ArticleLiterature Review

Review on water leakage control in distribution networks and the associated environmental benefits

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Abstract

Water supply is the primary element of an urban system. Due to rapid urbanization and water scarcity, maintaining a stable and safe water supply has become a challenge to many cities, whereas a large amount of water is lost from the pipes of distribution systems. Water leakage is not only a waste of water resources, but also incurs great socio-economic costs. This article presents a comprehensive review on the potential water leakage control approaches and specifically discusses the benefits of each to environmental conservation. It is concluded that water leakage could be further reduced by improving leakage detection capability through a combination of predictive modeling and monitoring instruments, optimizing pipe maintenance strategy, and developing an instant pressure regulation system. The environment could benefit from these actions because of water savings and the reduction of energy consumption as well as greenhouse gas emissions.

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... Therefore, a large number of studies were addressed to obtain a characterization of water losses to set up a number of strategies for reducing the amount of leakage and to create numerical models for the dynamic control of the network. A literature review including each of these aspects can be found in [5,6] and [7][8][9], respectively. Product innovation is in general connected to the equipment for the location of the water losses in the network, based on water balances or on local measurements. ...
... The most common EPDs are represented by the use of commercial Pumps As Turbines (PATs). A complete theory for PATs design and control in water supply networks has already been developed [12], including a detailed cost analysis [13], and a number of plants have been already installed [6,12]. The problem of system control is also important in free surface conditions. ...
Article
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The larger anthropic pressure on the Water Supply Systems (WSS) and the increasing concern for the sustainability of the large energy use for water supply, transportation, distribution, drainage and treatment are determining a new perspective in the management of water systems [...]
... Par la création de l'îlot de chaleur urbain (décrit dans la partie précédente), l'urbanisation modifie les conditions climatiques locales, ce qui se traduit par une augmentation de la température en ville par rapport aux surfaces rurales environnantes (Oke, 1982 ;Santamouris, 2015). Ceci peut contribuer à l'augmentation de l'évaporation du sol, dont la source d'humidité peut être dans certains cas assurée localement par les fuites récurrentes dans les réseaux d'eau potable (Xu et al., 2014). En outre, l'augmentation de la température conjuguée à la sur-irrigation des espaces verts urbains contribue à l'augmentation de la transpiration (Salvador, Bautista-Capetillo et Playán, 2011). ...
... En revanche, la diminution de la recharge peut être compensée par la diminution de l'évapotranspiration réelle (par réduction du couvert végétal), par l'irrigation des espace verts urbains ou par la mise en place de techniques alternatives (voir le récapitulatif ci-dessous) permettant de ré-infiltrer les volumes ruisselés suite aux événements pluvieux (Göbel et al., 2004 ;Hamel, Daly et Fletcher, 2013 ;Shuster, Gehring et Gerken, 2007). La recharge souterraine bénéficie également des fuites d'eau qui arrivent souvent dans les canalisations d'eau potable (Appleyard, 1995 ;Kim, Lee et Sung, 2001 ;Xu et al., 2014 ;Lerner, 2002 ;Yang et al., 1999), voire dans les réseaux d'assainissement (Wakode et al., 2018). Des puits d'injection peuvent également être utilisés pour garantir une recharge artificielle (Lerner, 1990). ...
Thesis
Afin de déterminer l'impact hydrologique de l'étalement urbain à venir, la modélisation hydrologique est très utile car elle permet de traduire les scénarios d'urbanisation en scénarios hydrologiques en tenant compte de la variabilité climatique. Malgré la diversité actuelle des modèles hydrologiques applicables sur les bassins urbanisés, ces modèles sont en général développés sur un nombre limité de bassins versants, ce qui pose la question de leur robustesse. L'objectif de cette thèse est de chercher une structure de modèle hydrologique capable de reproduire la relation pluie-débit pour un large échantillon de bassins versants urbanisés, situés en France et aux États-Unis, et caractérisés par différents niveaux d'étalement urbain. Pour ce faire, nous sommes partis d'une structure de modèle conceptuel (GR4H), fonctionnant au pas de temps horaire mais non dédiée aux bassins versants urbanisés. Pour arriver à nos objectifs, nous avons considéré quatre étapes : (1) la collecte et la préparation d'un large échantillon de données pour plus de 2000 bassins versants situés en France et aux États-Unis. L'analyse de la variabilité des coefficients de ruissellement de 852 bassins nord-américains a montré une dépendance non seulement au taux moyen d'imperméabilité totale (TIA), mais aussi aux conditions d'humidité du sol quel que soit le niveau d'étalement urbain du bassin versant ; (2) le test de la structure de départ sur les bassins fortement urbanisés. Cette étape a montré l'aptitude des paramètres du modèle GR4H à traduire les spécificités du comportement hydrologique en contexte urbanisé ; (3) la régionalisation des paramètres de la structure de départ GR4H pour les lier à la fraction du couvert urbain. Les relations de régression obtenues ont été performantes mais peu sensibles à la caractérisation du couvert urbain ; (4) la modification pas-à-pas de la structure de GR4H en rajoutant le ruissellement sur les surfaces imperméables, et en variant le partage entre écoulement rapide et écoulement lent en fonction de chaque bassin. L'évaluation de ces modifications sur 273 bassins versants urbanisés a indiqué une amélioration de la simulation des écoulements surtout lors des périodes sèches et des périodes de crue. Les paramètres rajoutés ont montré une forte dépendance au taux moyen d'imperméabilité totale. Les travaux de cette thèse montrent un exemple de démarche constructive de développement de modèle hydrologique, par laquelle nous avons réussi à améliorer la représentation de l'urbanisation au sein du modèle tout en obtenant de meilleurs résultats en comparant avec des séries observées. Un effort de régionalisation de la nouvelle structure en exploitant des mesures de fragmentation du paysage urbain permettra une étude d'impact de différents schémas d'urbanisation future sur la réponse hydrologique.
... Water supply is the primary element of an urban system. Due to rapid urbanization and water scarcity, maintaining a stable and safe water supply has become a challenge to many cities [107]. The increasing urban development and poorly managed agricultural areas have the most adverse effects on source water quality [108]. ...
... Water leakage is not only a waste of water resources, but also incurs great socio-economic costs. Firstly, water leakage could be further reduced by improving leakage detection capability with a combination of predictive modeling and monitoring instruments, optimizing pipe maintenance strategy, and developing an instant pressure regulation system [107]. The environment could benefit from these actions because of water savings and the reduction of energy consumption as well as greenhouse gas emissions. ...
... This solution is often favored by managers because it gives effective results and avoids structural interventions such as pipeline revamping, which is often difficult to realize in urban areas. A clear review of the methods for leakage control can be found in [2], where pressure management is identified as the only method that can effectively reduce background leakage. Some researchers have been looking for procedures to find the best placement of PRVs in a network [3][4][5][6][7][8][9][10] to obtain maximum effectiveness from the operation; others have incorporated leakage terms and effects of valve control in the same network model [11][12][13][14] to find the best solution. ...
... The scale effect on efficiency is neglected in this sizing procedure. Knowing the average flow coefficient required by the site (calculated by PRV average working conditions of Table A1), the required GVS diameter can be calculated by using Equation (2). The efficiency should then be reduced to take into account the loss due to energy transformation caused by the generator. ...
Article
Full-text available
In recent years, water utilities have made worldwide investments targeted to the implementation of an effective monitoring system and the installation of pressure-reducing valves in strategic nodes of water distribution networks. In fact, these interventions are considered fast and effective solutions to address at least two main concerns of modern water utilities: leakage reduction and energy efficiency. The present paper, on the basis of a database of working conditions of installed pressure-reducing valves, discusses the range of applicability of the GreenValve system (GVS) as an alternative solution to improving standard pressure-reducing valve capabilities. The device is able to recover energy, and it can be used to create a stand-alone monitoring node with remote control ability, optimizing the network from an energetic, functional, and hydraulic point of view.
