An Accurate Leakage Localization Method for Water Supply Network Based on Deep Learning Network

In the water supply network, leakage of pipes will cause water loss and increase the risk of environmental pollution. For water supply systems, identifying the leak point can improve the efficiency of pipeline leak repair. Most existing leak location methods can only locate the leak point approximately at the node or pipe section of the pipe network but cannot locate the specific location of the pipe section. This paper presents a framework for accurate water supply network leakage location based on Residual Network (ResNet). This study proposes a leak localization idea with a parallel classification and regression process that enables the framework to pinpoint the exact position of leak points in the pipeline. Furthermore, a multi-supervision mechanism is designed in the regression process to speed up the model’s convergence. For a pipe network containing 40 pipes, the positioning accuracy of the pipe section is 0.94, and the MSE of the specific location of the leakage point is 0.000435. For the pipe network containing 117 pipes, the positioning accuracy of the pipe section is 0.91. The MSE of the specific location of the leakage point is 0.0009177. Experiments confirm the robustness and applicability of the framework.

     

城乡统筹背景下的城市供水规划方法研究——平谷新城供水专项规划

由于历史问题导致农村供水中存在水质较差,水量和水压得不到保障等问题,在目前新农村建设的背景下,需要以城乡统筹的观念重新审视农村供水系统,并探索其与城市供水系统之间的关系及整合优化方法。在此背景下,探讨了城乡统筹情况下的城市供水规划的方法流程,以确保城市供水系统最大发挥效力保障周边村镇的供水安全,具体规划流程为：分析区域水资源条件、分析供水现状及存在问题、进行供水需水量预测及供需平衡分析、编制水厂及管网规划,最后,以北京市平谷新城为例进行具体的案例分析。     

考虑全寿命周期成本的供水管网优化设计

针对城市管网的传统优化设计中仅考虑初始投资而没有考虑运行过程中维修管理成本的问题,提出了基于全寿命周期成本(LCC)的管网优化模型和计算方法。通过对管网建造成本及运行阶段维修管理成本的定量分析,建立了以全寿命周期总费用最低为目标的优化模型,并利用PSO算法对管径进行优化设计。通过实例分析,分别得到两种常用管材的最优管径,并基于寿命周期成本对比分析为管网设计阶段的方案选择和优化设计提供了依据。     

Identifying Pipes and Valves of High Importance for Efficient Operation and Maintenance of Water Distribution Systems

Failure of a pipe or valve in a water distribution system causes service disruption and other inconveniences to the customers at or downstream of the failure location. To minimize the impact of such a pipe or valve failure, it is crucial to identify those pipes or valves whose failure will have the most severe consequences in degrading the performance of the system relative to that of other pipes or valves. In this paper, we develop two failure analysis methodologies, Pipe-by-Pipe and Valve-by-Valve, to prioritize the importance of pipes and valves in a water distribution system. The relative importance of individual pipes and valves is evaluated according to the number of customers who are forced out of service as a consequence of a pipe or valve failure. The methodologies are based on a segment-finding algorithm which defines a series of isolated pipes in the case of pipe or valve failure. A procedure based on the Breadth First Search is also developed to find sections of pipes that are unintentionally isolated in the isolation procedure for failed pipes. The number of unintentionally isolated customers is included in the Pipe-by-Pipe and Valve-by-Valve analyses in order to incorporate this negative effect of unintended isolation of pipes. The methodologies are applied to a case study of a water distribution system for which the most important pipe and valve are identified. The results are analyzed to form a guideline for improving the system reliability. The proposed methodologies were found to be a valuable tool for ensuring efficient operation and developing appropriate maintenance strategies, and thereby for improving the reliability of many water distribution systems.     

Parameter Estimation in Water Distribution Networks

Estimation of pipe roughness coefficients is an important task to be carried out before any water distribution network model is used for online applications such as monitoring and control. In this study, a combined state and parameter estimation model for water distribution networks is presented. Typically, estimation of roughness coefficient for each individual pipe is not possible due to non-availability of sufficient number of measurements. In order to address this problem, a formal procedure based on K-means clustering algorithm is proposed for grouping the pipes which are likely to have the same roughness characteristics. Also, graph-theoretic concepts are used to reduce the dimensionality of the problem and thereby achieve significant computational efficiency. The performance of the proposed model is demonstrated on a realistic urban water distribution network.     

