Leakage In Water Distribution Systems Research Articles

Estimation method of natural rate of rise of leakage in water distribution system

Estimation method of natural rate of rise of leakage in water distribution system

Time-Series-Based Leakage Detection Using Multiple Pressure Sensors in Water Distribution Systems.

Leak detection is nowadays an important task for water utilities as leakages in water distribution systems (WDS) increase economic costs significantly and create water resource shortages. Monitoring data such as pressure and flow rate of WDS fluctuate with time. Diagnosis based on time series monitoring data is thought to be more convincing than one-time point data. In this paper, a threshold selection method for the correlation coefficient based on time series data is proposed based on leak scenario falsification, to explore the advantages of data interpretation based on time series for leak detection. The approach utilizes temporal varying correlation between data from multiple pressure sensors, updates the threshold values over time, and scans multiple times for a scanning time window. The effect of scanning time window length on threshold selection is also tested. The performance of the proposed method is tested on a real, full-scale water distribution network using synthetic data, considering the uncertainty of demand and leak flow rates, sensor noise, and so forth. The case study shows that the scanning time window length of 3–6 achieves better performance; the potential of the method for leak detection performance improvement is confirmed, though affected by many factors such as modeling and measurement uncertainties.

Optimal Selection and Monitoring of Nodes Aimed at Supporting Leakages Identification in WDS

Many efforts have been made in recent decades to formulate strategies for improving the efficiency of water distribution systems (WDS), led by the socio-demographic evolution of modern society and the climate change scenario. The improvement of WDS management is a complex task that can be addressed by providing services to maximize revenues while ensuring that the quality standards required by national and international regulations are upheld. These two objectives can be fulfilled by utilizing optimized techniques for the operational and maintenance strategies of WDS. This paper proposes a methodology for assisting engineers in identifying water leakages in WDS, thus providing an effective procedure for ensuring high level hydraulic network functionality. The proposed approach is based on an inverse analysis of measured flow rates and pressure data, and consists of three steps: The analysis of measurements to select the most suitable period for leakage identification, the localization of the best measurement points based on a correlation analysis, and leakage identification with a hybrid optimization that combines the exploration capability of the differential evolution algorithm with the rapid convergence of particle swarm optimization. The proposed procedure is validated on a reference hydraulic network, known as the Apulian network.

Localization of Emerging Leakages in Water Distribution Systems: A Complex Networks Approach

Localization of Emerging Leakages in Water Distribution Systems: A Complex Networks Approach

Pressure Zoning Approach for Leak Detection in Water Distribution Systems Based on a Multi Objective Ant Colony Optimization

Leakages result in considerable loss of water in water pipe networks. Therefore it is an important issue to detect leakage amount and its approximate location. Leakages in water distribution system are directly related to the operating pressure. In the current study, a new model is proposed for leakage amount and location detection and it is applied into two benchmark water distribution networks. In the proposed method, the water distribution networks are divided into three pressure zones in order to consider the leakage differences in different operating pressures. Then, nodal pressures and demands are calibrated using a new multi objective ant colony based optimization model. In this method, leaks are simulated as extra nodal demands. For determining the nodes where leakage happens, a probability based scheme is used. The leakage occurrence probability varies depending on the pressure zone that each node is located. The results illustrate the applicability of the proposed model for detecting the leakages in water distribution systems.

Assessment of future water availability under climate change, considering scenarios for population growth and ageing infrastructure

AbstractClimate change is likely to cause higher temperatures and alterations in precipitation patterns, with potential impacts on water resources. One important issue in this respect is inflow to drinking water reservoirs. Moreover, deteriorating infrastructures cause leakage in water distribution systems and urbanization augments water demand in cities. In this paper, a framework for assessing the combined impacts of multiple trends on water availability is proposed. The approach is focused on treating uncertainty in local climate projections in order to be of practical use to water suppliers and decision makers. An index for water availability (WAI) is introduced to quantify impacts of climate change, population growth, and ageing infrastructure, as well as the effects of implementing counteractive measures, and has been applied to the city of Bergen, Norway. Results of the study emphasize the importance of considering a range of climate scenarios due to the wide spread in global projections. For the specific case of Bergen, substantial alterations in the hydrological cycle were projected, leading to stronger seasonal variations and a more unpredictable water availability. By sensitivity analysis of the WAI, it was demonstrated how two adaptive measures, increased storage capacity and leakage reduction, can help counteract the impacts of climate change.