... The situation is even more critical in small municipalities from developing countries that have limited financial resources and lack of technical and decision support tools (Mazzolani et al. 2017). This makes it difficult to collect the information required to quantify and understand the magnitude of the water-loss phenomenon, assess the costs and benefits of technical and managerial strategies, and thus, prioritize investments (Xu et al. 2014). ...
... Even when the accuracy of the results from this study can be improved with future research, this attempt helped to identify needs for information, infrastructure, monitoring, maintenance, and administration to improve the understanding and quantification of the water-loss magnitude and its components. In addition, progress on environmental valuation associated with water losses due to leakage should start to be included in these analyses (Xu et al. 2014). ...
Article
Urban areas are facing challenges for the provision of public services, with water scarcity arising as one of the main problems. A twin track approach of supply and demand management is essential, and water-loss management contributes to reducing water demand. However, small municipalities from developing countries have technical, information, and financial limitations to locate and monitor water losses. This paper presents the estimation of real and apparent losses in a small municipality from a developing country in a data-scarce situation. For this, several tools were used, allowing data integration that resulted in a water balance, from which water losses were estimated at 46%, and four alternatives for water-loss reduction were developed. A cost-benefit analysis and financial indicators were estimated for the proposed alternatives, resulting in a water savings of 19%, a payback period of 3 years and an internal rate of return of 39%. The proposed strategies have potential to improve water quantity and quality, the technical stability of the system, utility performance, and water security.
... In buildings, water loss is very common and is usually caused by leaks in bathrooms and hydraulic equipment. These losses verified in water distribution systems are usually the result of incorrect maintenance procedures, bad habits of the users and errors of design (Gois et al., 2015), and they may reach between 10% and 70% of the distributed water (Xu et al., 2014). ...
... Gheisi et al. [41] classified the mathematical methods of WDN reliability into three groups (i.e., analytic approach, systemic-holistic approach, and heuristic approach) by focusing on the failure methods. Xu [42] reported potential approaches for water-leakage control and their benefits in terms of environmental conservation. Shin et al. [11] reviewed quantitative approaches with respect to the water infrastructure systems, including the water resource and distribution systems. ...
Article
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Water distribution networks (WDNs) are critical contributors to the social welfare, economic growth, and public health in cities. Under the uncertainties that are introduced owing to climate change, urban development, aging components, and interdependent infrastructure, the WDN performance must be evaluated using continuously innovative methods and data acquisition. Quantitative resilience assessments provide useful information for WDN operators and planners, enabling support systems that can withstand disasters, recover quickly from outages, and adapt to uncertain environments. This study reviews contemporary approaches for quantifying the resilience of WDNs. 1508 journal articles published from 1950 to 2018 are identified under systematic review guidelines. 137 references that focus on the quantitative resilience methods of WDN are classified as surrogate measures, simulation methods, network theory approaches, and fault detection and isolation approaches. This study identifies the resilience capability of the WDNs and describes the related terms of absorptive, restorative, and adaptive capabilities. It also discusses the metrics, research progresses, and limitations associated with each method. Finally, this study indicates the challenges associated with the quantification of WDNs that should be overcome for achieving improved resilience assessments in the future.
... The economic dimension of water distribution networks has been addressed considering aspects as cost of treatment intended for human consumption [11] or for sanitary use [12], cost of pipelines [13], maintenance of the network [14], pumping [15], efficiency in energy consumption [16], cost of utilities [17] and cost of extraction [18]. The environmental dimension has considered the life cycle assessment analysis [19], emissions generated by system [20] and reducing water losses [21]. The social dimension has focused on improving the behavior of the final user [22], final usage [23] and conflicts in the distribution between different communities and users [24]. ...
Article
This paper presents an approach for designing power and water distribution networks involving the sizing, geographic location, as well as the economic, environmental and social impacts, and taking into account the multiplicity of criteria for the stakeholders involved in the development of operational policies and new facilities. In this paper is presented a method for defining solutions concerning to the design of power and water distribution networks based on a multi-stakeholder environment. A multi-objective model, considering economic, environmental and social factors, is used for illustrating how the different criteria, about priorities of the stakeholders, affect the design of the system and how to propose a solution for achieving a tradeoff between the multiple stakeholders. The proposed method was applied to an electric and water stressed scheme in the north of Mexico, the results show that the minimization of the dissatisfaction of the involved systems can provide an optimal solution that meets the objectives of all stakeholders.
... Besides the energy savings, pressure control for WDS can significantly improve the pipe network's safety, because high pressure and pressure fluctuations usually lead to more pipe breaks and water loss (Lambert, 2001). Therefore, many researchers have studied ways to control water pressure in pipe networks and achieved promising results (Araujo et al., 2006;Martínez et al., 2007;Nicolini and Zovatto, 2009;Salomons et al., 2007;Xu et al., 2014a;Xu et al., 2014b). The effect of type selection, installation position and installation number of PRVs on reducing pipe leakage and loss has also been analyzed and discussed (Fantozzi et al., 2009;Meyer et al., 2009). ...
... However, the prevalence of leaks in water supply pipelines makes this situation face greater challenges. According to Xu [3], about 35% of the world's fresh water resources are wasted in the water supply process. Hence, various sensors and control equipment must be arranged along the water supply pipeline to achieve real-time monitoring and remote control of the leakage [4]. ...
Article
Solving the problem of continuous and stable power supply for the water leakage monitoring equipment is challenging in water supply system. Due to the excess water pressure existing in the water supply pipes, the hydropower inside the pipes becomes an effective renewable energy for supplying power to water leakage monitoring equipment. In this paper, a vertical drag-type runner is integrated into the ball valve to harvest the potential hydropower while regulating the fluid. Numerical investigation of the novel ball valve (referred to as GreenValve) is carried out using the software FLUENT. According to different performance requirements, the best working parameters at the average flow rate of 15.7 × 10⁻³ m³/s are obtained: when working at the optimal tip speed ratio, the GreenValve performs best within the relative opening range of 25%–39%, in which it can harvest considerable energy (>80 W) with the highest efficiency (>11.5%) while the water head loss is only 4–12 m. For the water supply system, the water head loss due to the impact of energy harvesting by the GreenValve can be used to offset the excess pressure in pipes which can easily cause leakage of the pipe network system.
... Several methods can be used to detect water leaks (Hunaidi et al., 2000;Hao et al., 2012;Liu and Kleiner, 2013;Puust et al., 2010) but the choice of the most suitable one depends on the specific case at hand. In general, the water supply companies determine the district metered area (DMA) to inspect as a priority by observing at night the water flow measured by dataloggers located at the entry and the exit of the network districts (Farley and Trow, 2003;Savić and Ferrari, 2014;Xu et al., 2014). Once a potential leak is detected, tools aiming at reducing the investigation area can be employed. ...
... Several methods can be used to detect water leaks (Hunaidi et al., 2000;Hao et al., 2012;Liu and Kleiner, 2013;Puust et al., 2010) but the choice of the most suitable one depends on the specific case at hand. In general, the water supply companies determine the district metered area (DMA) to inspect as a priority by observing at night the water flow measured by dataloggers located at the entry and the exit of the network districts (Farley and Trow, 2003;Savić and Ferrari, 2014;Xu et al., 2014). Once a potential leak is detected, tools aiming at reducing the investigation area can be employed. ...
... However, an important issue whether leakage undermines sustainability remained unanswered and very dependent on methodology (level of water scarcity, the impact on environment, consumers' perception). The existing evaluation practices don't reflect long-term sustainability of the water environment, nor social (Social considerations mostly refer to (1) unsustainable resort to scarce water resources; (2) carbon emissions from increased energy consumption in the process of drinking water provision; (3) risk of contamination due to poor infrastructure [8]) or financial considerations. There were some attempts to include externalities and concept of SELL (Sustainable Economic Level of Leakage) has been developed [9,10]. ...
