复杂边界河道流速场的数值模拟

本文采用正交曲线拟合坐标来克服天然河道复杂几何边界给有限差分法带来的困难，采用物理分步法求解水流的控制方程，应用“运边界”技术追踪在非恒定流时，因水位变化引起的计算区域的变化。建立了天然河道非恒定流的计算模式，成功地模拟了具有复杂边界二维河道的流速场。     

重庆创宇化危品码头通航二维水流数值模拟

为了克服计算域边界起伏变化较大的问题,利用贴体正交曲线坐标系建立二维水流数值模型,模拟重庆创宇化危品码头河段通航水流条件,运用苟家沱至五步政河段的水面线、流场的流向及流速分布等实测资料进行验证,计算结果表明,二维水流数学模型的建立和数值计算方法合理,能较好的模拟实际河道的水流特性.     

用正交曲线网格及“冻结”法计算河道流速场

本文采用边界拟合正交曲线网格,来克服天然河道边界形状复杂及长宽比相差悬殊所带来的困难。在数值求解过程中介绍了用“冻结”技巧来处理动边界,使动边界计算问题简化成固定边界。本文在前人的弯道研究基础上对变换后的基本方程式作了修正,修正后的方程式可以考虑弯道水面横比降所引起的环流对垂线平均流速的影响。     

具有指定边界网格间距和正交性的BFC网格生成方法

边界拟合曲线坐标(BFC)网格生成的质量直接影响流场的数值模拟精度和收敛速度,而如何选取生成BFc网格的Possion方程右端调节因子P和Q,则关系到生成的BFC网格质量.本文提出了一种可以同时实现控制网格正交性和控制边界网格间距的BFC网格生成的新方法.该方法可任意控制生成的网格边界间距大小,同时,生成的BFC网格还具有边界及内部较好的正交性.应用实例的计算结果表明,该方法能够对复杂边界的单连通域或多连通域生成较理想的BFc网格,网格分布能够适应流动参数的变化.     

全隐式差分法求解河道平面二维恒定水流运动方程

本文针对河道平面形状窄长的特点，采用全隐式差分法求解河道平面二维恒定水流运动方程，网格划分为曲线正交网络，本文同时提出了一种适合于复杂河道边界的曲线正交网格产生办法．实际计算表明，全隐式方法精度较高，且基本无条件稳定，在普通微机上运行，计算速度也是实际应用时可以接受的     

河流平面二维水流数学模型在抚河中的应用

本文提出了天然河道平面二维水流流场计算的一种通用数学模型,该模型克服了天然河道边界形状复杂、长宽尺度相差悬殊和由于水位波动引起计算边界变化等困难。应用该模型对抚河中游柴埠口至焦石坝河段洪水与中水流场进行了数值计算。计算结果表明,该模型具有较好的数学特性。     

支流河口水沙运动的二维数学模型研究

本文建立了一个支流河口水沙运动的二维数学模型.采用贴体正交曲线坐标克服了干支流汇合处河道边界形状复杂的困难，给出了正交曲线坐标系下二维全沙模型的基本方程及数值计算方法.以长江上游的嘉陵江河口为例，分析了支流河口河段水沙特性及浅滩成因，模拟了汇合口河段流场及泥沙冲淤分布，计算值与实例值吻合良好.为支流河口浅滩演变及整治研究提供了一种新的模拟方法.     

支流河口水沙运动的二维数学模型研究——以长江上游的嘉陵江河口为例

本文建立了一个支流河口水沙运动的二维数学模型．采用贴体正交曲线坐标克服了干支流汇合处河道边界形状复杂的困难，给出了正交曲线坐标系下二维全沙模型的基本方程及数值计算方法．以长江上游的嘉陵江河口为例，分析了支流河口河段水沙特性及浅滩成因，模拟了汇合口河段流场及泥沙冲淤分布，计算值与实例值吻合良好．为支流河口浅滩演变及整治研究提供了一种新的模拟方法．     

正交曲线网格在导流明渠模拟中的应用

由于在天然河道中修建导流明渠后,过流边界比较复杂,建立数学模型时划分网格难度较大,因此对于明渠水流的数值模拟研究尚不多见.采用非结构三角形网格能较好地划分复杂的计算区域,但对于导流明渠这类人工开挖的规则边界,地形插值后在渠道边坡上形成锯齿状地形,导致边界附近的水流模拟失真.采用局部连续的正交曲线网格划分计算区域,同时保证网格的贴体与良好的正交性,且能较精确地模拟人工开挖边坡,保证计算的稳定性与精度.建立了用于模拟导流明渠流场的平面二维水流数学模型,采用有限差分法求解水深积分方程.数值模拟结果与物理模型测量结果吻合较好,表明建立的数学模型能合理地模拟明渠内的水流.     