Water Supply System Performance for Different Pipe Materials Part II: Sensitivity Analysis to Pressure Variation

In water supply systems there are many situations during normal operation that induce the occurrence of pressure transients, where high pressures are followed by low, sometimes even negative pressures. These transients may cause ruptures in pipes creating thus leaks or opportunities for contaminants to enter the water supply system. Thus severe pressures transients should be avoided or adequately controlled in potable drinking systems. The level of service provided by water distribution systems is an important matter in the water industry of today. However, the measure of the performance of a pipe system network is not a straightforward task. In this study the performance of pressures in two networks (a cast iron network and a polyethylene network) with the same typology was compared. The transient state conditions were induced by different typical hydromechanical devices operation characterised by a sudden pumps trip-off, a leakage occurrence and a closure of an automatic control valve. For the hydraulic simulations, advanced models based on numerical computation for steady and transient state conditions were used. A performance evaluation model was developed to analyse each type of situation since the simulation time period and the concerns regarding the system behaviour can be fairly different.     

Reliability Assessment of Urban Water Distribution Networks Under Seismic Loads

Presented herein is a methodology for the seismic assessment of the reliability of urban water distribution networks (UWDN) based on general seismic assessment standards, as per the American Lifelines Alliance (ALA) guidelines, and localized historical records of critical risk-of-failure metrics pertaining to the specific UWDN under assessment. The proposed methodology is applicable to UWDN under both normal or abnormal operating conditions (such as intermittent water supply), and the assessment of reliability incorporates data of past non-seismic damage, the vulnerabilities of the network components against seismic loading, and the topology of a UWDN. Historical data obtained using records of pipe burst incidents are processed to produce clustered ‘survival curves’, depicting the pipes’ estimated survival rate over time. The survival curves are then used to localize the generalized fragility values of the network components (primarily pipes), as assessed using the approach suggested by the ALA guidelines. The network reliability is subsequently assessed using Graph Theory (Djikstra’s shortest path algorithm), while the system reliability is calculated using Monte Carlo simulation. The methodology proposed is demonstrated on a simple small-scale network and on a real-scale district metered area (DMA). The proposed approach allows the estimation of the probability that a network fails to provide the desired level of service and allows for the prioritization of retrofit interventions and of capacity-upgrade actions pertaining to existing water pipe networks.     

Multi-Level Decision-Making for Inter-Regional Water Resources Management with Water Footprint Analysis and Shared Socioeconomic Pathways

This study develops a synergistic optimization framework for planning inter-regional water resources management system under shared socioeconomic pathways; this framework integrates multi-level and robust flexible programs. The upper-level model determines minimum social loss induced by water exploitation, the middle-level one focuses exclusively on pollutant emissions, and the lower-level one aims to achieve maximum economic benefits. An improved multi-level interactive algorithm is proposed to balance the satisfaction degree of constraints and goals to achieve optimal. The effectiveness of the developed multi-level model is illustrated through a real-world case in Wuhan City Circle. Results indicate that the overall water resources performance in Wuhan City Circle is satisfactory, especially in Xianning and Huanggang, whereas some water footprint deficits exist in Wuhan, Xiaogan, and Tianmen. Climate scenarios have a remarkable effect on social loss but only slightly affect water supply strategies, pollutant emissions, and economic benefits. A high satisfactory degree results in a low risk of insufficient water supply and excessive pollutant emissions. Thus, satisfactory degree can be used as an evaluation indicator for identifying the amount of credible and reliable risk on final decisions. The findings of this study can enable stakeholders to grasp the inherent conflicts and trade-offs between environmental and economic interests.

     

河南省典型枯水年水资源脆弱性评价及贡献因子识别

水资源脆弱性评价是水安全的重要度量方式,水资源安全是区域可持续发展的基础。以河南省18个市区为研究单元,从自然条件、社会经济、供用耗水等3个子系统选取指标建立评价体系,运用熵权法、线性加权法求解其典型枯水年水资源脆弱性,从城市、区域、全省角度分析水资源子系统指数、脆弱性指数,并采用贡献度模型识别了水资源脆弱性主要贡献因子,以期为河南省水资源管理提供科学依据。结果表明:（1）整体上看,3个子系统水资源脆弱性指数大小排序为自然条件>供用耗水>社会经济;城市和区域的水资源子系统指数、脆弱性指数存在一定的差异,且有自西南向东北逐渐增大的趋势;全省水资源为Ⅲ级中等脆弱性。（2）18个市区及全省水资源脆弱性3个子系统贡献度排序为自然条件>供用耗水>社会经济;水资源脆弱性的主要贡献因子集中在自然条件子系统的4个指标。此外,社会经济子系统中的亩均化肥折纯量和供用耗水子系统中的人均综合用水量、亩均灌溉用水量也是主要贡献因子。最后,提出“多渠道供水,提高供水侧能力”“合理扩张城镇、优化人口经济结构,提高城市水平”“提高用水效率,节约用水”的差异化“降脆”策略,以实现水资源可持续发展。     