Article
Full-text available
Water losses are in focus of water supply management in last decades. Basic and widely accepted indicator is ILI Index, but is insufficient, when water resources are abundant, treatment costs low and energy consumption miniscule due to gravity. In such situation several authors introduced more detailed analysis defining “Economic Level of Leakage” (ELL) in short run. This analysis provides an insight into shadow market of leakages that is defined by marginal cost of water supplied on supply side and by marginal cost of repairs to mitigate water loss on demand side and provide empirical example based on real water supply system (WSS) data.
... The economic dimension of water distribution networks has been addressed considering aspects as cost of treatment intended for human consumption [11] or for sanitary use [12], cost of pipelines [13], maintenance of the network [14], pumping [15], efficiency in energy consumption [16], cost of utilities [17] and cost of extraction [18]. The environmental dimension has considered the life cycle assessment analysis [19], emissions generated by system [20] and reducing water losses [21]. The social dimension has focused on improving the behavior of the final user [22], final usage [23] and conflicts in the distribution between different communities and users [24]. ...
Chapter
This paper presents a systematic approach to synthesize optimal water distribution networks (WDN) taking into account the water requirement of consumers based on a multi-stakeholder approach. A structural representation is developed to satisfy the water requirements of all users without taking into account water concessions in the region, but considering the depletion of groundwater and surface water, to generate an integral water distribution network. A rigorous mathematical formulation is developed as a mixed-integer linear programming model to transform the water distribution problem into an optimization task that seeks to minimize the overall cost of the water supply network. The proposed optimization model was applied to the Sonoran water scarcity problem from Mexico, where the optimal water distribution network was obtained, based on a multi-criteria approach taking into account the industrial, domestic and agricultural users. The obtained results show that the proposed model can satisfy economic, environmental and social aspects, where the distribution of water is equal for all users without affecting natural resources. Also, the results show economic advantages due to the sales of water.
... Previous studies reviewed various LDTs and highlighted their specific advantages, limitations, and suitability to different application scenarios. While a majority of these studies focused on LDTs in general ( Costello et al., 2007;Colombo et al., 2009;Thomson and Wang, 2009;Ahadi and Bakhtiar, 2010;Puust et al., 2010;Kleiner, 2012, 2013;Cataldo et al., 2014;Xu et al., 2014;Deepak et al., 2016;Atef et al., 2016;Abdulshaheed et al., 2017), some specifically focused on acoustics-based techniques (Nestleroth et al., 2012;Hunaidi, 2012;Ismail et al., 2014;Anguiano et al., 2016;Martini et al., 2016). The acoustics-based leak detection techniques (hereafter referred as ALDTs), which are widely used in practice, rely on the premise that a leak induces noise or a vibration signal that travels through the pipe wall or the water column and that this signal can be detected using appropriate sensing equipment. ...
Article
Full-text available
Purpose There has been a sustained interest over the past couple of decades in developing sophisticated leak detection techniques that are economical and reliable. Majority of current commercial leak detection techniques are acoustics-based and they are not equally suitable to all pipe materials and sizes. There is also limited knowledge on the comparative merits of such acoustics-based leak detection techniques (ALDTs). The purpose of this paper is to review six commercial ALDTs based on four decisive criteria and subsequently develop guidance for the optimal selection of an ALDT. Design/methodology/approach Numerous publications and field demonstration reports are reviewed for evaluating the performance of various ALDTs in this study to inform their optimal selection using an integrated multi-criteria decision analysis framework. The findings are validated using interviews of water utility experts. Findings The study approach and the findings will have a broad impact on the water utility industry by identifying a suite of suitable ALDTs for a range of typical application scenarios. The evaluated ALDTs include listening devices, noise loggers, leak-noise correlators, free swimming acoustic, tethered acoustic, and acoustic emissions. The evaluation criteria include cost, reliability, access requirements, and the ability to quantify leakage severity. The guidance presented in this paper will support efficient decision making in water utility management to minimize pipeline leakage. Originality/value This study attempts to address the problem of severe dearth of performance data for pipeline inspection techniques. Performance data reported in the published literature on various ALDTs is appropriately aggregated and compared using a multi-criteria decision analysis, while the uncertainty in performance data is addressed using the Monte-Carlo simulation approach.
... Not only is leakage from distribution pipes a wastage of water resources, but also it includes environmental resources and social and economic losses and can potentially allow harmful contaminates into the water. Because of leakages and pipe failures, a significant amount of water is lost during supply to customers [1]. All over the world, more than 32 billion m 3 of potable water is lost, which is greater than 35% of total water supplied [2]. ...
Article
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Traditionally permanent acoustic sensors leak detection techniques have been proven to be very effective in water distribution pipes. However, these methods need long distance deployment and proper position of sensors and cannot be implemented on underground pipelines. An inline-inspection acoustic device is developed which consists of acoustic sensors. The device will travel by the flow of water through the pipes which record all noise events and detect small leaks. However, it records all the noise events regarding background noises, but the time domain noisy acoustic signal cannot manifest complete features such as the leak flow rate which does not distinguish the leak signal and environmental disturbance. This paper presents an algorithm structure with the modularity of wavelet and neural network, which combines the capability of wavelet transform analyzing leakage signals and classification capability of artificial neural networks. This study validates that the time domain is not evident to the complete features regarding noisy leak signals and significance of selection of mother wavelet to extract the noise event features in water distribution pipes. The simulation consequences have shown that an appropriate mother wavelet has been selected and localized to extract the features of the signal with leak noise and background noise, and by neural network implementation, the method improves the classification performance of extracted features.
... To solve this issue, the pressure of the pumping stage should be arisen, which makes the water leakage worse, as well as more electricity will be consumed by the water pumps [14]. The water leakage detection tools reduce the energy requirement of the water distribution systems [15]. Authors of [16][17][18] proved that the ocean thermal energy conversion based binary cycle generates the electrical power and desalted water. ...
Article
Recently, seawater desalination and power generation units are optimally co-scheduled because of interconnection between electricity and water networks. A typical water-energy hub grid consists of the conventional thermal power plants and the combined water and power (CWP) generating units. In the CWP plants, the waste heat of the flue gases exhausted from the power generation process is utilized for water treatment. If the water and power generation company aims to maximize its daily profit, the electricity price uncertainty will affect the optimum operating point of the generating units. In other words, the fluctuations of the energy prices cause the power generation patterns of thermal and CWP units to change. Hence, this paper implements a robust optimization strategy on water-power nexus model to handle the uncertainty of the electricity price with no need for its probability distribution and membership functions. The lower and upper bounds and the forecasted prices are used for solving the robust mixed-integer non-linear program and making the risk-averse decisions against the uncertainty. It is indicated that the proposed approach is suitable for the price taker water-power cogeneration companies, which seek the optimal schedule of their thermal and CWP units for a certain operating period.
... No matter whether medium transported in the pipeline is drinking water, oil or some other harmful substances, the leakage problem will lead to serious consequences [1]. Taking the leakage problem of water supply system as an example, according to literature [2], the water loss caused by pipeline leakage accounts for about 35% of the total water supply quantity. The water supply situation is becoming increasingly severe [3]. ...
Article
Full-text available
Integrating vertical-axis runners into ball valves for energy harvesting from pressurized pipes in water supply systems has become a promising scheme of self-supplying power (referred to as the “GreenValve” scheme). In addition to energy harvesting, the GreenValve configuration also has the function of fluid regulating, which makes a qualitative breakthrough in both structure and function. However, the runner specially used to match the ball valve has not been fully studied and designed. Hence, based on the traditional Savonius rotor, a modified semi-elliptical runner is proposed in this study. To better match the ball valve structurally, the roundness of the runner at blade tip position is improved and, thus, the initial runner configuration is obtained. Moreover, research on blade profile flatness and runner aspect ratio is conducted in FLUENT software to be more functionally compatible with the ball valve. Numerical results indicate that the GreenValve always performs best in terms of shaft power at 25% opening regardless of the aspect ratio and the flatness. When the flatness value is equal to 0.7, the GreenValve presents the maximum shaft power and the second highest flow coefficient which is only 1.9% lower than the maximum value. Comparison results of three models with different aspect ratios reveal that the model with the smallest aspect ratio has a slight reduction in flow capacity while a significant improvement in shaft power, reaching a maximum shaft power of 78.6W.