正交曲线网格在导流明渠模拟中的应用

由于在天然河道中修建导流明渠后,过流边界比较复杂,建立数学模型时划分网格难度较大,因此对于明渠水流的数值模拟研究尚不多见.采用非结构三角形网格能较好地划分复杂的计算区域,但对于导流明渠这类人工开挖的规则边界,地形插值后在渠道边坡上形成锯齿状地形,导致边界附近的水流模拟失真.采用局部连续的正交曲线网格划分计算区域,同时保证网格的贴体与良好的正交性,且能较精确地模拟人工开挖边坡,保证计算的稳定性与精度.建立了用于模拟导流明渠流场的平面二维水流数学模型,采用有限差分法求解水深积分方程.数值模拟结果与物理模型测量结果吻合较好,表明建立的数学模型能合理地模拟明渠内的水流.     

河道温度及浓度场的平面二维数值模拟

 立了河道水流、温度及浓度输运的水深平均平面二维数值模拟模型，由模拟水流、温度及浓度和紊流3个子模型组成。该模型在计算定解条件 模型参系数取值、河道岸边界和动边界模拟以及水流自动调整计算思想等方面进行了适用可行的处理。应用该模型进行了试验室空腔水槽温度和含沙量场以及长江口南支河段温排水及盐水入侵的数值模拟计算，证明了模型的可行性和适用性。     

黄河流域省界水环境质量状况及水污染特点

根据 1999年省界水体水质监测资料 ,采用单因子评价及污染指数计算等方法 ,评价分析了黄河流域省界水体环境质量状况及水污染特点 ,结果表明 :大部分省界河段受到程度不同的污染 ,水体功能降低 ,主要污染物为耗氧有机物。     

High-resolution flood modeling of urban areas using MSN_Flood

Although existing hydraulic models have been used to simulate and predict urban flooding, most of these models are inadequate due to the high spatial resolution required to simulate flows in urban floodplains. Nesting high-resolution subdomains within coarser-resolution models is an efficient solution for enabling simultaneous calculation of flooding due to tides, surges, and high river flows. MSN_Flood has been developed to incorporate moving boundaries around nested domains, permitting alternate flooding and drying along the boundary and in the interior of the domain. Ghost cells adjacent to open boundary cells convert open boundaries, in effect, into internal boundaries. The moving boundary may be multi-segmented and non-continuous, with recirculating flow across the boundary. When combined with a bespoke adaptive interpolation scheme, this approach facilitates a dynamic internal boundary. Based on an alternating-direction semi-implicit finite difference scheme, MSN_Flood was used to hindcast a major flood event in Cork City resulting from the combined pressures of fluvial, tidal, and storm surge processes. The results show that the model is computationally efficient, as the 2-m high-resolution nest is used only in the urban flooded region. Elsewhere, lower-resolution nests are used. The results also show that the model is highly accurate when compared with measured data. The model is capable of incorporating nested sub-domains when the nested boundary is multi-segmented and highly complex with lateral gradients of elevation and velocities. This is a major benefit when modelling urban floodplains at very high resolution.     

International Rivers as Boundaries

Abstract

International rivers serve a number of purposes, the most obvious are the navigational and non-navigational uses. Less noticed is the fact that international rivers are also used to delimit boundaries between nations. The immediate question that would arise is: Where are such boundaries actually drawn across the river? Boundaries, however, are established by treaties and the answer to this question is often included in the interpretation of treaties delimiting such water boundaries, taking into account the special characteristics of the international river. Indeed, this has been the case regarding the boundaries across the Chobe river between Botswana and Namibia. Determining where such boundaries lie would result in deciding to whom a disputed Island, the Kasikili/Sedudu, belongs. In a praiseworthy step, the two countries agreed to take their dispute over the Island, after failure to resolve it through negotiations, to the International Court of Justice. This paper discusses the uses of international rivers as boundaries, and reviews the dispute between Botswana and Namibia, and the decision of the Court thereon.     

河道调整研究现状及其对黄河下游游荡型河道调整的启示

系统梳理了河道调整研究现状,全面论述了与冲积河流调整相关的河相关系、不同边界下河道调整过程、冲积河流线性理论的研究现状及发展动态.新形势下黄河下游游荡型河道调整应重点研究水沙变化与有限控制边界对河道调整的耦合效应、河道断面自调整数理分析中断面形态假定、有限控制边界条件下游荡型河流主槽摆动幅度和频率等问题,这不仅有助于加...     

