Mathematical model for flood routing in Jingjiang River and Dongting Lake network

The main stream of the Yangtze River, Dongting Lake, and the river network in the Jingjiang reach of the Yangtze River constitute a complex water system. This paper develops a one-dimensional (1-D) mathematical model for flood routing in the river network of the Jingjiang River and Dongting Lake using the explicit finite volume method. Based on observed data during the flood periods in 1996 and 1998, the model was calibrated and validated, and the results show that the model is effective and has high accuracy. In addition, the one-dimensional mathematical model for the river network and the horizontal two-dimensional (2-D) mathematical model for the Jingjiang flood diversion area were coupled to simulate the flood process in the Jingjiang River, Dongting Lake, and the Jingjiang flood diversion area. The calculated results of the coupled model are consistent with the practical processes. Meanwhile, the results show that the flood diversion has significant effects on the decrease of the peak water level at the Shashi and Chenjiawan hydrological stations near the flood diversion gates, and the effect is more obvious in the downstream than in the upstream.     

湖泊-河网耦合水动力水质模型研究

根据太湖地区水系复杂、湖泊众多、河道水流方向复杂多变且受到人为干扰的特征,基于一维河网水质模型,二维湖泊水质模型,采用有限控制体积法获得离散的水动力学和水质模型控制方程,通过河网与湖泊连接断面上河流的流量、水位、水质与湖泊的流速、水位和水质耦合求解,解决了河网湖泊水质模型的耦合,并将闸站控制对河流湖泊水动力水质影响过程进行了时间空间的线性化处理,以边界条件方式将闸站控制带入模型代数方程中进行统一求解,建立了适合于太湖流域的湖泊河网耦合水动力水质模型.采用太湖典型流域河网区2007年实测水文水质资料对耦合模型进行率定和验证.结果表明,模型计算值与实测资料吻合较好.该模型适用于复杂湖泊-河网区的水动力和水质变化的模拟和研究.     

Development and application of a eutrophication water quality model for river networks

The Preissmann implicit scheme was used to discretize the one-dimensional Saint-Venant equations, the river-junction-fiver method was applied to resolve the hydrodynamic and water quality model for river networks, and the key issues on the model were expatiated particularly in this article. This water quality module was designed to compute time dependent concentrations of a series of constituents, which are primarily governed by the processes of advection, dispersion and chemical reactions. Based on the theory of Water Quality Analysis Simulation Program （WASP） water quality model, emphasis was given to the simulation of the biogeochemical transformations that determine the fate of nutrients, in particular, the simulation of the aquatic cycles of nitrogen and phosphorus compounds. This model also includes procedures for the determination of growth and death of phytoplankton. This hydrodynamic and water quality model was applied to calculate two river networks. As illustrated by the numerical examples, the calculated water level and discharge agree with the measured data and the simulated trends and magnitudes of water quality constituents are generally in good agreement with field observations. It is concluded that the presented model is useful in the pollutant control and in the determination of pollutant-related problems for river networks.     

复杂河网水系油粒子模型开发及溢油污染模拟

近年来,油粒子模型在海洋、海湾等水体的二、三维溢油数值模拟中获得广泛应用.然而,河网地区的水流模拟通常采用一维水动力模型,无法根据模型预测结果判断油粒子运动至河网节点后的流动方向,导致现有油粒子模型不能应用于河网水系溢油污染模拟.本研究针对水网地区溢油输移特征,通过定义河网节点出流河道流向因子,判断油粒子运动至河网节点...     

DISTRIBUTED WATER BALANCE WITH RIVER DYNAMIC-DIFFUSIVE FLOW ROUTING MODEL

This article focuses on the application of coupling both river dynamic and river diffusive modeling techniques that can be used with distributed water balance model. In an upstream watershed, both overland and river diffusive flows are routed by diffusive wave approximation of the free surface flow equations. In river downstream reaches, the river dynamic flow is routed by one-dimensional dynamic wave equations (full dynamic St. Venant equations with lateral flow). The developed model is applied in a part of Arakawa River basin, Kanto area, Japan. The geographic data of river cross sections could be accurately represented by an 11-point cross-section approximation. The effects of both the grid size and lateral flow on the simulated results of the river dynamic flow model were studied. The grid size should be greater than the average width of the river cross-sections. The lateral flow from small drainage systems has significant effects on the simulated results using the river dynamic flow model. The simulated results show good and acceptable agreements with the observed flow discharges and water depths. Both the river discharge and water depth at any location of river network of compound channels with one/two complex floodplains could be correctly estimated.     