... Gomes et al. (2013) studied on the influence of different relationships between pressure and leakage in water distribution systems and could show the benefit yielded by pressure management. Xu et al. (2014) reviewed the potential water leakage control approaches and specifically discussed the benefits of each to environmental conservation. They concluded that water leakage is further reduced by improving leakage detection capability via a combination of predictive modeling and monitoring instruments, optimization of pipe maintenance strategy, and development of an instant pressure regulation system. ...
Article
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Pressure management is one of the most significant water demand management methods to reduce leakage in water distribution networks. Leak as an adverse event is directly related to the pressure. Therefore, reducing extra network pressure decreases leakage in water distribution networks. The pressure reducing valves have some disadvantage. For example, they break down quickly. Therefore, in this study, a novel system named Pressure Reducing Flexible Storage (PRFS) was introduced that hasn’t these disadvantages and it could consider a good alternative for pressure reducing valves in water distribution networks. In this system, a spherical tank containing a flexible rubber cover was installed at the network node. By increasing the pressure in the conjunction, the foam was compressed and reduced the pressure. In this study, the presented system was simultaneously modeled by using Flow-3D and ABAQUS softwares, and pressure decrement was estimated in the conjunction. The results show that the proposed system can decrease the pressure in the conjunctions of water distribution network by about 18%. Therefore, it could be considered as a good alternative for pressure reducing valves in water distribution networks.
... One drawback of these water supply systems is the increase in network pressure in some areas, which causes the pipeline to leak and burst during the delivery process. The annual loss of freshwater leakage worldwide is estimated at over 32 billion m 3 [1]. ...
Article
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The excess hydraulic pressure in water supply network pipes is one of the major problems in design and implementation stages of these projects. To reduce the excess pressure and maintain network safety, a variety of pressure reducing valves are used, which waste all the excess pressure. However, having used the appropriate water microturbines, while reducing the pressure loss to an optimum value, the system could recover the wasted energy. In this study, numerical simulation and experimental investigation of microturbine in a water supply system have been performed to evaluate the electrical power generation capacity of an over-pressured network. The numerical simulation of the microturbine was conducted using Ansys-Fluent software. The microturbine has been experimentally investigated with different inlet flow rates, the effect of different post-microturbine heads and also the effect of different opening angles of guide plate on its performance, three different scenarios were defined. Based on numerical simulation and laboratory results, the best performance of the microturbine was obtained when the inlet flow rate was 0.01184 m 3 /s and also opening angle 20° for the guide plate, in which the microturbine output was equal to 59.01 W. The generated power by the microturbine can meet the electrical needs of sensors and other network monitoring equipment.
... Water infrastructure, especially in cities, can be outdated or reach the end of the service life, causing leakage problems and therefore contributing to increased levels of water abstraction (Goulet et al., 2013;Wan Alwi et al., 2014). Losses of water (or non-revenue water) in the distribution network can reach high percentages, between 10 to 70 % of the water distributed (Xu et al., 2014 loss. An effective reduction in leakage rates to an acceptable level depends on a number of factors. ...
Article
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Currently, more research to implement and monitor cleaner production practices for distribution and sustainable management of natural and alternative water sources to comply with the demands of the different users while preserving water levels are needed. In this paper, a periodic hourly-based model with meaningful parameters has been developed to analyze and forecast water demand as a function of time, thus enabling a better understanding of the consumption pattern and the condition of the pipe network. The model was tested by investigating the daily water consumption from selected categories of users which were isolated from different distribution networks in Sligo, Ireland. The flow data used was obtained in 15-min intervals and averaged in different time periods for analysis. In all cases, the model fittings obtained were highly consistent and all the parameters showed satisfactory confidence intervals (α=0.05), thus demonstrating the reliability of this approach. The model provides a quick analysis revealing the regularities of water demand that could benefit water utility managers and researchers: to obtain optimal regulation and pumping schemes; for planning and design purposes; to control unexpected scenarios that can take place during the distribution of water; the performance of water distribution systems; and to locate possible network failures. In addition, the model parameters can be used as standard criteria for water utilities to compare precisely the water demand between different areas, identify complex trends and analyze the pipe network for managing, auditing and monitoring purposes. DOWNLOAD FULL PAPER FROM http://researchrepository.ucd.ie/handle/10197/6757
... Monitoring and maintenance of system components such as pipelines is crucial for the reliability of water treatment and supply Xu et al., 2014;Asghari et al., 2018) as well as its sustainability and resilience (Boulos, 2017). Identifying the root causes of corrosion in pipelines is key for timely and successful monitoring and maintenance plans. ...
Article
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Water pipe corrosion inflicts big health problems and financial damages to societies. Temperature, pH, type, and dosage of oxidants, and DO are some of the key factors that affect water pipe corrosion. The aim of this research is to assess the impacts of temperature (15 and 25oC), dosage of potassium permanganate (0, 1 and 2 mg/L) and sodium hypochlorite (0, 0.5 and 1 mg/L) on corrosion of steel pipes. To measure the corrosion of steel specimens, OCP, EIS and potentiodynamic polarization tests were conducted. The results showed a direct relationship between temperature and corrosion rate. A 10-degree raise in the temperature, caused a 25% increase in corrosion current density (CCD). Adding sodium hypochlorite to the solution, decreases CCD by around 50%. Moreover, potassium permanganate proved to have a positive impact on reducing CCD by up to 21%. The results demonstrate that simultaneous usage of NaClO and KMnO4 for water disinfection can have beneficial impact on corrosion of steel pipes. Finally, our analysis suggests that when combined with KMnO4, lower dosage of NaClO significantly increases polarization resistance. The findings of this research highlight the impact of disinfectants on steel water pipes corrosion in different temperatures and supports water infrastructure decision-makers in more effective rehabilitation and maintenance of water pipes. Further, our results inform decision-makers for a more effective infrastructure design and resilience planning to random failures caused by corrosion.
... It has been determined that water loss may be further decreased by increasing leak-detecting capabilities. These measures may support the environment by saving water and reducing both energy and greenhouse gas emissions [4]. ...
Article
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Due to the constant need to enhance water supply sources, water operators are searching for solutions to maintain water quality through leakage protection. The capability to monitor the day-to-day water supply management is one of the most significant operational challenges for water companies. These companies are looking for ways to predict how to improve their supply operations in order to remain competitive, given the rising demand. This work focuses on the mathematical modeling of water flow and losses through leak openings in the smart pipe system. The research introduces smart mathematical models that water companies may use to predict water flow, losses, and performance, thereby allowing issues and challenges to be effectively managed. So far, most of the modeling work in water operations has been based on empirical data rather than mathematically described process relationships, which is addressed in this study. Moreover, partial submersion had a power relationship, but a total immersion was more likely to have a linear power relationship. It was discovered in the experiment that the laminar flows had Reynolds numbers smaller than 2000. However, when testing with transitional flows, Reynolds numbers were in the range of 2000 to 4000. Furthermore, tests with turbulent flow revealed that the Reynolds number was more than 4000. Consequently, the main loss in a 30 mm diameter pipe was 0.25 m, whereas it was 0.01 m in a 20 mm diameter pipe. However, the fitting pipe had a minor loss of 0.005 m, whereas the bending pipe had a loss of 0.015 m. Consequently, mathematical models are required to describe, forecast, and regulate the complex relationships between water flow and losses, which is a concept that water supply companies are familiar with. Therefore, these models can assist in designing and operating water processes, allowing for improved day-to-day performance management.
... It has been determined that water loss may be further decreased by increasing leak-detecting capabilities. These measures may support the environment by saving water and reducing both energy and greenhouse gas emissions [4]. ...
