The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Avi Ostfeld - One of the best experts on this subject based on the ideXlab platform.
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Challenges in Drinking Water Distribution Systems Security Modeling
2020Co-Authors: Avi OstfeldAbstract:This paper is on challenges in drinking Water Distribution Systems security modeling connected to OCMS, addressing research and practical issues coming-out from two recent activities which hold the state of the art on Water Distribution Systems security modeling: (1) the Journal of Water Resources Planning and Management Division, ASCE, Vol. 132, No. 4, Special Issue on Drinking Water Distribution Systems Security, and (2) the Battle of the Water Sensor Networks (BWSN): A Design Challenge for Engineers and Algorithms, held at the 8th Annual Water Distribution System Analysis Symposium Cincinnati, Ohio, USA(Ostfeld et al., 2006).
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Water Age Clustering for Water Distribution Systems
Procedia Engineering, 2020Co-Authors: Elad Salomons, Avi OstfeldAbstract:Abstract This work presents an algorithm for Water Distribution Systems Water age clustering. The objective is to cluster a Distribution system into Water age sub-zones whose Water age variability is minimized within each cluster. The algorithm stages are: (1) Water age computation for each system node, (2) kick-off at a number of clusters equal to the number of nodes (i.e., each node initially acts as a cluster), (3) search for the two connected (by link) clusters which have the smallest absolute Water age difference, and combine them into a single cluster; characterize their Water age value as the weighted arithmetic mean of the two clusters, and (4) repeat step 3 until all nodes are lumped into a single cluster (i.e., the entire Water Distribution system). The algorithm thus spans all possible clusters starting from the total number of system nodes and up to a one cluster which holds the entire system layout. The model, through a clustering numbering trade-off, is demonstrated on a mid-size Water Distribution system.
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Active Contamination Detection in Water-Distribution Systems
Journal of Water Resources Planning and Management, 2020Co-Authors: Stelios G. Vrachimis, Ron Lifshitz, Demetrios G. Eliades, Marios M. Polycarpou, Avi OstfeldAbstract:AbstractIn this paper, we propose a novel methodology for altering the area monitored by Water quality sensors in Water Distribution Systems (WDS) when there is suspicion of a contamination event. ...
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Clustering for Analysis of Water Distribution Systems
Journal of Water Resources Planning and Management, 2018Co-Authors: Ron Lifshitz, Avi OstfeldAbstract:AbstractSimplification methodologies for complex Water Distribution Systems (WDS) are essential for better understanding Water Distribution system behavior. Such methodologies have substantially im...
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characterizing cyber physical attacks on Water Distribution Systems
Journal of Water Resources Planning and Management, 2017Co-Authors: Riccardo Taormina, Stefano Galelli, Nils Ole Tippenhauer, Elad Salomons, Avi OstfeldAbstract:AbstractThis work contributes a modeling framework to characterize the effect of cyber-physical attacks (CPAs) on the hydraulic behavior of Water Distribution Systems. The framework consists of an ...
Lina Perelman - One of the best experts on this subject based on the ideXlab platform.
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automated sub zoning of Water Distribution Systems
Environmental Modelling and Software, 2015Co-Authors: Lina Perelman, Ami Preis, Michael Allen, Mudasser Iqbal, Andrew J WhittleAbstract:Water Distribution Systems (WDS) are complex pipe networks with looped and branching topologies that often comprise thousands to tens of thousands of links and nodes. This work presents a generic framework for improved analysis and management of WDS by partitioning the system into smaller (almost) independent sub-Systems with balanced loads and minimal number of interconnections. This paper compares the performance of three classes of unsupervised learning algorithms from graph theory for practical sub-zoning of WDS: (1) Global clustering - a bottom-up algorithm for clustering n objects with respect to a similarity function, (2) Community structure - a bottom-up algorithm based on the property of network modularity, which is a measure of the quality of network partition to clusters versus randomly generated graph with respect to the same nodal degree, and (3) Graph partitioning - a flat partitioning algorithm for dividing a network with n nodes into k clusters, such that the total weight of edges crossing between clusters is minimized and the loads of all the clusters are balanced. The algorithms are adapted to WDS to provide a practical decision support tool for Water utilities. Visual qualitative and quantitative measures are proposed to evaluate models' performance. The three methods are applied for two large-scale Water Distribution Systems serving heavily populated areas in Singapore. Display Omitted We apply three classes of unsupervised learning algorithms for WDS partition.Visual and quantitative metrics are used for performance evaluation and comparison.We provide a practical decision support tool for Water utilities.Results show superiority of the community structure and graph partitioning methods.