基于水文水动力学耦合的洪水预报模型研究及应用

为了提高下垫面变化剧烈流域的洪水预报精度,在传统流域水文模型的基础上耦合水动力学模型,建立水文水动力耦合洪水预报模型。首先利用水文模型获得某一断面的流量过程作为水动力学模型的边界条件;之后利用一维水动力学模型进行河道洪水演进计算,推求流域出口断面的流量过程;最后以烟台市外夹河流域为例进行验证。结果表明,所建水文水动力耦合模型模拟的产流合格率较高,流量过程与实测值吻合,在一定程度上弥补了集总式水文模型不能考虑河道内复杂水流运动的不足,因此对具有复杂水文、水力条件的流域的洪水预报具有重要的指导意义。     

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.     

基于PINNs的圣维南方程组数据同化方法

为提高河道水位流量数据同化的智能化水平,基于物理信息神经网络(PINNs)提出了圣维南方程组的数据同化方法。采用双输出网络结构解决双输出方程组的同化问题,以模拟的实测数据作为边界条件和初始条件,通过消融试验验证网络中加入时空映射缩放和平衡权重系数对同化模型的有效性,以及所提出同化方法在部分测值缺失情况下的鲁棒性。结果表明,一维非恒定流圣维南方程组的数据同化结果与Preissmann四点隐式差分法结果一致,且随着同化断面数量的增加,所获得的同化精度也稳步提升;基于PINNs的圣维南方程组数据同化方法有效,对非恒定流模拟具有较强的适应性。     

RESEARCH ON HYDRODYNAMIC AND WATER QUALITY MODEL FOR TIDAL RIVER NETWORKS

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＰｌａｉｎｒｉｖｅｒｎｅｔｗｏｒｋａｒｅａｉｓａｌｗａｙｓｔｈｅｒｅｇｉｏｎｗｉｔｈｌｏｗｅｒｔｏｐｏｇｒａｐｈｙ ,ｈｉｇｈｄｅｖｅｌｏｐｅｄｃｉｔｉｅｓａｎｄｌａｒｇｅｑｕａｎｔｉｔｙｏｆｐｏｐｕｌａｔｉｏｎ ,ｉｎｃｌｕｄｉｎｇｓｏｍａｎｙｌａｋｅｓ,ｒｉｖｅｒｎｅｔｗｏｒｋｓ.Ｔｈｉｓｋｉｎｄｏｆａｒｅａｉｓｓｔｒｏｎｇｌｙｉｎｆｌｕ ｅｎｃｅｄｂｙｔｉｄａｌ,ａｎｄｆｌｏｏｄｏｃｃｕｒｓｆｒｅｑｕｅｎｔｌｙ .Ｈｙｄｒｏｄｙ ｎａｍｉｃｓｉｔｕａｔｉｏｎｏｆｔｉｄａｌ…     

NUMERICAL SIMULATION FOR SHALLOW FLOW AND POLLUTANT DISPERSION BASED ON QUAD-TREE MESHES

1. INTRDUCTION Natural flow domains have complicated boundary configurations, which may themselves strongly influence the interior flow patterns.Sometimes, high-gradient zones and local areas which are relatively important in some problems are included in…     

一维潮流与含氯度耦合数学模型及其应用

针对东江三角洲的实际情况,建立一维潮流与含氯度耦合数学模型,通过对东江下游及其三角洲供水水源工程8个基本布置方案的对比分析,定量计算不同方案对水动力条件、咸潮界的影响。结果表明:该模型能较好地模拟潮流与含氯度的变化,可为东江三角洲河网区河道治理、城市供水工程建设等相关问题的研究提供科学依据及技术支撑。     

一维河网非恒定流及悬沙数学模型的节点控制方法

本文的一维河网非恒定流及悬沙数学模型，是根据以一维圣维南方程组，悬沙非平衡输运方程及水位、含沙量节点控制法而建立。首先，利用单一河流有限差分方程组转换形式和节点处质量、能量守恒性，写出所有节点的水位控制方程组。求解此不规则稀疏矩阵方程组得到得有节点的水位，再由单一河流非恒定流的求解方法可获得所有单一河流的断面水位和流量。基于水注的节点水位控制法，本文提出了节点悬沙控制法。假设节点处冲刷或淤积较小，所有节点的含沙量控制方程组可通过输沙量守恒方程用矩阵形式写出。求解此不规则稀疏矩阵方程组，得到所有节点处的含沙量。所有单一河流断面处的含沙量通过单一河流悬沙输运的求解方法获得。本文介绍的模型适用于各种河网类型。作为检验，该模型成功地应用于珠江三角洲流域河网水流及悬沙的数值计算。     

浐灞河下游河段水质模拟研究

根据浐灞河下游河段水质系统的状况,从管理角度和水质模型的空间维数来考虑,选取河流一维稳态水质模型,依据大量的实测数据率定降解系数,设定现状调查排放源、许可固定排放源与规划排放源3种工况,模拟浐灞河下游河段沿程各断面水质影响变化。通过对比3种工况对水质影响关系,得出在现状调查排放源和许可固定排放源条件下,水质受到污染;在规划排放源条件下,呈现出较好的水质状况。研究结果为河道的水环境管理提供了依据。     