Article
Due to the constant need to enhance water supply sources, water operators are searching for solutions to maintain water quality through leakage protection. The capability to monitor the day-today water supply management is one of the most significant operational challenges for water companies. These companies are looking for ways to predict how to improve their supply operations in order to remain competitive, given the rising demand. This work focuses on the mathematical modeling of water flow and losses through leak openings in the smart pipe system. The research introduces smart mathematical models that water companies may use to predict water flow, losses, and performance, thereby allowing issues and challenges to be effectively managed. So far, most of the modeling work in water operations has been based on empirical data rather than mathematically described process relationships, which is addressed in this study. Moreover, partial submersion had a power relationship, but a total immersion was more likely to have a linear power relationship. It was discovered in the experiment that the laminar flows had Reynolds numbers smaller than 2000. However, when testing with transitional flows, Reynolds numbers were in the range of 2000 to 4,000. Furthermore, tests with turbulent flow revealed that the Reynolds number was more than 4000. Consequently, the main loss in a 30 mm diameter pipe was 0.25 m, whereas it was 0.01 m in a 20 mm diameter pipe. However, the fitting pipe had a minor loss of 0.005 m, whereas the bending pipe had a loss of 0.015 m. Consequently, mathematical models are required to describe, forecast, and regulate the complex relationships between water flow and losses, which is a concept that water supply companies are familiar with. Therefore, these models can assist in designing and operating water processes, allowing for improved day-today performance management. Citation: Altowayti, W.A.H.; Othman, N.; Tajarudin, H.A.; Al-Dhaqm, A.; Asharuddin, S.M.; Al-Gheethi, A.; Alshalif, A.F.; Salem, A.A.; Din, M.F.M.; Fitriani, N.; et al. Evaluating the Pressure and Loss Behavior in Water Pipes Using Smart Mathematical Modelling. Water 2021, 13, x. Publisher's Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.
... The division of WDN into DMAs is interesting to WSS managers. In fact, it reduces costs with leaks, pipe ruptures and wasted electricity [139]. In addition, approximately 75% of WSSs are oversized in relation to real demand [140]. ...
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Recent studies recommended the recovery of energy incorporated to water distribution networks (WDNs) of municipal water supply systems (WSS) through systems based on pumps-as-turbines (PATs). Although a simple and economically viable technology, it has received scanty attention in the literature when compared to other renewable energies, with subsequent limits in its understanding for academic and professional purposes. Current paper reviews the potential of WDNs in energy recovery studies using PAT technology and focuses on efficient management and control of pressure in networks and on the manner pressure-reducing valves (PRVs) wastes energy which may be retrieved when PAT is employed: key technical and challenging criteria of PATs in WDNs. Finally, a case study of a WDN with an estimate of 370,835.70 kWh/year recoverable by PATs is presented. It is expected that current paper will further PAT investigations and contribute towards PAT improvement and consolidation for sustainable use of water in WDNs and the recovery of clean energy.
... There is a vast literature on the risk-based optimal replacement and inspection planning of drinking water systems; Xu et al. (2014) provide a review on these methods. These models take in estimates of per-asset risk and determine which assets to address and how often (Chen, Riley, et al., 2020). ...
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Risk assessment is an effective tool for revealing criticalities across an entire water system. However, standard outputs that report risk at the individual pipe segment level can have limited use for decision support since utilities typically plan for the replacement of aggregated areas to minimize disruption and cost. This research presents a process for aggregating individual pipes into high‐risk clusters. Each cluster is a group of contiguous pipe which, when targeted, will reduce mobilization cost and community disruption. A graph search is first used to locate potential clusters, and then the optimal selection, which maximizes risk capture, is identified. An integer programming model is presented, and the process is implemented on a real system. Empirical trials suggest that the ability to prevent future breaks is not significantly reduced when prioritizing clusters rather than individual pipes. This shows that the proposed method can guide more cost‐efficient planning for pipe replacements. A method is presented to identify contiguous clusters of high‐risk individual pipes and optimize their selection for maximum risk reduction.
... Such tools range from machine learning and evolutionary algorithms to rule-based and knowledgebased systems. For example, supervised machine learning techniques have been used with success in complex problems, for binary and multi class classification [3]. This is useful in order to detect different faulty scenarios in complex systems using for example, on-line data from Supervisory Control and Data Acquisition (SCADA) systems. ...
Conference Paper
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Leak detection and isolation (LDI) is a problem of interest for water management companies and their technical staff. Main reasons for this are that early detection of leakages can reduce dramatically (1) water losses in urban networks and (2) the environmental burden due to wasted energy used in the system supply [1]. Water leakage can become a very complex problem, due to the lack of information about the water system and because a leak might not be easily detected on-sight. Such leaks typically appear due to ageing pipes and networks’ shortcomings; it is estimated that water losses in urban networks for example, can reach percentages up to 40%. Therefore, any diagnostic tool that could help in such task are valuable for engineers and managers. Soft computing tools have shown to be valuable tools for researchers in different fields. Such tools range from machine learning and evolutionary algorithms to rule-based and knowledgebased systems. For example, supervised machine learning techniques have been used with success in complex problems, for binary and multi class classification [2]. This is useful in order to detect different faulty scenarios in complex systems using for example, on-line data from SCADA systems. Therefore, their usage for LDI is appealing for the research community. The aim of this paper is twofold: on the one hand, to provide a review on soft computing techniques used for LDI in urban networks. On the other hand, to identify strengths and drawbacks among differentmachine learning techniques for such task in real-time acquisition scenarios. Techniques under study are principal component analysis (PCA), support vector machines (SVM) and relevance vector machines (RVM). With the provided study, it will be possible to state a common benchmark in order to evaluate different supervised machine learning techniques for LDI in urban networks and therefore encouraging new soft computing developments for such task.
... Due to the importance of identifying and reducing water losses, many papers describing technical procedures to control leakage have been published (e.g., Marques and Monteiro, 2003;Xu et al., 2014;. From an economic point of view, the most important component of the leakage control strategy is setting a target for the Economic Level of Leakage (ELL). ...
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Water scarcity is one of the main problems faced by many regions in the XXIst century. In this context, the need to reduce leakages from water distribution systems has gained almost universal acceptance. The concept of sustainable economic level of leakage (SELL) has been proposed to internalize the environmental and resource costs within economic level of leakage calculations. However, because these costs are not set by the market, they have not often been calculated. In this paper, the directional-distance function was used to estimate the shadow price of leakages as a proxy of their environmental and resource costs. This is a pioneering approach to the economic valuation of leakage externalities. An empirical application was carried out for the main Chilean water companies. The estimated results indicated that for 2014, the average shadow price of leakages was approximately 32% of the price of the water delivered. Moreover, as a sensitivity analysis, the shadow prices of the leakages were calculated from the perspective of the water companies' managers and the regulator. The methodology and findings of this study are essential for supporting the decision process of reducing leakage, contributing to the improvement of economic, social and environmental efficiency and sustainability of urban water supplies.
... Sewer exfiltration models can broadly be grouped into data-driven or process-based categories based on model applications (Table 4). In general, none of the available model approaches provides a single solution to the major issues in sewer exfiltration from site-specific to large scales, and all models are study-dependent because of the inherent complexity of pipe sewer exfiltration processes, the difference in pipe network conditions, and data availability within the study context (Xu et al., 2014a). ...
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Increasing evidence from studies in urban wastewater systems proves that sewer exfiltration may present a profound threat for rising levels of toxic substances and microbial pollution in groundwater. New and innovative methods for monitoring sewage exfiltration are continuously developed, which provide a solicit ground for a better understanding of key processes and influencing characteristics of sewer exfiltration to support the development of mathematical equations and models worldwide. However, modelling of sewer exfiltration and its associated impacts on groundwater are still constrained and not fully understood in large urban systems. This paper reviews the knowledge advancements and challenges of sewer exfiltration modelling. Based on the present review, we define five key research domains for developing more generic framework of large-scale models. These domains inquire to advance the representation of hydraulic modelling (e.g. testing exfiltration models coupled with biofilm growth models), modelling of solutes originating from sewer leakages (e.g. heavy metals), define the practical values of key model parameters of main model components and sub-processes for calibration and uncertainty evaluations, develop upscaling approaches for integrated multi-dimensional sewer exfiltration models, and incorporation of sewer exfiltration from private sewers.