A 2-D HYDRODYNAMIC MODEL FOR THE RIVER, LAKE AND NETWORK SYSTEM IN THE JINGJIANG REACH ON THE UNSTRUCTURED QUADRANGLES

The main river,the Dongting Lake and river networks in the Jingjiang reach of the Yangtze River constitute a complex water system,for which a full 2-D hydrodynamic model is established instead of the traditional 1-D or compound models for simulation of such complex systems,based on the latest developments of computer technologies and numerical methods.To better handle irregular boundaries and keep the computation cost well in a reasonable limit,unstructured grids of moderate scale are used. In addition,a dynamic boundary tracking method is proposed to simulate variable flow domains at different floods,especially,when the moderate scale gird can not describe flows in narrow river-network channels at low water levels.Theθsemi-implicit method and the Eulerian-Lagrangian Method(ELM)are adopted,which make the model unconditionally stable with respect to the gravity wave speed and Courant number restrictions.Properties and efficiency of the model are discussed,and it is concluded that the new model is robust and efficient enough for the simulation of a big,complex water system.Validation tests show that the simulation results agree well with field data.It takes about 0.96 h to complete the computation of a 76 d flood,which indicates that the model is efficient enough for engineering applications.     

AUTOMATIC DELINEATION OF FUNCTIONAL RIVER REACH BOUNDARIES FOR RIVER RESEARCH AND APPLICATIONS

The river reach is a pervasive term within contemporary river research and applications. Yet, despite its prevalence, there is a notable lack of consistency in its definition. This paper identifies the presence of two broad types of reach definition within the academic literature, operational and functional, and argues that a functional definition is more suitable for applications within river research and management. A range of sequence zonation algorithms that were originally derived for geological well‐log analysis were compared for their ability to automatically identify functional reach boundaries. An analysis of variance‐based global boundary hunting algorithm was identified as the most suitable. To demonstrate the potential practical applications of automatic reach delineation methods, two case studies where functional reach boundaries have been identified were described: first, in a sequence of predicted sediment transport capacities for use in a reach‐based sediment transport model; and second, in a sequence of RHS Habitat Quality Assessment scores for identification of lengths of channel in need of habitat restoration efforts. Finally, the paper discusses how this type of functional reach identification procedure might be applied in other areas of river research and applications and how a multivariate version of a statistical zonation algorithm might prove useful in facilitating integrated catchment management by identifying reach boundaries common across all variables of interest in the system. Copyright © 2011 John Wiley & Sons, Ltd.     

黄河兰州段防洪及渠化河宽的模型试验与数值计算

针对黄河兰州段的防兴及渠化问题，在对河道地形、河相关系、水流河床演变进行分析后，确定了河道整治试验的重要参数，即洪水最小整治河宽。在此基础上，对该河段进行了模型人数值计算，试验及计算结果与原型河段实测资料吻合较好。     

Highlighting the ‘Multiple’ in MSPs: The Case of Cerro Chapelco,Patagonia, Argentina

Mainstream opinions put forward the idea that changes in water policies should be moving toward Integrated Water Resources Management at the level of the river basin (or watersheds). For its implementation, participation by river basin organizations (river basin authorities, river basin committees, communities of users, multi-stakeholder platforms, etc.) and by stakeholders is promoted. Multi-Stakeholder Platforms (MSPs) are presented as neutral spaces for negotiations in order to solve water conflicts among different (multiple) actors, who are all invited to participate in the discussion. Evidence from this case study suggests that even where water is put forward as the main issue to be tackled, in the background there may be far more sensitive issues at stake that shape the arenas of negotiation of policy design and implementation. MSPs can be used to bring to the fore issues that are easy to address, but can also be the background for wider social and political complexities. This is pursued using technical language to justify political definitions of boundaries, stakeholders and processes of participation. The ‘Watershed as a unit of planning’ approach is also presented as a neutral way of using a technical definition to set the boundaries for resource management. However, this study shows that the definition of boundaries is not necessarily as natural as it appears but is much more of a political decision that defines which resources are involved and which actors are considered or left out. The ‘multiple’ in MSPs is not only about ‘stakeholders’, but the different constructions of boundaries, scales and political interests, which include and exclude stakeholders. In the implementation of an MSP, the Multiple is rhetorical and not a representation of realties.