Iterative Methods for Looped Network Pipeline Calculation

Since the value of the hydraulic resistance depends on flow rate, problem of flow distribution per pipes in a gas or water distributive looped pipelines has to be solved using iterative procedure. A number of iterative methods for determining of hydraulic solution of pipeline networks, such as, Hardy Cross, Modified Hardy Cross, Node-Loop method, Modified Node method and M.M. Andrijašev method are shown in this paper. Convergence properties are compared and discussed using a simple network with three loops. In a municipal gas pipeline, natural gas can be treated as incompressible fluid. Even under this circumstance, calculation of water pipelines cannot be literary copied and applied for calculation of gas pipelines. Some diferences in calculations of networks for distribution of these two fluids, i.e. water apropos natural gas are also noted.     

An Automated Tool for Smart Water Network Partitioning

Water Network Partitioning (WNP) represents the application of the “divide and conquer” paradigm to a Smart WAter Network (SWAN) that allows the improved application of techniques for water balance and pressure control. Indeed, these techniques can be applied with greater effectiveness by defining smaller permanent network parts, called District Meter Areas (DMAs), created by the insertion of gate valves and flow meters. The traditional criteria for the design of network DMAs are based on empirical suggestions (number of properties, length of pipes, etc.) and on approaches such as ‘trial and error’, even if used together with hydraulic simulation software. Nevertheless, these indications and procedures are very difficult to apply to large water supply systems because the insertion of gate valves modifies the original network layout and may considerably worsen the hydraulic performance of the water network. The proposed tool, based on some graph partitioning techniques, commonly applied in distributed computing, and on an original optimisation technique, allows the automatic design of a WNP comparing different possible layouts that are compliant with hydraulic performance. In this paper, the methodology was tested on a real case study using some performance indices to compare different WNPs. The proposed tool was developed in Phyton and integrates graph partitioning, hydraulic simulation techniques and a heuristic optimisation criterion. It allows the definition of DMAs with resulting performance indices that are very similar to the original network layout.     

水资源空间均衡理论方法及应用研究框架

面对日益凸显的水资源空间不均衡问题和矛盾,推进和落实水资源空间均衡已成为当前水利工作的一项重要内容。但是到底什么是水资源空间均衡以及其理论方法是什么,是当前迫切需要回答的问题。通过对现有空间均衡研究的梳理和分析,结合水资源空间均衡发展理念的形成背景,提出了水资源空间均衡的定义以及水资源空间均衡理论的概念;在对水资源空间均衡原理理解的基础上,提出了水资源空间均衡理论体系框架,并对其主要研究内容进行了介绍;最后,从理论、方法和应用3个方面对水资源空间均衡研究的下一步工作进行了展望。总体来看,水资源空间均衡理论方法的研究对解决我国现代治水实践中的空间不均衡问题,支撑国家现代化水利建设论证与规划,促进水资源、经济社会和生态环境空间均衡发展具有重要的指导作用,可为今后开展水资源空间均衡管控与实践奠定基础。     

用聚类算法及Hopfield神经网络布置环状管网

为了降低供水管网的工程投资,提出了一种环状给水管网优化设计的方法,把环状管网布置问题用K-Means算法分解成许多小规模的环状问题,对于每一个小规模的环状管网用Hopfiled连续型神经网络求解环状的最短距离,然后把各个基环当成一个点,再用Hopfield神经网络以较大的概率求出最优路径。对某小区58个供水点进行了供水管网实例计算,结果表明:该供水管网的质心间最短距离为2.893 7 km,能量函数为递减状态且最终的能量函数值为1.447,再连接相邻聚类中的最接近的两个点就形成供水管网的环状布置。     

Framework for Hyperparameter Impact Analysis and Selection for Water Resources Feedforward Neural Network

Water Resources Management - The Feedforward Neural Network (FNN) is currently commonly used in problems involving water resources. However, the hyperparameters have received minimal attention: (i)...     