... In this context, water supply and sanitation systems consist of complex organized networks and facilities whose sustainability and efficiency are vital for the continuation of safe, acceptable, and affordable water and sanitation services for the end users (Romano et al. 2017). Given the importance of this topic, several studies have been conducted to better understand the features of water and sanitation infrastructure and evaluate its efficiency and sustainability from an engineering, environmental, and economic perspective (see for instance, Marques and Monteiro 2003;Makropoulos and Butler 2010;Xu et al. 2014;Li et al. 2015;Molinos-Senante et al. 2016a;Pérez et al. 2019;Salleh et al. 2019). ...
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Water leakage in the urban water cycle involves relevant economic, social, and environmental negative impacts. Thus, reducing water leakage is a key challenge for both water regulators and water companies. This study estimated the evolution (2007–2015) of the marginal cost of improving the quality of service in terms of water leakage in the Chilean water industry, which involves full private, concessionary, and public water companies. In water companies, management skills and efforts play an important role in meeting water leakage targets. Thus, this study employed a cost frontier model where it was assumed that unobserved management ability interacts with output and water leakage factors. The results reveal high levels of cost efficiency for the average water company. Management increases outputs and reduces water leakage and, thus, has a positive impact on costs and efficiency. The marginal cost of reducing water leakage is higher for the public water company than for private and concessionary water companies. The average estimated marginal cost of reducing water leakage was 0.349 €/m3, which means that a water company has to spend an extra 0.349 € in operating costs to avoid a cubic meter of water leakage. Some policy implications were discussed based on the results of this study.
... However, due to external contamination, decay of residual chlorine could occur, which could affect the tap water quality at the farthest end of the water distribution network. Water leakage and biofilm formation are the two leading sources of contamination in water distribution networks [6,7]. Therefore, it is important to ensure adequate residual chloride concentration in finished water to reduce the probability of microbial growth during distribution [8]. ...
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Several factors play a role in chlorine consumption in drinking water networks such as microbial contamination and dissolved organic matter (DOM). This study investigated the simultaneous impacts of seasonal variations on chlorine consumption and DOM composition for a year-long period in three different full scale water distribution networks in a southern city of China. Efforts were made to determine the association between different fluorescence moieties in DOM of finished water and chlorine consumption through excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC). The chlorine consumption was also found to be directly related to N-Nitrosodimethylamine (NDMA) and NDMA-formation potential (NDMA-FP), presenting consequence of excess residual chlorine. The wet season with high rainfall showed elevated consumption of chlorine on the opposite of dry season. During wet season, humic-like component in finished water was dominant than protein-like features and its abundance decreased in dry season. Results proved that chlorine consumption was season dependent and highly influenced by DOM composition in the finished water. Unlike the bulk quality parameters and protein-like component, fluorescence moieties related to humic substances acted as a surrogate for the chlorine consumption. Based on humic-like component, a single excitation based fluorescence peak, I245/410 or I335/410, was also extracted from EEMs of finished water samples and validated on different water distribution networks. These two single peaks well-explained the trends of residual chlorine and have the potential for on-line monitoring and portable purposes. This field-based study demonstrated application of fluorescence spectroscopy in designing chlorine dose to obtain optimal residual chlorine at consumer’s tap.
Water distribution networks (WDNs) are infrastructure systems that have high socioeconomic values, for which efficient operation and management are required to ensure minimal amount of waste which can be represented in the form of leaks. Leak detection is considered as one of the challenges faced by municipalities operating WDNs because it either involves shutting down the system or require using expensive equipment and technologies. In this paper, a novel noninvasive and nondestructive methodology for detecting leaks in water pipes was tested. Ground penetrating radar was used for accurate determination of pipe location, followed by infrared (IR) thermographic imaging for determining the leak location using four different operating conditions. Results were statistically analyzed using analysis of variance and pairwise comparison methods. Several factors were found to affect the accuracy of the proposed methodology in predicting the leak location, namely, the characteristics of the studied surface (i.e. emissivity), the characteristics of the surrounding environment (i.e. ambient temperature and relative humidity), and the operating conditions of the IR camera (i.e. speed and height of the camera). The results obtained in this study have also shown that under high ambient temperatures and high relative humidity conditions, a higher speed of the IR camera would reduce the impact of noise on the collected thermal contrast and therefore, would give better leak location prediction results. The tested methodology proved the flexibility of the approach and the ability of accurately predicting the leak locations under different conditions.
Thesis
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Leakage in drinkable water distribution systems have been causing significant water and energy losses, especially in developing countries. The leakage impacts over the systems performance are mainly addressed to the increase of pumped flows required to supply the usual demand and additional leakage flows. The extra flow implies in greater input energy, higher friction losses and a general unbalance of the system operational conditions, which cause inefficiency. In such a context, to address the increase of leakage in water networks it is necessary to understand its causes, characteristics and consequences. In this research an intensive experimental investigation was performed regarding leakage through round hole orifices in a laboratory pipe system. The focus of the experimental approach was developing relationships between the leakage characteristics, the system hydraulics and the system’s energy balance. Such a holistic experiment is rare in literature, specially because the leakage water losses traditionally draw the researchers attention to hydraulics, leaving aside impacts in efficiency and energy losses. Unexpectedly, the results show that the understanding about leakage hydraulics in water distribution systems still needs improvement, in order to better quantify leakage flows and develop reliable hydraulic models. The experiments with round orifice leaks pointed out that the required advances are mainly addressed to the leakage flow regime, which is usually adopted as a complete developed turbulent flow. Since this assumption was not necessarily verified in the experimental data analysis, better efforts are needed to understand the impacts of different leakage Reynolds numbers in leakage flows. Results regarding the leakage impacts in the system energy balance have shown that the increase of leakage have caused a greater inefficiency, which means that large amounts of energy were required to supply similar demand conditions in the presence of larger leakage flows. However, the analysis of individual components of systems energy losses (e.g. continuum head losses, local leakage head loss, hydraulic pump energy losses) points to different sensibility levels according to leakage conditions, which sometimes could even show better performance for higher leakage. It is important to note that the relationships developed in this research are binded to the laboratory system employed, but could guide further research in other systems.
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We analyze optimal investments, to reduce water losses, in a regulated water industry, with perfectly inelastic demand and private information about local investment efficiency. We compare the public and private ownership cases, both subject to the same regulatory (revenue cap) mechanism. The theoretical analysis is supported by a calibration and simulation exercise. The incentive to invest is affected by ownership, financial structure and revenue cap. Overinvestment results in private firms as the cost of capital is accounted differently. In public firms: (i) the effect of the revenue cap is diluted and investments distortions with respect to a benevolent social planner are negligible; (ii) information rents are valued according to the marginal cost of public funds; (iii) the distortionary taxation and a price inelastic demand drive local politicians to maximize water revenues to finance investments and to increase municipal fiscal gains. Price differences result from differences in ownership and financial structure.
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This paper presents a study of similarities between electrical and hydraulic pressurized networks. The primary objective is to examine whether or not it is possible to use electrical laboratory networks measuring voltage to study leak-region detection strategies measuring flow in water-distribution networks. In this paper, the strategy used to compare the networks is error-domain model falsification, a previously developed methodology for data interpretation that combines engineering knowledge with models and data to enhance decision making. Simulation results obtained for a part of the water-supply network from the city of Lausanne are compared with an analogous electric network. The electrical network is simulated using resistors to mimic the pipes. The consequence is that the electrical model is linear. The resistance values are obtained by computing the hydraulic resistance for each pipe, given by the Hazen-Williams equation. The compatibility of the two networks is evaluated through simulations in three ways: (1) comparing flow predictions obtained by simulating several leak scenarios; (2) comparing the expected identifiability (performance) of the two networks; and (3) comparing sensor placement configurations. The analyses show that even though the models have varying characteristics of underlying physical principles (the electrical model is linear while the hydraulic model is non-linear), the results are within generally accepted engineering limits of similarity (10%). This indicates that measurements on electrical laboratory networks have the potential to illustrate the efficiency and adaptability of leak-detection methodologies for full-scale water-supply and other pressurized hydraulic networks. Finally, two electrical laboratory physical networks, including an electrical model of part of the water network in Lausanne, were constructed and used in case studies to illustrate this adaptability.