城市雨洪综合模拟方法及应用

为综合模拟城市雨洪和分析其对区域内涝的影响,在Open MI异构模型集成平台上动态耦合河网水文水动力模型和城市排水管网水力模型,以上海14个水利分片之一的淀北片为例,建立了淀北片雨洪耦合模型,并应用此模型分析了不同雨潮组合对淀北片区域内涝的影响。淀北片雨洪综合模拟计算结果表明,雨洪综合模拟较真实地反映了感潮河网城市地区的内涝情况,可为城市防洪除涝工作提供参考。     

WASP5水质模型在平原河网区的应用

以平原河网区水环境为研究对象,选择了WASP5系统作为平原河网水质模拟的基本工具,针对WASP5系统自带的DYNHYD5水动力模型功能的局限性,以及平原河网水力调控系统复杂的特征,选择了具有产汇流模拟、闸坝控制模拟及河网水流模拟等功能的三级联解平原河网水动力模型。通过利用C++语言编程,实现了三级联解平原河网水动力模型与WASP5水质模型的耦合,使之可以应用于平原河网水环境的模拟。并把研究成果运用到实际引调水工程中去,模拟引调水工程中不同实施方案下的环境效益,为引调水工程实施方案的确定提供了理论依据。     

洪水与风暴潮共同作用下的溃堤洪水一维、二维耦合模型及应用

为了解决复杂条件下河道洪水漫堤、溃堤和潮水倒灌的问题,建立了在洪水和风暴潮共同作用下的天然河道漫溃堤洪水在防洪保护区的一二维水动力耦合模型。在兼顾计算效率和精度的基础上,分区剖分网格,设置合理的网格面积;根据植被和地物的不同,分区设置糙率;通过宽顶堰的方式将河道一维模型和防洪保护区二维模型进行侧向耦合;采用基于侵蚀的渐变溃破坏方式模拟河道溃堤过程,实现了河道上游发生洪水和下游遭遇外海风暴潮的复杂情况下精细化模拟。实例研究表明,所建模型可灵活处理复杂多变的水力条件,模拟结果合理可靠,可为防汛部门制定决策提供有力的科学依据。     

UNIFIED MODEL FOR SPLASH DROPLETS AND SUSPENDED MIST OF ATOMIZED FLOW

In this article, the unified mathematical model for splash droplets and suspended mist of atomized flow was established, which classifies the atomized sources into the splash source and the suspended source. For the splash source, the Lagrangian method was used to simulate the random motion of splash water droplets, and for the suspended source the theory of air-water two-phase flow was used to simulate the mist flow moving in particle clouds. The rainfall intensity of the atomized flow was obtained by summarizing the rainfall intensities relative to the above two types of atomized sources. Both experimental data and prototype observation data were used for the verification of the mathematical model. For both the distribution of rainfall intensity, and the outer edge of the atomized flow, the simulation results are in agreement with the experimental data or prototype observation data.     

一种基于Google Earth影像的河道地形数据提取方法

为解决无实测资料地区的河道地形数据获取问题,提出了一种基于Google Earth影像提取河道地形数据的方法,利用该方法提取了鉴江流域的河道地形数据并将其应用于水动力模型的构建。结果表明:利用该方法提取的河道地形数据所构建的水动力模型,其模拟过程与实际过程基本一致,其中模拟的最大、最小流量与实测对应的最大、最小流量的相对误差分别为14.3%和7.8%,流量模拟的整体相对误差为13.2%;模拟的最高、最低水位与实测对应的最高、最低水位的相对误差分别为5.5%和3.9%,水位模拟的整体相对误差为5.2%;基于Google Earth影像提取河道地形数据是解决无河道地形资料地区的一种便捷且行之有效的方法。     

向家坝水利枢纽下泄非恒定流的数值模拟

采用四点隐格式和改进的求解方法建立了向家坝枢纽下游145 km河段的非恒定流数学模型,通过2005年实测的枯、中、洪水过程对模型进行验证。应用该模型模拟了向家坝日调节下泄非恒定流的传播过程,分析了枢纽下游非恒定流的传播规律。模拟结果表明枢纽下游河段产生附加比降,水位~流量关系呈绳套状,且非恒定波发生横向变形。     

SIMULATION OF LOW-CONCENTRATION SEDIMENT-LADEN FLOW BASED ON TWO-PHASE FLOW THEORY

Low concentration sediment-laden flow is usually involved in water conservancy, environmental protection, navigation and so on. In this article, a mathematical model for low-concentration sediment-laden flow was suggested based on the two-phase flow theory, and a solving scheme for the mathematical model in curvilinear grids was worked out. The observed data in the Zhang River in China was used for the verification of the model, and the calculated results of the water level, velocity and river bed deformation are in agreement with the observed ones.