城市水安全指数及其评价标准

考虑现有水安全定义以及水安全系统的特征,在尝试给出城市水安全定义的基础上,从城市规模、防洪安全、供水安全以及水环境安全4个方面,构建了针对南方湿润地区的城市水安全评价指标体系以及评价标准,并选用层次分析法确定了各指标的权重。借鉴边际效益递减原理,利用指数型功效函数实现了指标的标准化。引入协调度和发展度的概念,用于衡量水安全系统及其子系统发展的有序性、稳定行和协调性。利用该模型对武汉市2003年-2009年水安全状况进行了评价,计算结果表明,水安全目前处于"相对安全"状态,并且有逐年改善的趋势。实例应用结果验证了该模型的可行性与有效性,在城市水安全评价中有一定应用价值。     

供水工程给水管道的选择

目前,应用于给水领域的管道从材料上分为金属和非金属两大类.近年来,为发挥各种材料的优势,给水用复合管道发展很快,如塑料与塑料复合,塑料与金属复合等.选择给水用管道的原则是:物理机械性能良好,强度高,保证连续、安全、可靠供水;管材及所有配套产品,都要保证卫生性能符合标准要求.     

南宁市城市应急供水系统建设探讨

为应对突发性水源污染事件,建立南宁市应急供水系统,对南宁市城市饮用水源状况、城市供水现状及城市需水量进行了分析,从应急水源选择、应急技术设施建设与水厂改造、城市供水管网建设与维护等方面,对南宁市城市应急供水系统建设进行了探讨。     

Vulnerability to Drought of a Complex Water Supply System. The Upper Tiber Basin Case Study (Central Italy)

The importance of simulation models to assess the impacts of droughts and the effects of mitigation options on water supply systems is well known. However a common procedure about the exploitation of model results is not established yet. Vulnerability is used to characterize the performance of the system, and it can be a helpful indicator in the evaluation of the most likely failures. In this paper a water allocation model is applied to the water supply system of the upper Tiber Basin (Central Italy) in which both surface waters (rivers, reservoirs) and ground waters (wells, springs) are exploited to feed mainly irrigation and civil users. Drought vulnerability indices are calculated to analyze the performance of the supply system under different climate and management conditions. Water shortage scenarios are simulated as a progressive reduction of mean precipitation, an increase in its standard deviation or a combination of both. The model shows that the safety of the water supply system mainly relies on the reservoirs and that the foreseen increased exploitation of the springs to replace contaminated wells, could be seriously limited by discharge decrease during fall. The vulnerability reduction obtained by a hypothetical augmentation of the storage capacity through additional small reservoirs was positively tested by the model. In conclusion vulnerability indices and synoptic risk maps demonstrated to be useful tools to analyze the model outputs. They provide easy-to-read scenarios to be used in a decision making framework considering negotiating among the main users.     

Regional Water Use Structure Optimization Under Multiple Uncertainties Based on Water Resources Vulnerability Analysis

In this paper, a modeling framework by combining system dynamic (SD) model and optimal allocation model was developed to study water resources vulnerability and optimal water use structure, and the framework was applied in the middle reaches of Heihe River basin, northwest of China. The SD model could describe the dynamical change of water resources vulnerability by integrating water resources with socio-economic effect. The sensitivity analysis of SD model was then conducted to design appropriate scenarios for finding out the optimal development pattern, and based on which, an integrated water-saving scenario with lower water resources vulnerability was identified for optimization modeling. Then, an inexact fuzzy-parameter two-stage programming (IFTSP) model was developed and applied to optimize water use structure among industries under uncertainties. This study addresses the water resources vulnerability analysis in considering both water resources system and socio-economic system. Water resources vulnerability analysis was combined with optimization model to make adaptive water resources management plans. And the optimal allocation schemes under lower water resources vulnerability are more advantageous for regional sustainable development.     

Application of the Shuffled Frog Leaping Algorithm for the Optimization of a General Large-Scale Water Supply System

A water supply system is a complex network of pipes, canals and storage and treatment facilities that collects, treats, stores, and distributes water to consumers. Increasing population and its associated demands requires systems to be expanded and adapted over time to provide a sustainable water supply. Comprehensive design tools are needed to assist managers determine how to plan for future growth. In this study, a general large-scale water supply system model was developed to minimize the total system cost by integrating a mathematical supply system representation and applying an improved shuffled frog leaping algorithm optimization scheme (SFLA). The developed model was applied to two hypothetical water communities. The operational strategies and the capacities for the system components including water transport and treatment facilities are model decision variables. An explicit representation of energy consumption cost for the transporting water in the model assists in determining the efficacy of satellite wastewater treatment facilities. Although the water supply systems studied contained highly nonlinear terms in the formulation as well as several hundred decisions variables, the stochastic search algorithm, SFLA, successfully found solutions that satisfied all the constraints for the studied networks.     