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The Brazilian Labeling Program is a strong instrument for the conservation of energy. In addition to allowing consumers to evaluate the best products from an energetic point of view, it sets targets to make the products increasingly more efficient. In this context, buildings that can currently obtain the energy efficiency label are also inserted, demonstrating to customers the concern for sustainability. However, there are still many products and systems that can be labeled but for which legislation has not yet been enacted, including water supply systems. Owing to the different characteristics of the systems and the different possibilities for efficiency improvement, it is necessary to develop indicators that actually represent the reality of each system and make it possible to compare them. Thus, this study proposes the use of certain indicators for classification of the systems. A classification is also proposed by sector benchmarking in Brazil, presented as an example for the classification of Brazilian systems based on four indicators obtained by the SNIS.
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The detection and localization of leaks in water distribution networks (WDNs) is one of the major concerns of water utilities, due to the necessity of an efficient operation that satisfies the worldwide growing demand for water. There exists a wide range of methods, from equipment-based techniques that rely only on hardware devices to software-based methods that exploit models and algorithms as well. Model-based approaches provide an effective performance but rely on the availability of an hydraulic model of the WDN, while data-driven techniques only require measurements from the network operation but may produce less accurate results. This paper proposes two methodologies: a model-based approach that uses the hydraulic model of the network, as well as pressure and demand information; and a fully data-driven method based on graph interpolation and a new candidate selection criteria. Their complementary application was successfully applied to the Battle of the Leakage Detection and Isolation Methods (BattLeDIM) 2020 challenge, and the achieved results are presented in this paper to demonstrate the suitability of the methods.
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Leaking water from pipes depends on several factors such as pressure, pipe material, types of cracks and holes and also regime of flow through cracks. The effects of these factors on the leakage have been investigated by several researchers. However, few studies have been found considering the effects of soil around the pipes on the leakage discharge. Here, the leakage from polyethylene pipes is simulated in the laboratory, selecting several soils with different specifications. The leak discharge equation is adjusted to evaluate the effects of soil characteristics. Accordingly, grain diameter greater than 10% and 50% passing, coefficient of uniformity, coefficient of curvature, liquidity limit, plastic limit, plasticity index and hydraulic permeability have been considered to represent the soil properties. It is observed that the leakage is changed in accordance with most of the above parameters. The effects of grain diameter greater than 50% passing, plastic limit and hydraulic permeability are higher on the leakage, comparing to those of other parameters. However, no meaningful relationship is observed between the leakage and some parameters. The effects of significant characteristics are shown by the equations presented in this study.
Chapter
The water-energy nexus describes the connection between water and energy. Here we focus on energy for water supply to urban areas of China. Electricity use is one of the main costs for water companies and tends to be the main source of greenhouse gas emissions during water supply. In a country where reducing energy use and emissions is now an important part of the national agenda, managing energy use will become a major focus for the water industry. This chapter provides an overview of energy use at each stage of water supply in China: sourcing and transfer, water treatment, central distribution, and distribution within high-rise buildings. We then focus specifically on water distribution, which is a major energy user, and use statistical data from four cities in China and Japan to draw conclusions on how city layout affects the energy needed to supply water.
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Leak detection and localization in water distribution networks (WDNs) is of great significance for water utilities. This paper proposes a leak localization method that requires hydraulic measurements and structural information of the network. It is composed by an image encoding procedure and a recursive clustering/learning approach. Image encoding is carried out using Gramian angular field (GAF) on pressure measurements to obtain images for the learning phase (for all possible leak scenarios). The recursive clustering/learning approach divides the considered region of the network into two sets of nodes using graph agglomerative clustering (GAC) and trains a deep neural network (DNN) to discern the location of each leak between the two possible clusters, using each one of them as inputs to future iterations of the process. The achieved set of DNNs is hierarchically organized to generate a classification tree. Actual measurements from a leak event occurred in a real network are used to assess the approach, comparing its performance with another state-of-the-art technique, and demonstrating the capability of the method to regulate the area of localization depending on the depth of the route through the tree.
Chapter
Water distribution networks (WDNs) are vital infrastructure which serve as a means for public utilities to deliver potable water to consumers. Naturally, pipelines degrade over time, causing leakages and pipe bursts. Damaged pipelines allow water to leak through, incurring significant economic losses. Mitigating these losses are important, especially in areas with water scarcity, to allow consumers to have adequate water supply. Globally, as the population increases, there is a need to make water distribution efficient, due to the rising demand. Thus, leak detection is vital for reducing the system loss of the network and improving efficiency.
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The water distribution network (WDN) is critical in daily life because it provides treated water to consumers. However, WDN in Malaysia is facing a significant amount of water loss during the water distribution process (i.e., non-revenue water (NRW) with an average percentage of 35.6%. While one of the leading causes of NRW is old pipes, water operators are still facing barriers to rehabilitate old pipes to new pipes. Therefore, this study aims to identify the strategies to improve current practice in rehabilitating old pipes. To achieve that objective, open-ended individual interviews will be performed with sixteen individuals that have experience in managing WDN and NRW in Malaysia. This research contributes to identify the current practice/method, which has three main categories i.e. people, technology, and process in rehabilitating old pipes from industry practitioners’ perspectives, which could assist researchers and industry practitioners in developing strategies to reduce NRW among water operators. The findings of this research can help to improve WDN in reducing NRW.
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The need to conjunctively manage water and energy has found widespread acceptance by the scientific community and professionals. However, its implementation on the ground has been limited due to the lack of enough evidence-based studies, proof of concepts, and an actionable agenda. This study aims to plug this gap by conducting a systematic scientific study to evaluate water and energy savings in the water supply system managed by the Metropolitan Waterworks Authority (MWA) of Thailand. A hydraulic model using EPANET 2 was developed for the pilot area within the framework of water-energy nexus, to analyze water and energy consumption, and potential tradeoffs for several alternatives. The study found that decreasing the service pressure will conserve water, while increasing the supply pressure will conserve overall energy uses by the utility and the consumers. Further, the application of hydro turbines can reduce pressure and generate electricity, while Pressure Reducing Valve (PRV) can reduce leakage by 20-25% in case of high pressure. A supply pressure of 18 m with PRV can reduce the total energy use by 32% (from 0.6765 to 0.4613 kW h/m³). Study results help water utilities such as MWA in taking tangible decisions to enhance both water and energy security.
Chapter
Increased demand for water due to population growth, climate change, and growth in agriculture and industry is driving the need to use water resources more efficiently. There is also political pressure on water utilities to constrain price inflation on water bills while at the same time protecting the environment. Improving water efficiency reduces water scarcity and maximizes the benefits provided by existing water infrastructure. It also frees up water for other users, both human and natural.
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Health monitoring devices are critical for the safe and reliable operation of water supply systems, but their chemical batteries are easily depleted. Thus, this paper developed a micro-vertical axis water turbine that converts part of the water head into electrical energy and supplies power for the monitoring device. The performance of four groups of micro-turbines was investigated in detail through experimental testing. Different from our previous study, the entire performance curves of micro-turbines at different rotation speeds and flow velocities were obtained in order to consider the wide range of flow velocities inside the real water pipeline. The feasibility of the designed turbines in the power supply system was verified by on-site testing. The experimental results show that different types and opening sizes of blocks have a distinct influence on the output power of micro-turbines. Each type of block has the corresponding optimal opening size to gain the highest performance. Within a certain range, the maximum output power varies linearly with the increase in flow velocity. In a specific flow velocity, the optimal rotational speed of the micro-turbine generated the maximum output power can be predicted by the power curve. In addition, through the experimental data, it is found that among all the measured turbines, the 12-blade hollow shaft turbine with a 90% eye-shaped block is the best one, with an output power of 88.2 W and an efficiency of 15.76%. Finally, the results of an on-site test are consistent with that of the experiment properly, which verifies the reliability of the measured data in the laboratory.