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Water Distribution Systems event detection
2012 Complexity in Engineering (COMPENG). Proceedings, 2012Co-Authors: Lina Perelman, Avi Ostfeld, Jonathan Arad, Nurit Oliker, Mashor HoushAbstract:Since the events of 9/11 2001 in the US the world public awareness to possible terrorist attacks on Water supply Systems has increased dramatically, causing the security of drinking Water Distribution Systems to become a major concern around the globe. Among the different threats, a deliberate chemical or biological contaminant injection is the most difficult to address, both as a consequence of the uncertainty surrounding the type of the injected contaminant and its consequences, as well as the uncertainty of location and time of the injection. In principle, a pollutant can be injected at any Water Distribution system connection (node) using a pump or a mobile pressurized tank. Although backflow preventers provide an obstacle to such actions, they do not exist at all connections, and at some might not be functional. This paper describes recent effort modeling of Avi Ostfeld's research team on Water Distribution Systems event detection. The basic event detection framework is entitled AEDA (Aquatic Event Detection Algorithm) which utilizes Artificial Neural Networks (ANNs) for studying the interactions between multivariate Water quality parameters and detecting possible outliers. Other layers on top of AEDA explore tradeoffs among contamination event parameters and improving its performance capabilities. Those and AEDA are reviewed in this paper.
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COMPENG - Water Distribution Systems event detection
2012 Complexity in Engineering (COMPENG). Proceedings, 2012Co-Authors: Lina Perelman, Avi Ostfeld, Jonathan Arad, Nurit Oliker, Mashor HoushAbstract:Since the events of 9/11 2001 in the US the world public awareness to possible terrorist attacks on Water supply Systems has increased dramatically, causing the security of drinking Water Distribution Systems to become a major concern around the globe. Among the different threats, a deliberate chemical or biological contaminant injection is the most difficult to address, both as a consequence of the uncertainty surrounding the type of the injected contaminant and its consequences, as well as the uncertainty of location and time of the injection. In principle, a pollutant can be injected at any Water Distribution system connection (node) using a pump or a mobile pressurized tank. Although backflow preventers provide an obstacle to such actions, they do not exist at all connections, and at some might not be functional. This paper describes recent effort modeling of Avi Ostfeld's research team on Water Distribution Systems event detection. The basic event detection framework is entitled AEDA (Aquatic Event Detection Algorithm) which utilizes Artificial Neural Networks (ANNs) for studying the interactions between multivariate Water quality parameters and detecting possible outliers. Other layers on top of AEDA explore tradeoffs among contamination event parameters and improving its performance capabilities. Those and AEDA are reviewed in this paper.
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Water Distribution Systems simplifications through clustering
Journal of Water Resources Planning and Management, 2012Co-Authors: Lina Perelman, Avi OstfeldAbstract:AbstractFor large Water-Distribution Systems fully detailed models result in a substantial amount of data, making it difficult to manage, monitor, and understand how the main structure of the system works. A possible way to cope with this difficulty is to gain insight to the system behavior by simplifying its operation through topological/connectivity analysis. The objective of this study is to develop and demonstrate a generic topological-based scheme to aid in the analysis of Water-Distribution Systems. The methodology relies on clustering, which divides the Distribution system into strongly and weakly connected sub-graphs using the depth first search (DFS) and breadth first search (BFS) graph algorithms. The partitioning results in a connectivity matrix that represents the interconnections between clusters, which can support, for example, a response modeling plan in case of a contamination intrusion incident. A detailed illustrative example and a real complex Water-Distribution system are explored for ...
