微观建模在城市给水管网系统中的实践

给水管网系统动态建模是自来水公司实现科学管理、提高效益、提高服务水平的重要手段.以天津市给水管网系统建模为例,详细地阐述了给水管网系统微观建模的理论与方法.     

建立给水管网微观动态水力模型标准方法研究

阐述了水司建立给水管网微观动态水力模型的必要性 ,提出了一套适合我国国情的给水管网建模标准方法。这一方法将有助于我国给水管网建模工作走上正规化和科学化的道路。该方法已经成功地应用于上海市。     

给水管网建模中建立计算机供水系统管网图形和在地形图上划定节点流量区域的方法

本文提出了给水管网建模过程中，建立计算机供水管网图形及在地形图上划定节点流量区域的方法，实践证明这一方法应用于大型的复杂的城市供水管网建模是成功的，具有较大的应用价值。     

城市给水管网的计算方法及应用

应用有限元，线性化处理及优化方法，编写管网平差计算的ＦＯＲＴＲＡＮ程序。该程序可用于环状网或树状网有单水源或多水源的各种情形，且不受管网是平面的或立体的及环数多少的限制。     

山区城市给水管网规划实例

通过对一个山区城市给水管网规划实例的分析，提出在山区给水中应充分利用高差自流供水，并按照地形高差对给水管网进行分区，加压供水的区块与重力流供水的区块管网应相互隔断，同时，对长期运行在高水压下的管网，宜设置减压措施。     

分形理论在城市给水管网布置中的应用

通过对分形理论和给水管网特点的研究,建立了一种新的定量描述给水管网空间分布状态的评价指标--管网覆盖度和管网覆盖深度。采用盒计数法计算给水管网规划布置的分形维数,将给水管网的规划布置由定性分析改为定量分析,从而为给水管网的定线和布局做出合理的指导,使给水管网的平面布置更加科学可靠。     

城市给水管网状态模拟方法探讨

从微观和宏观模型两个方面阐述了给水管网状态模拟技术的最新进展。通过采用参数校正,采样定位,对控制元素的模拟等方法,能够使微观模型达到较高的精度;经验与理论公式相结合的方法可以弥补宏观模型的不足;采用神经网络方法对模型的不稳定情况进行分析,从而得出状态模型的不准确程度;采用模型驱动的神经网络方法建立给水管网宏观模型,建成的模型具有更好的学习能力和容错能力。     

计算机辅助设计动态给水管网模型

运用计算机建立给水管网动态模型不但能完成静态的数据分析和系统设计 ,还可以实现对给水管网的动态分析和仿真 ,从而实时获取管网系统在不同供水需求以及极端用水条件下的状况。讨论了国内现有的管网模型和应用情况 ,并详细介绍了国外专业软件WaterCAD。     

城市给水管网实用优化分区探讨与实践

提出了给水管网实用优化分区的概念。在水力模拟计算的基础上,结合我国城市给水管网系统实际情况,对城市给水管网进行分区,然后在分区的基础上再通过水力模拟计算进一步确定其合理性并完善方案。阐述了给水管网实用优化分区步骤,包括选择区域系统阶层数、划定区域规模、确定进水点数目和位置、划定区域边界等。将其应用于某大城市实际管网,取得了良好的效果。     

给水管网微观模型中节点流量在线预测计算方法研究

阐述了研究区域时总用水量数据整理、时总用水量预测、制作用水模式曲线、节点流量预测值计算 ,建立了给水管网微观模型中节点流量在线预测计算方法 ,并在实践中加以验证。     

城市给水管网三维水压面的绘制

基于管网水力计算成果 ,通过管网投影区域的四边形网格插值 ,利用OpenGL图形库 ,进行了管网三维水压面的绘制 ,可用作给水管网设计、运行和优化调度时的信息表达工具     

BP神经网络用于给水管网模拟试验时的构造参数设计

介绍了BP神经网络的基本原理 ,并结合一个城市给水管网的模型试验 ,对神经网络技术应用中涉及的构造参数 (三层BP神经网络模型中隐含层和输出层的节点数 )选择进行了研究     

城市供水管网普查技术方法初探

对城市庞大的供水管网进行普查是一项复杂的系统工程。通过对武汉市武昌区供水管网的普查工作 ,探索和总结了一套较有成效的工作方法和程序。     

Pressure Management Model for Urban Water Distribution Networks

A technique for leakage reduction is pressure management, which considers the direct relationship between leakage and pressure. To control the hydraulic pressure in a water distribution system, water levels in the storage tanks should be maintained as much as the variations in the water demand allows. The problem is bounded by minimum and maximum allowable pressure at the demand nodes. In this study, a Genetic Algorithm (GA) based optimization model is used to develop the optimal hourly water level variations in a storage tank in different seasons in order to minimize the leakage level. Resiliency and failure indices of the system have been considered as constraints in the optimization model to achieve the minimum required performance. In the proposed model, the results of a water distribution simulation model are used to train an Artificial Neural Network (ANN) model. Outputs of the ANN model as a hydraulic pressure function is then linked to a GA based optimization model to simulate hydraulic pressure and leakage at each node of the water distribution network based on the water level in the storage tank, water consumption and elevation of each node. The proposed model is applied for pressure management of a major pressure zone with an integrated storage facility in the northwest part of Tehran Metropolitan area. The results show that network leakage can be reduced more than 30% during a year when tank water level is optimized by the proposed model.     

