerical simulation of sediment transport and bed evolution has become an important technique in the sediment research. In this article,a numerical model of suspended sediment transport was proposed,which was established in the vertical σ coordinate for fitting the free surface and bottom. In the research of the sediment transport,the predominant factors were found to be the eddy diffusion,the settling velocity,the bed condition and so on. By the aid of the model in the article,the contribution of the Rouse parameter to the vertical profile of sediment concentration was clarified,which was identical to the theoretical results. In the comparison of the numerical results with laboratory data,the agreement between experimental data and numerical results was reached except for some data. And the possible reasons for the disagreement were discussed.     

NUMERICAL SIMULATION OF BED TOPOGRAPHY CHANGES INDUCED BY DEEP WATER NAVIGATION CHANNEL PROJECT IN THE YANGTZE ESTUARY

1 .　INTRODUCTIONWiththedevelopmentofindustriesintheYangtzeestuary ,moreandmoreprojects ,suchasportdevelopments ,waterwayconstruction ,landreclamationaswellascoastalprotectionworks,havebeenconductingintheestuary .Moredetailedknowledgeofthetidehydrodynamicsandsedimenttransportmechanisminthewaterisneededforconstructionandmanagementofthe projectsbe causeofthedifficultiesinmodelingthecharacter isticsoffinecohesivesedimentmovementandthecomplicatedflowsdrivenbyriverdischarge ,tide ,stormsurgeand…     

NUMERICAL SIMULATION OF THE TIDAL MOTION AND SUSPEND EDSEDIMENT TRANSPORT IN THE RADIAL SANDBANK AREA OF THE SOUTHERN YELLOW SEA

A coupled 2-D numerical model for hydrodynamic-sediment transport was established and applied to simulate the tides, tidal currents and sediment movement in the submarine Radial Sandbank area of the southern Yellow Sea.With a high-resolution topography dataset used in the model,the simulation reproduced a fine-structured current field and erosion-siltation distribution. The modeled results show that,in the area of Radial Sandbanks, reversing tidal current and seabed erosion occurs within troughs while tidal current with more rotary feature and deposition occurs above sandbanks,which indicates the tidal-induced formation of the Radial Sandbanks. During a tidal period, associating with the variation of current speed, erosion alternates with siltation. The seabed deformation depends on the relative strength of erosion and siltation in a tidal period.     

2-D NUMERICAL SIMULATION OF RADIONUCLIDE TRANSPORT IN THE LOWER YANGTZE RIVER

The assessment of the radiological impact of the liquid discharges from nuclear power plants is a major issue for the environmental protection. In this study, a numerical model for the radionuclide transport in the aquatic environment is built, based on the hydrodynamic equations, including the complete set of Saint-Venant equations, the sediment transport equations, with consideration of several different particle sizes and the deposition and erosion of the suspended sediments, and the radionuclide transport equations. The exchanges of radionuclides between water, suspended matter and bed sediments are described in terms of kinetic transfer coefficients. The model is used to simulate the transport of the radionuclides discharged from a planned nuclear power plant project to be sited along the lower Yangtze River. From the model results, one may see the detailed temporal-spatial evolution of the radionuclide contamination in the solution, in the suspended matter and in the bed sediments. The model can be used as a basic tool for studying the environmental impacts of the liquid discharges from nuclear facilities on a river system.     

EFFECT OF SUSPENDED SEDIMENT ON THE TRANSPORT AND TRANSFORMATION OF 4-NITROCHLOROBENZENE IN THE YELLOW RIVER

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A MATHEMATICAL MODEL FOR UNSTEADY SEDIMENT TRANSPORT IN NINGXIA REACH OF THE YELLOW RIVER

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CRITICAL UNIT STREAM POWER FOR SEDIMENT TRANSPORT

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＡＮＤＬＩＴＥＲＡＴＵＲＥＲＥＶＩＥＷＩｎｃｉｐｉｅｎｔｍｏｔｉｏｎｉｓａｓｐｅｃｉａｌｃａｓｅｏｆｓｅｄｉｍｅｎｔｔｒａｎｓｐｏｒｔ ,ａｎｄｔｈｅｔｒａｎｓｐｏｒｔｒａｔｅｏｒｃｏｎｃｅｎｔｒａｔｉｏｎｉｓｚｅｒｏｏｒａｓｍａｌｌｖａｌｕｅｔｈｅｎ .Ｗｉｔｈｔｈｅｅｘｃｅｐｔｉｏｎｏｆｐｒｏｂａｂｉｌｉｓｔｉｃａｎｄｒｅｇｒｅｓｓｉｏｎａｐｐｒｏａｃｈ ,ｓｅｄｉｍｅｎｔｔｒａｎｓｐｏｒｔｅｑｕａｔｉｏｎｃａｎｂｅｅｘｐｒｅｓｓｅｄｉｎｏｎｅｏｆｔｈｅｆｏｌｌｏｗｉ…     

EPISODIC SUSPENDED SEDIMENT TRANSPORT AND ELEVATED POLYCYCLIC AROMATIC HYDROCARBON CONCENTRATIONS IN A SMALL,MOUNTAINOUS RIVER IN COASTAL CALIFORNIA

Suspended sediment and organic contaminants were measured during a period of 2 years in the San Lorenzo River, central California, which discharges into the Pacific Ocean within the Monterey Bay National Marine Sanctuary, in an effort to quantify the potential environmental effects of storm events from a steep, mountainous coastal urban watershed. Most suspended sediment transport occurred during flooding caused by winter storms; 56% of the total sediment load for the 2‐year study was transported by the river during one storm event in January 2010. Concentrations of polycyclic aromatic hydrocarbons can exceed regulatory criteria during high‐flow events in the San Lorenzo River, and total annual polycyclic aromatic hydrocarbon load was on the order of 10 kg in water year 2010. These results highlight the importance of episodic sediment and contaminant transport in steep, mountainous coastal watersheds and emphasize the importance of understanding physical processes and quantifying chemical constituents in discharge from coastal watersheds on event‐scale terms. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.