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Short communication: Topological clustering for Water Distribution Systems analysis
Environmental Modelling and Software, 2011Co-Authors: Lina Perelman, Avi OstfeldAbstract:Municipal Water Distribution Systems may consist of thousands to tens of thousands of hydraulic components such as pipelines, valves, tanks, hydrants, and pumping units. With the capabilities of today's computers and database management software, ''all pipe'' hydraulic simulation models can be easily constructed. However, the uncertainty and complexity of Water Distribution Systems interrelationships makes it difficult to predict its performances under various conditions such as failure scenarios, detection of sources of contamination intrusions, sensor placement locations, etc. A possible way to cope with these difficulties is to gain insight in to the system behavior by simplifying its operation through topological/connectivity analysis. In this study a tool of this kind based on graph theory is developed and demonstrated. The algorithm divides the system into clusters according to the flow directions in pipes. The resulted clustering is generic and can be utilized for different purposes such as Water security enhancements by sensor placements at clusters, or efficient isolation of a contaminant intrusion. The methodology is demonstrated on a benchmark Water Distribution system from the research literature.
Dragan Savic - One of the best experts on this subject based on the ideXlab platform.
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lost in optimisation of Water Distribution Systems a literature review of system design
Water, 2018Co-Authors: Helena Malajetmarova, Nargiz Sultanova, Dragan SavicAbstract:Optimisation of Water Distribution system design is a well-established research field, which has been extremely productive since the end of the 1980s. Its primary focus is to minimise the cost of a proposed pipe network infrastructure. This paper reviews in a systematic manner articles published over the past three decades, which are relevant to the design of new Water Distribution Systems, and the strengthening, expansion and rehabilitation of existing Water Distribution Systems, inclusive of design timing, parameter uncertainty, Water quality, and operational considerations. It identifies trends and limits in the field, and provides future research directions. Exclusively, this review paper also contains comprehensive information from over one hundred and twenty publications in a tabular form, including optimisation model formulations, solution methodologies used, and other important details.
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lost in optimisation of Water Distribution Systems a literature review of system operation
Environmental Modelling and Software, 2017Co-Authors: Helena Malajetmarova, Nargiz Sultanova, Dragan SavicAbstract:Optimisation of the operation of Water Distribution Systems has been an active research field for almost half a century. It has focused mainly on optimal pump operation to minimise pumping costs and optimal Water quality management to ensure that standards at customer nodes are met. This paper provides a systematic review by bringing together over two hundred publications from the past three decades, which are relevant to operational optimisation of Water Distribution Systems, particularly optimal pump operation, valve control and system operation for Water quality purposes of both urban drinking and regional multiquality Water Distribution Systems. Uniquely, it also contains substantial and thorough information for over one hundred publications in a tabular form, which lists optimisation models inclusive of objectives, constraints, decision variables, solution methodologies used and other details. Research challenges in terms of simulation models, optimisation model formulation, selection of optimisation method and postprocessing needs have also been identified. A review of operational optimisation of Water Distribution Systems is provided.Future challenges were identified, despite the large body of existing literature.Universally agreed formulation of an operational optimisation problem is needed.Algorithm performance for a particular problem requires improved understanding.A method for selecting only one solution for a real system needs to be developed.
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an efficient algorithm for sensor placement in Water Distribution Systems
Eighth Annual Water Distribution Systems Analysis Symposium (WDSA), 2008Co-Authors: G Dorini, Philip Jonkergouw, Zoran Kapelan, F Di Pierro, Dragan SavicAbstract:The objective of this paper is to present an optimal sensor placement methodology to assist in the effective and efficient detection of accidental and/or intentional contaminant intrusion(s) in Water Distribution Systems. The work presented here is done in response to call for papers for the Battle of the Water Sensors Networks (BWSN), at the Water Distribution Systems Analysis Symposium (2006). The above problem is formulated and solved as a constrained multiobjective optimisation problem. The four objectives are: (1) minimisation of the expected time of detection, (2) minimisation of the expected population affected prior to detection, (3) minimisation of the expected demand of contaminated Water prior to detection and (4) maximisation of the detection likelihood. The constraint modelled is the pre-specified number of detection sensors used in the sampling design. Decision variables are the sensor network locations. The solution methodology proposed is based on the novel Noisy Cross-Entropy Sensor Locator (nCESL) algorithm. This algorithm is applied to the two competition networks under four base contamination scenarios (A, B, C and D) and two different numbers of sensors available (5 and 20). The results obtained demonstrate the effectiveness and efficiency of the sensor placement methodology proposed. Copyright ASCE 2006.