A Framework for Ground Water Management Based on Bayesian Network and MCDM Techniques

Groundwater resources are steadily subjected to increasing water demands. The aquifers are considered as the most accessible source of fresh water. In recent years, they have been faced with severe water withdrawal in arid and semi-arid countries like Iran and thus some aquifers was considered as forbidden aquifers that it means the water withdrawal from these aquifers is unauthorized. Given a critical situation, groundwater resources management in the form of tools such as monitoring the level of the aquifers and developing the restoring scenarios is essential. Therefore, for this purpose, a framework has been developed based on prediction of groundwater level using Bayesian Networks (BNs) model. Furthermore, Multi Criteria Decision Making methods (MCDM) techniques proposed and employed for ranking of proposed groundwater management scenarios. This framework was evaluated for restoring the Birjand aquifer in Iran in different hydrological conditions. A probabilistic Dynamic BN was proposed for groundwater level prediction under uncertainties. After analyzing the obtained results, the applicable short term scenarios for groundwater management as well as appropriate economic, social and technical criteria were defined for decision making procedure. Then, using elicitation of decision makers’ opinions on the relative importance and performance of criteria, SAW, TOPSIS and PROMETHEE-II techniques were applied to rank the scenarios and the obtained results were aggregated by Borda method for final ranking of the scenarios. Lastly, the final results demonstrates the capability of the proposed framework for groundwater resources planning and management which can be employed for reducing the risk of aquifer level declining.     

Tariff Suitability Framework for Water Supply Services

Water supply (WS) tariffs have evolved significantly in the past decades, although in a varying fashion around the world. Indeed, this development is linked to increasingly demanding requirements, or objectives that have to be achieved by water utilities (e.g., stricter quality standards and infrastructure maintenance levels, cost recovery, social concerns and environmental protection demands). The perception of WS tariffs as a powerful management tool, subject to context dependent objectives, raises the concern on how utilities prioritize them. This hierarchy is desirable due to the possible conflicting nature of objectives. From that point of view, and on the basis of protecting the public interest, the fitness between objectives set by the utilities and actual needs may require a broader institutional approach. The need for regulatory activity may be required in the context of too much arbitrariness in tariff setting procedures. For this objective, a regulatory tool is set, based on multicriteria decision analysis (MCDA) modeling methods, to provide a requisite framework capable of considering the multiple dimensions of WS tariffs and the assessment of specialists, practitioners and other legitimate stakeholders in the ‘tariff setting’ decision making process. The specified tariff suitability framework (TSF) will work as a regulatory tool, taking into account the utilities’ particular context and background factors. The outcomes allow to determine the tariff suitability and to build tailored policy recommendations, which are critical aspects for a sound regulation.     

A Framework for Short-term Operational Planning for Water Grids

Water grids are emerging as a response to water scarcity in many urban areas. These grids are comprised not only of traditional surface and groundwater supplies, but also alternative, climate-independent water sources such as desalination and wastewater recycling, as well as one and two-way pipelines connecting surface-water supplies in different regions. The complexity and heterogeneity of these water supply networks brings new challenges to water management. Water managers need to determine strategies to operate the system in terms of multiple objectives, subject to uncertainty and boundary conditions relating to climate, demand and infrastructure. This paper outlines a framework of methodologies for developing optimal operating plans for short-term planning for water grids, in terms of the objectives of interest.     

Application of Several Meta-Heuristic Techniques to the Optimization of Real Looped Water Distribution Networks

The optimization of looped water distribution systems is a complex problem as the pipe flows are unknown variables. Although many researchers have reported algorithms for minimizing the network cost applying a large variety of techniques, such as linear programming, non-linear programming, global optimization methods and meta-heuristic approaches, a totally satisfactory and efficient method is not available as yet. Many works have assessed the performance of these techniques using small or medium-sized benchmark networks proposed in the literature, but few of them have tested these methods with large-scale real networks. The aim of this paper is to evaluate the performance of several meta-heuristic techniques: genetic algorithms, simulated annealing, tabu search, and iterated local search. These techniques were first validated and compared by applying them to a medium-sized benchmark network previously reported in the literature. They were then applied to a large irrigation water distribution network that has been proposed in a previous work to assess their performance in a practical application. All the methods tested performed adequately well, compared with the results found in previous works. Genetic algorithm was more efficient when dealing with a medium-sized network, but other methods outperformed it when dealing with a real complex one.     

A Sustainable Decision Support Framework for Urban Water Management

This paper develops a decision support framework that assists managers in the urban water industry to analyse a mix of water service options, at the whole-of-city scale. The decision support framework moves decision-making in urban water systems from traditional command and control approaches that tend to focus on an outcome at a point in time to a more sustainable, inclusive and dynamic decision-making process driven by social learning and engagement. While available models and evaluation techniques provide valuable input to decision-making, the complex nature of urban water systems requires more than just social and economic criteria to be considered as part of decision support frameworks. The authors believe that current decision support frameworks need to be presented in a way that incorporates adaptive management and integrated urban water management strengths at the strategic and operational level. The inclusion of social learning and engagement is necessary to achieving this end.     