A Graph-Theoretic Framework for Assessing the Resilience of Sectorised Water Distribution Networks

Water utilities face a challenge in maintaining a good quality of service under a wide range of operational management and failure conditions. Tools for assessing the resilience of water distribution networks are therefore essential for both operational and maintenance optimization. In this paper, a novel graph-theoretic approach for the assessment of resilience for large scale water distribution networks is presented. This is of great importance for the management of large scale water distribution systems, most models containing up to hundreds of thousands of pipes and nodes. The proposed framework is mainly based on quantifying the redundancy and capacity of all possible routes from demand nodes to their supply sources. This approach works well with large network sizes since it does not rely on precise hydraulic simulations, which require complex calibration processes and computation, while remaining meaningful from a physical and a topological point of view. The proposal is also tailored for the analysis of sectorised networks through a novel multiscale method for analysing connectivity, which is successfully tested in operational utility network models made of more than 100,000 nodes and 110,000 pipes.     

大亚湾引水工程管材的选用

根据大亚湾引水工程管线的布置位置、供水压力、土壤性质及其施工维护等条件经比较选择了PCP管作为主要输水管材,并配合球墨铸铁管和钢管解决穿公路和过河的问题。对引水工程中的隧洞、加压泵站、水锤设防诸技术问题作了简介;对不同土质的地基处理作了较详细地阐述。     

Water Network Protection from Intentional Contamination by Sectorization

Each single phase of a water supply network, from water adduction to distribution to end-users, is exposed to many diverse potential sources of intentional contamination (or malicious attacks). One of the most dangerous threats is a backflow attack that occurs when a pump system, easily available on the market, is utilized to overcome the pressure gradient of network pipes. In this work, a simple backflow attack with cyanide being introduced into a real-water system is modeled and the most dangerous introduction points for a contaminant incident are defined. Moreover, the network vulnerability has been analyzed by computing the lethal dose of cyanide ingested by users and the total length of the contaminated water system. Eventually the effects of network partitioning and district isolation to protect water supply systems have been investigated. The results show how district closing - by network sectorization techniques used to improve leakage search and reduction - can significantly decrease contaminant diffusion and protect part of the users from cyanide uptake. Network sectorization can also reduce the risk of simple malicious attacks because several introduction points are necessary to have a massive negative impact on the network. Simulation results also show that in some cases water network partitioning may worsen water network protection and further studies are necessary to design water districts for network security and safety.     

PCCP管在河南省南水北调中线配套工程中的运用

随着我国对水资源的调整和分配,长距离引调水工程逐年增多。我国引进了大量的新型管材和新的生产工艺,为供水工程管材的选择提供了更多的余地。PCCP是近几年在供水工程中采用较多的新兴管材,本文以PCCP管材在河南省南水北调中线配套工程中的应用为例,从PCCP管材的结构组成、受力特性、设计成果以及施工安装技术要求等方面详细介绍其特点,为同类工程应用该种管材提供参考。     

Evolving Effective Hydraulic Model for Municipal Water Systems

Constructing a robust hydraulic network model is vitally important, but a time-consuming task. Over last two decades, several approaches using optimization techniques have been developed for identifying model parameters. Although most of the methods can make the model agree with field observations, few are able to achieve a good level of accuracy in terms of determining the correct model parameters for a water distribution system. The previously developed methods appear to be lacking versatility for users to specify calibration tasks given real data for a real system. This paper proposes a comprehensive framework for evolving a hydraulic network model. Calibration tasks can be specified according to data availability and model application requirements. It allows an engineer to (1) flexibly choose any combination of the model parameters such as pipe roughness, junction demand and link (pipes, valves and pumps) operational status; (2) easily aggregate model parameters to reduce the problem dimension for expeditious calculation and (3) consistently specify boundary conditions and junction demand loadings that are corresponding to field data collection. A model calibration is then defined as an implicit nonlinear optimization problem, which is solved by employing a competent evolutionary algorithm. With this methodology, a modeler can be fully assisted to carry out not only a single parameter optimization run, but also a variety of calibration tasks in a progressive manner according to practical system conditions, thus it is possible to achieve a good model calibration with high level of confidence. The method has been applied to the model of a municipal water system to demonstrate the efficacy and robustness of the evolutionary modeling practices.