Ami Preis - One of the best experts on this subject based on the ideXlab platform.
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automated sub zoning of Water Distribution Systems
Environmental Modelling and Software, 2015Co-Authors: Lina Perelman, Ami Preis, Michael Allen, Mudasser Iqbal, Andrew J WhittleAbstract:Water Distribution Systems (WDS) are complex pipe networks with looped and branching topologies that often comprise thousands to tens of thousands of links and nodes. This work presents a generic framework for improved analysis and management of WDS by partitioning the system into smaller (almost) independent sub-Systems with balanced loads and minimal number of interconnections. This paper compares the performance of three classes of unsupervised learning algorithms from graph theory for practical sub-zoning of WDS: (1) Global clustering - a bottom-up algorithm for clustering n objects with respect to a similarity function, (2) Community structure - a bottom-up algorithm based on the property of network modularity, which is a measure of the quality of network partition to clusters versus randomly generated graph with respect to the same nodal degree, and (3) Graph partitioning - a flat partitioning algorithm for dividing a network with n nodes into k clusters, such that the total weight of edges crossing between clusters is minimized and the loads of all the clusters are balanced. The algorithms are adapted to WDS to provide a practical decision support tool for Water utilities. Visual qualitative and quantitative measures are proposed to evaluate models' performance. The three methods are applied for two large-scale Water Distribution Systems serving heavily populated areas in Singapore. Display Omitted We apply three classes of unsupervised learning algorithms for WDS partition.Visual and quantitative metrics are used for performance evaluation and comparison.We provide a practical decision support tool for Water utilities.Results show superiority of the community structure and graph partitioning methods.
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Multi-objective optimization for conjunctive placement of hydraulic and Water quality sensors in Water Distribution Systems
Water Science and Technology: Water Supply, 2011Co-Authors: Ami Preis, Andrew Whittle, Avi OstfeldAbstract:Near real-time continuous monitoring Systems have been proposed as a promising approach for enhancing drinking Water utilities detect and respond efficiently to threats on Water Distribution Systems. Water quality sensors are aimed at revealing contamination intrusions, while hydraulic pressure and flow sensors are utilized for estimating the hydraulic system state. To date optimization models for placing sensors in Water Distribution Systems are targeting separately Water quality and hydraulic sensor network goals. Deploying two independent sensor networks within one Distribution system is expensive to install and maintain. It might thus be beneficial to consider mutual sensor locations having dual hydraulic and Water quality monitoring capabilities (i.e. sensor nodes which collect both hydraulic and Water quality data at the same locations). In this study a multi-objective sensor network placement model for conjunctive monitoring of hydraulic and Water quality data is developed and demonstrated using the multi-objective non-dominated sorted genetic algorithm NSGA II methodology. Two Water Distribution Systems of increasing complexity are explored showing tradeoffs between hydraulic and Water quality sensor location objectives. The proposed method provides a new tool for sensor placements.
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Multiobjective contaminant sensor network design for Water Distribution Systems
JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT-ASCE, 2008Co-Authors: Ami Preis, Avi OstfeldAbstract:A contaminant intentional intrusion into a Water Distribution system is one of the most difficult threats to address. This is because of the uncertainty of the type of the injected contaminant and its consequences, and the uncertainty of the location and intrusion time. An online contaminant sensor network is the main constituent to enhance the security of a Water Distribution system against such a threat. In this study a multiobjective model for Water Distribution system optimal sensor placement using the nondominated sorted genetic algorithm II is developed and demonstrated using two Water Distribution Systems of increasing complexity. Tradeoffs between three objectives are explored: (1) sensor detection likelihood; (2) sensor detection redundancy; and (3) sensor expected detection time. Pareto fronts are plotted for pairs of conflicting objectives, and simultaneously for all three. A contamination event heuristic sampling methodology is developed for overcoming the problem of contamination event sampling.