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Water supply systems (WSS) in developing countries present high water loss and energy consumption rates, thus strategies for conservation of these resources are needed. The challenge is to define which strategies offer better results based on multiple criteria and on the different interests of the stakeholders involved. The objective of this study is to apply the decision support tool, named Water Supply Systems Management (WSSM), which uses the Analytic Hierarchy Process, to establish a hierarchy between the strategies. A case study was carried out in Curitiba, Brazil. Three strategies were selected: leak detection and correction, rational use of water, and the replacement of old water mains. These strategies were evaluated according to implementation cost, flow rate, energy consumption, and population coverage criteria. The leak detection and correction was ranked as the best option. The results of this study show this tool helps to devise guidelines for the efficient use of water and energy in the WSS.
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The use of controlled, small amplitude transient (water hammer) signals for the detection of leaks in pipeline systems is a promising area of research. A pressure transient travels along the system at high speed and is modified by the system during its travel. Leaks within a pipeline partially reflect these pressure signals and allow for the accurate location of a leak by tracing the reflection to its source – a technique commonly known as time domain reflectometry. This paper discusses and provides possible solutions to a number of practical issues associated with leak detection methods of this type, including the impact of the system configuration and methods for detecting leak reflected signals within a transient trace. A set of equations has been derived to locate leaks in a pipeline for all locations of the transient source and measurement stations, and is essential for an automated monitoring system that uses more than one simultaneous measurement of the transient signal. A change detection algorithm is used in this paper to provide an automated approach for detecting leak reflections, which can reduce the ambiguity associated with simple visual inspection of the transient trace. This procedure was validated by both operational and offline (pipeline shutdown) experimental tests conducted at the University of Adelaide
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Leaks in pipelines contribute to damping of transient events. That fact leads to a method to find location and magnitude of leaks. Because the problem of transient flow in pipes is nearly linear, the solution of the governing equations can be expressed in terms of a Fourier series. All Fourier components are damped uniformly by steady pipe friction, but each component is damped differently in the presence of a leak. Thus, overall leak induced damping can be divided into two parts. The magnitude of the damping indicates size of a leak whereas different damping ratios of the various Fourier components are used to find location of a leak. This method does not require rigorous determination and modeling of boundary conditions and transient behavior in the pipeline. The technique is successful in detecting, locating and quantifying a 0.1% size leak with respect to the crosssectional area of a pipeline.
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Fluid transients result in a substantial amount of data as pressure waves propagate throughout pipes. A new generation of leak detection and pipe roughness calibration techniques has arisen to exploit those data. Using the interactions of transient waves with leaks, the detection, location and quantification of leakage using a combination of transient analysis and inverse mathematics is possible using inverse transient analysis (ITA). This paper presents further development of ITA and experimental observations for leak detection in a laboratory pipeline. The effects of data and model error on ITA results have been explored including strategies to minimize their effects using model error compensation techniques and ITA implementation approaches. The shape of the transient is important for successful application of ITA. A rapid input transient (which may be of small magnitude) contains maximum system response information, thus improving the uniqueness and quality of the ITA solution. The effect of using head measurements as boundary conditions for ITA has been shown to significantly reduce sensitivity, making both detection and quantification problematic. Model parsimony is used to limit the number of unknown leak candidates in ITA, thus reducing the minimization problem complexity. Experimental observations in a laboratory pipeline confirm the analysis and illustrate successful detection and quantification of both single and multiple leaks.
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The water loss from a water distribution system is a serious problem for many cities, which incurs enormous economic and social loss. However, the economic and human resource costs to exactly locate the leakage are extraordinarily high. Thus, reliable and robust pipe failure models are demanded to assess a pipe's propensity to fail. Beijing City was selected as the case study area and the pipe failure data for 19 years (1987-2005) were analyzed. Three different kinds of methods were applied to build pipe failure models. First, a statistical model was built, which discovered that the ages of leakage pipes followed the Weibull distribution. Then, two other models were developed using genetic programming (GP) with different data pre-processing strategies. The three models were compared thereafter and the best model was applied to assess the criticality of all the pipe segments of the entire water supply network in Beijing City based on GIS data.
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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.
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Bayesian statistics offers an elegant and theoretically consistent approach for providing management advice under uncertainty. This is of particular importance for water utilities who are facing large scale capital expenditure due to the deterioration and rehabilitation of ageing infrastructure. Robust quantification of uncertainty is critical in ensuring efficient decision-making. Further, Bayesian statistics provides a way of formalising the process of learning from data to update prior beliefs. Again, this is particularly relevant for water utilities that commonly have incomplete or unreliable historical data sets and, as a consequence, rely heavily on engineering experience in making decisions. However, despite the appropriateness of Bayesian inference within the engineering field, it has yet to gain widespread acceptance and use within asset management. The objective of this paper is to provide an in-depth, yet practical, application of Bayesian statistics and its use within the context of asset management. We hope that this will increase the accessibility of such methods.
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A planning strategy is presented that aims at establishing the optimal replacement schedule for a water distribution network. Two performance indicators are defined. The first accounts for structural state (total cost defined as the sum of pipe replacement cost and the expected cost of pipe break repairs) and the second for hydraulic performance (minimization of the pressure deficit). A multiobjective objective function is defined based on these two indicators and a genetic algorithm optimization technique is used to identify optimal solutions (Pareto front). Three management strategies are considered to choose a replacement schedule among those making up the Pareto front: (1) a prostructural strategy that only considers the structural indicator; (2) a prohydraulic strategy that integrates both structural and hydraulic indicators; and (3) a budgetary constraint strategy which assumes a predefined budget for replacement expenditures. The proposed planning strategy was tested on two hypothetical networks. Synthetic pipe break records were generated using a statistical pipe break model. A Bayesian inference approach was then used to estimate parameters values from these pipe break series. A comparison of the different management strategies is provided as advantages of using Bayesian inference are discussed.
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A procedure is described that uses the history of main breaks to forecast how the number of breaks would change with time if the pipe were not replaced; a separate analysis predicts the failure rate of newly installed pipes. These forecasts are combined with cost data and a discount rate that accounts for inflation to determine the optimal replacement date.
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The cost of water main breaks can represent a significant portion of a distribution system's maintenance costs. Although qualitative guidance is available on why pipes break and when they should be replaced, there are no universal quantitative rules for when to replace pipe. This paper gives a simple method for determining which pipes need to be replaced, based on the history of recorded breaks.
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Water Sensitive Urban Design (WSUD) is a recent planning and design philosophy in Australia primarily used to minimise the hydrological impacts of urban development on the surrounding environment. As local governments plan and regulate the bulk of public and private infrastructure and development, they are key participants in the implementation of WSUD. However, according to research conducted involving 38 municipalities in Melbourne, Australia, the implementation of WSUD is inconsistent across the metropolitan area. The mixed methods research comprised a survey of municipal officers, interviews with the officers and mayors, and a review of municipal accountability documents. The results revealed a strong municipal commitment to WSUD in areas bounded by the coast or where the natural vegetation exceeds 50% of the municipal area. Furthermore, these committed municipalities tended to coincide with communities of higher wealth and population. Overall, the analysis revealed three types of municipalities – high, partial, and limited commitment – that are indicated by a variation in environmental values, demographic and socio-economic status, local organised environmentalism, municipal environmental messages, and intergovernmental disposition. This paper argues for policy reform for WSUD, as it is largely sympathetic to the highly committed municipalities, and highlights the need to enable the participation of publics in the municipalities of limited and partial commitment by linking WSUD to greater public concerns and building commitment through diverse policy interventions.