Design of Water Distribution Network for Equitable Supply

Water shortage is experienced in different parts of the world in different magnitude. In certain countries, water deficit is a regular phenomenon and in some other countries it happens for a short duration, due to failure of any component in the system. Shortage of water at source can be best tackled by distributing the available water equally among the consumers. This paper deals with the design of water distribution network capable of equitable supply during shortage in addition to the satisfactory performance under non-deficit condition. Performance of a typical water distribution network, with shortage of water at source is illustrated in detail. Head dependent outflow analysis with extended period simulation, is used to determine the actual supply from each node to consumers. Relationship between duration of supply and volume available at source as well as supply from each node are established for understanding the behaviour of network under low supply situation. A term “inequity” which is the maximum difference in supply demand ratio among different consumers is presented. This is based on the actual performance of the network instead of surrogate measures, generally used for reliability. It is illustrated that the maximum “inequity” in supply in a network during the entire duration of supply can be estimated with single analysis. Design of a water distribution network, duly considering equity in addition to the cost minimization and minimum head requirement is presented. Genetic Algorithm is used for solving this multi objective problem. The solution technique is illustrated using two benchmark problems, namely two loop network and Hanoi network. Results show that considerable improvement in equitable supply can be achieved with additional investment on pipes above the least cost solution. Hence it is better to design networks duly considering deficit condition for better reliability. It is also illustrated that it will be difficult to improve equity beyond a limit for a given network, through selection of different pipe diameters.     

Nodal Analysis of Urban Water Distribution Networks

There are three methods for analysing the flow and pressure distribution in looped water supply networks (the loop method, the node method, the pipe method), accounting for the chosen unknown hydraulic parameters. For all of these methods, the nonlinear system of equations can be solved using iterative procedures (Hardy–Cross, Newton–Raphson, linear theory). In the cases of the extension or the rehabilitation of distribution networks, the unknown parameters are the hydraulic heads at nodes, and the nodal method for network analysis is preferred. In this paper, a generalised classic model is developed for the nodal analysis of complex looped systems with non-standard network components and the solvability of new problems, along with the determination of the pressure state in the system. In addition, this paper exhibits a different approach to this problem by using the variational formulation method for the development of a new analysis model based on unconditioned optimisation techniques. This model has the advantage of using a specialised optimisation algorithm, which directly minimises an objective multivariable function without constraints, implemented in a computer program. The two proposed models are compared with the classic Hardy–Cross method, and the results indicated a good performance of these models. Finally, a study is performed regarding the implications of the long-term operation of the pipe network on energy consumption using these models. The new models can serve as guidelines to supplement existing procedures of network analysis.     

Smart Water Network Modeling for Sustainable and Resilient Infrastructure

Urbanization can significantly increase the load on aging, inefficient and already strained sewer infrastructure, resulting in catastrophic pipe failure, unwanted spillage, property damage, and serious threat to public health. Urbanization can also dramatically alter the natural water cycle, resulting in diminished water quality, increased frequency and severity of flooding, channel erosion and destruction of aquatic habitat. Recent advances in smart water network (SWN) modeling technology have played a crucial and growing role in addressing these challenges. SWN technology has equipped practicing engineers with a comprehensive set of analytical decision making tools designed to help them preserve structural integrity, manage and reduce the risks of sewer overflow and urban runoff, improve resiliency and keep their urban drainage networks operating well into the future. These advances propel routine conveyance system analysis from basic planning and design to two-dimensional surface/subsurface flow modeling, real-time operation and control, analytical risk-based asset integrity and condition assessment, and optimal selection and placement of green infrastructure based on cost and effectiveness. SWN is providing critically needed support to federal, state, and local agencies and watershed practitioners — not only in optimizing their integrated water management and adaptation strategies, but in ensuring sustainable drainage, addressing environmental quality restoration and protection needs in urban and developing areas, and improving communities’ resiliency. It is also within the grasp of utilities of all sizes, but they need to seize the opportunity.     

Identification of Critical Pipes for Water Distribution Network Rehabilitation

The water distribution network needs to be rehabilitated when the network is unable to perform the desired function. In this study, a methodology is developed to identify the critical pipes in the water distribution network for its rehabilitation by using four network reliability metrics: supply shortage, pressure decline, energy loss per unit length, and the hydraulic uniformity index. These metrics consider different aspects of reliability of the water distribution network using pressure-dependent analysis to calculate the overall criticality of the pipes. In contrast to the conventional reliability index, the present study uses both the normal and abnormal conditions at nodes (fire demand) and pipe (pipe failure) and thus, provides more balance reliability metrics for the network. The literature shows that the node and pipe level metrics have been used separately, whereas in this study both the node and pipe level metrics are combined to develop the present methodology. The methodology is applied to four different water distribution networks, including one typical realistic water distribution network, the data for which is adopted from literature. The results show that the methodology can identify the critical pipes successfully to prioritize the water distribution network rehabilitation and found to be simple in implementation for practicing professionals. The results further show that the critical pipes are found to be located from the source on the paths that do not have a loop or around the nodes of higher demand. The study might also be useful for the extension plan of a water distribution network along with strengthening the deficient nodes/ pipes of the network.