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Multiobjective contaminant response modeling for Water Distribution Systems security
Journal of Hydroinformatics, 2008Co-Authors: Ami Preis, Avi OstfeldAbstract:Following the events of 9/11/2001 in the US, the world public awareness\nto possible terrorist attacks on Water supply Systems has increased\nsignificantly. The security of drinking Water Distribution Systems has\nbecome a foremost concern around the globe. Water Distribution Systems\nare spatially diverse and thus are inherently vulnerable to intentional\ncontamination intrusions. In this study, a multiobjective optimization\nevolutionary model for enhancing the response against deliberate\ncontamination intrusions into Water Distribution Systems is developed\nand demonstrated. Two conflicting objectives are explored: ( 1)\nminimization of the contaminant mass consumed following detection,\nversus ( 2) minimization of the number of operational activities\nrequired to contain and flush the contaminant out of the system (i.e.\nnumber of valves closure and hydrants opening). Such a model is aimed at\ndirecting quantitative response actions in opposition to the\nconservative approach of entire shutdown of the system until flushing\nand cleaning is completed. The developed model employs the\nmultiobjective Non-Dominated Sorted Genetic Algorithm-II (NSGA-II)\nscheme, and is demonstrated using two example applications.
Kalanithy Vairavamoorthy - One of the best experts on this subject based on the ideXlab platform.
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methods and tools for managing losses in Water Distribution Systems
Journal of Water Resources Planning and Management, 2013Co-Authors: Harrison E Mutikanga, Saroj K Sharma, Kalanithy VairavamoorthyAbstract:AbstractThe Water industry worldwide is facing challenges of Water and revenue losses. To reduce these losses and improve efficiency of Water Distribution Systems, tools and methods have been developed over the years. This paper reviews the current tools and methodologies applied to assess, monitor, and control losses in Water Distribution Systems. The aim is to identify the tools and methods that have been applied, knowledge gaps, and future research needs. The review findings indicate that a number of Water loss management tools and methods have been developed and applied. They vary from simple managerial tools such as performance indicators to highly sophisticated optimization methods such as evolutionary algorithms. However, their application to real-world Water Distribution Systems has been found to be generally limited. Future research opportunities exist through close collaboration of research institutions and Water service providers to close the gap between theory and applications. Although not ex...
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ira wds a gis based risk analysis tool for Water Distribution Systems
Environmental Modelling and Software, 2007Co-Authors: Kalanithy Vairavamoorthy, Harshal Galgale, S D GorantiwarAbstract:This paper presents the development of a new software tool IRA-WDS. This GIS-based software predicts the risks associated with contaminated Water entering Water Distribution Systems from surrounding foul Water bodies such as sewers, drains and ditches. Intermittent Water Distribution Systems are common in developing countries and these Systems are prone to contamination when empty. During the non-supply hours contaminants from pollution sources such as sewers, open drains and surface Water bodies enter into the Water Distribution pipes through leaks and cracks. Currently there are no tools available to help engineers identify the risks associated with contaminant intrusion into intermittent Water Distribution Systems. Hence it is anticipated that IRA-WDS will find wide application in developing countries. The paper summarises the details of the mathematical models that form the basis of IRA-WDS. It also describes the software architecture, the main modules, and the integration with GIS using a tight coupling approach. A powerful GUI has been developed that enables data for the models to be retrieved from the spatial databases and the outputs to be converted into tables and thematic maps. This is achieved seamlessly through DLL calling functions within the GIS. This paper demonstrates the application of the software to a real case study in India. The outputs from IRA-WDS are risk maps showing the risk of contaminant intrusion into various parts of the Water Distribution system. The outputs also give an understanding of the main factors that contribute to the risk.