Development of a Framework for Water Quality Monitoring in Mexico

ABSTRACT

An attempt is being made in Mexico to develop a water quality monitoring framework that is cost-effective, reliable, accessible, and one that would actually be extensively used by the potential users. The article analyzes the experiences from other developing countries, where the overall usability of the system leaves much to be desired, outlines the essential requirements of a functional monitoring system, critical monitoring issues that should be considered, and the process recommended for developing efficient water quality monitoring in Mexico.     

区域水资源可持续利用预警评价的理论框架探讨

为建立系统性和可操作性的区域水资源可持续利用预警评价的理论框架,从方法论的角度,阐述了区域水资源系统、区域水资源可持续利用和区域水资源可持续利用预警评价的基本概念,论述了区域水资源可持续利用系统的预警原理和调控原理,提出了区域水资源可持续利用预警评价方法论,上述理论框架在区域水安全管理中具有一定的参考应用价值。     

A Framework for an Agent-Based Model to Manage Water Resources Conflicts

Competition for use of water is increasing and leads to many conflicts among competing interests with complex goals and water management systems. Technical system models are essential to create performance and other decision information, but models to simulate views of the competing parties are also needed to help resolve or mitigate conflicts. Agent-based models (ABMs) offer promise to fill this role, and in this study a new approach to agent-based modeling is introduced to simulate the behavior and interactions of the parties participating in a conflict scenario, which is modeled as a game. To develop this framework, we considered water issues of California’s Sacramento-San Joaquin Delta region as an example of a long-standing situation, with emphasis on the San Joaquin watershed. However, this approach can be used in other watersheds and more complex systems. The ABM explains the interactions among the parties and how they can be encouraged to cooperate in the game to work toward a solution. The model also enables decision-makers to test management scenarios and understand the consequences of their decisions on different stakeholders and their behaviors.     

A Neurofuzzy Decision Framework for the Management of Water Distribution Networks

Among the most important components of sustainable management strategies for water distribution networks is the ability to integrate risk analysis and asset management decision-support systems (DSS), as well as the ability to incorporate in the analysis financial and socio-political parameters that are associated with the networks in study. Presented herein is a neurofuzzy decision-support system for the performance of multi-factored risk-of-failure analysis and pipe asset management, as applied to urban water distribution networks. The study is based on two datasets (one from New York City and the other from the city of Limassol, Cyprus), analytical and numerical methods, and artificial intelligence techniques (artificial neural networks and fuzzy logic) that capture the underlying knowledge and transform the patterns of the network’s behaviour into a knowledge-repository and a DSS.     

Assessing Decentralised Water Solutions: Towards a Framework for Adaptive Learning

This paper reports on the use of qualitative analysis to inform a risk analysis framework for decentralised water systems. To realise the benefits from these technologies, a methodology is applied to learn from previous difficulties in implementing and managing them. A workshop process was used to capture stories from industry professionals on difficulties they have encountered in planning and implementation. Qualitative analysis of story narratives revealed stages where there was some type of development process failure; as well as failure modes and factors influencing the difficulties encountered. The analysis also generated insights: difficulties in one part of the development process tends to propagate to subsequent stages; system difficulties most often occurred in the policy stage of development due to institutional inertia and lack of adaptive governance; and the best indicator of problems with a decentralised system was complaints of poor water quality. Furthermore, this paper also provides a method to learn from past difficulties by identifying what data needs to be collected in order to populate a risk model which can be used for improving risk assessment of the development process for decentralised systems. This can provide a basis for better decision making, policy and guidelines; an important factor in mainstream acceptance.     

城市水安全及其研究框架

根据水资源的利、害二元特性,以城市水循环为基础,分析影响水安全因素的发生环节与成因,在可持续发展和系统论的指导下,提出城市水安全的研究内容应包括城市水安全理论、应用技术和管理体系三个层次的内容。最终目的是实现水安全的可持续发展。     

欧盟水框架指令初议

欧盟水框架指令（WFD）是近几十年来欧盟在水资源领域颁布的最重要指令。简要分析了欧盟水框架指令产生的背景及过程,概述了指令主要内容及法律效力,分析了其在流域管理、规划、价格激励、信息咨询等方面的主要特点,并结合现代水资源管理的特点,提出几点建议。     

斐济南德瑞瓦图水电站配水环管保温保压浇筑

在高水头机组中蜗壳和配水环管保压浇筑混凝土施工技术目前已广泛应用,但同时采取保温浇筑的却很少。文章介绍了斐济项目配水环管保温保压浇筑混凝土的方案及施工过程数据,经论证,保温保压浇筑有利于水电站的长期安全可靠运行。     

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.