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Water safety plans book 4 ira wds software and manual for risk assessment of contaminant intrusion into Water Distribution Systems
Water safety plans: Book 4. IRA-WDS software and manual for risk assessment of contaminant intrusion into water distribution systems., 2006Co-Authors: Kalanithy Vairavamoorthy, S D Gorantiwar, Harshal GalgaleAbstract:This book has been written specifically for practitioners involved in the operation, maintenance and management of piped Water Distribution Systems in urban areas of developing countries. These practitioners include engineers, planners, managers, and Water professionals involved in the monitoring, control and rehabilitation of Water Distribution networks. This book is a manual for using the developed software, IRA-WDS (Improved Risk Assessment for Water Distribution Systems), a Geographical Information System (GIS) that aids in evaluating the risk of deterioration of the Water Distribution network of a Water supply system. The manual is a structured document and explains a step-by-step procedure for using the IRA-WDS, with examples. The software IRA-WDS has been developed to evaluate risks to piped Water Distribution Systems of urban areas in developing countries. This manual enables the use of this software. The software consists of three models, namely the Contaminant Ingress Model, Pipe Condition Assessment Model and Risk Assessment Model. The IRA-WDS is designed to use these models together or individually. This manual provides a step-by-step procedure for using these models and obtaining results. Water Safety Plans Book 3, also developed in this series, should be used along with the software and this manual. This will enable readers to understand and analyse their results. The WEDC Water Safety Plans series comprises: Book 1: Planning Water Safety Management for Urban Piped Water Supplies in Developing Countries; Book 2: Supporting Water Safety Management for Urban Piped Water Supplies in Developing Countries; Book 3: Risk Assessment of Contaminant Intrusion into Water Distribution Systems; Book 4: IRA-WDS Software and Manual for Risk Assessment of Contaminant Intrusion into Water Distribution Systems.
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Water safety plans book 3 risk assessment of contaminant intrusion into Water Distribution Systems
2006Co-Authors: Kalanithy Vairavamoorthy, Harshal Galgale, S D Gorantiwar, S MohanAbstract:This book has been written specifically for practitioners involved in the operation, maintenance and management of piped Water Distribution Systems in urban areas of developing countries. These practitioners include engineers, planners, managers, and Water professionals involved in the monitoring, control and rehabilitation of Water Distribution networks. The book explains in detail how to evaluate the risk of deterioration of the Water Distribution network of a Water supply system. It begins with the conceptualization of risk evaluation and its three different components (hazard, vulnerability and risk). The book further elaborates on each of these three components, explains the methodologies used to estimate the components, and presents the background to the mathematical models. Finally, the book explains how these components are integrated to form a GIS-based decision support system for risk evaluation. The book is designed to help practitioners understand the concept of risk evaluation and supports the manual of the IRA-WDS software, a GIS-based decision support system for risk evaluation. The IRA-WDS software is developed for the evaluation of risk to piped Water Distribution Systems in urban areas of developing countries. The user of this software needs to know about the consideration of different factors, data type and requirement, which may vary from one region to another. The user can understand the concept of evaluation from this book and decide upon the importance of the different factors involved and associated data collection. It should be noted that combining this book with Water Safety Plans Book 1 provides the decision-maker with a valuable tool to assess the overall risk of contaminant intrusion into a Water supply system. It is also important to consider this book in relation to Water Safety Plans Book 2, as it is imperative that the institutions and authorities responsible for Water management have the capacity to use and implement IRA-WDS, and also to recognize the importance of developing an integrated approach to Water management. The WEDC Water Safety Plans series comprises: Book 1: Planning Water Safety Management for Urban Piped Water Supplies in Developing Countries; Book 2: Supporting Water Safety Management for Urban Piped Water Supplies in Developing Countries; Book 3: Risk Assessment of Contaminant Intrusion into Water Distribution Systems; Book 4: IRA-WDS Software and Manual for Risk Assessment of Contaminant Intrusion into Water Distribution Systems.
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leakage reduction in Water Distribution Systems optimal valve control
Journal of Hydraulic Engineering, 1998Co-Authors: Kalanithy Vairavamoorthy, Jeremy LumbersAbstract:The reduction of leakage is an important objective of the United Kingdom Water industry. The inclusion of pressure-dependent leakage terms in network analysis allows the application of formal optimization techniques to identify the most effective means of reducing Water losses in Distribution Systems. The development of an optimization method to minimize leakage in Water Distribution Systems through the most effective settings of flow reduction valves is described. The method shows a significant advantage compared with previously published techniques in terms of robustness and computational efficiency. A particular feature of the approach is the use of an objective function that allows minor violations in the targeted pressure requirements. This allows a much greater improvement in the exceedance of minor pressure requirements than would otherwise be achieved.