Survival Analysis of US Water Service Lines Utilizing a Nationwide Failure Data Set

Research into leakage in water distribution systems in the United States has shown that substantial amounts of real water loss can occur in service lines. The current research therefore sought to, first, describe trends in US service line failures on the basis of nearly 10 years of national‐level historical failure data; second, develop a structured survival analysis for various service line materials that have failed; and third, provide evidence to demonstrate to water industry stakeholders the importance of proactive water service line maintenance practices and strategies. Given that the condition of the existing water infrastructure in the United States continues to deteriorate, it is essential to ensure that service lines on private property be diligently maintained. This research on service lines will help shape safer design criteria, not only within individual residences, but also to support dependable maintenance procedures within water distribution systems.

Pressure control for minimizing leakage in water distribution systems

In the last decades water resources availability has been a major issue on the international agenda. In a situation of worsening scarcity of water resources and the rapidly increasing of water demands, the state of water losses management is part of man’s survival on earth. Leakage in water supply networks makes up a significant amount, sometimes more than 70% of the total water losses. The best practices suggest that pressure management is one of the most effective way to reduce the amount of leakage in a water distribution system. The approach presented in this study is aimed at modeling leakage as a function of pressure and pipe length, calibrating leakage coefficient, using fixed pressure reducing valves (PRVs) to develop pressure fluctuation and developing WaterCAD scenarios to minimize leakage through the most effective settings of PRVs. This approach was applied on a district metered area (DMA) in Alexandria, Egypt. The application of this approach produced some encouraging results, where the leakage through DMA was dropped by 37% for the best scenario. Thus, this approach is recommended as a decision support tool for determining a desirable solution for leakage reduction.

Optimization techniques for leakage management in urban water distribution networks

Abstract Reduction of leakages in water distribution systems (WDSs) is one of the major concerns for water industries. This paper presents a leakage reduction technique using pressure management by optimizing the water level in storage tanks, along with optimized control and localization of pressure-reducing valves (PRVs) in WDSs. A new mathematical tank and pump simulation algorithm is presented for controlling pressure in WDSs, by optimizing the water storage level in the tank depending upon the demand variations. The tank is used as a decision variable for the leakage reduction model. A modified reference pressure algorithm is introduced for improving PRV localization. A multiobjective genetic algorithm (NSGA-II) is used to find the optimized operational control setting of the PRV for leakage minimization. The proposed algorithm leads to a leakage reduction of 26.51% in Anytown WDS and 20.81% in a modified benchmark WDS. This technique leads to an appreciable reduction in leakage rate, with fewer PRVs required, taking into account constraints such as maintaining a lower hydraulic failure index (<0.01), emergency storage, etc. It can be concluded that the proposed novel leakage reduction technique provides a more cost effective and efficient solution for leakage control.

Intrinsic relationship between energy consumption, pressure, and leakage in water distribution systems

The basic implications of changes in delivery pressure on system energy use and cost, on leakage, excess pressure, and environmental impacts are explored. An analytical expression is first developed to characterize the primary relationships between energy use, leakage and pressure for a simple pipe segment. Then, two more realistic case studies, based on varying versions of the Anytown network, are considered. The results indicate that energy use responds more to changes in the delivery pressure in systems with higher leakage rates while reductions in pressures curtail energy use and leakage more dramatically in low resistance systems. Perhaps more surprisingly, systems with more effective water storage and thus uniform pressures tend to have higher leakage rates, greater energy usage, and higher GHG emissions relative to systems relying on direct pumping. The generalization that results from these studies is perhaps predictable but has profound implications: the higher the delivery pressure the greater will likely be the amount of water wasted and energy dissipated.

Estimating the environmental and resource costs of leakage in water distribution systems: A shadow price approach

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.

Leak Prediction Model for Water Distribution Networks Created Using a Bayesian Network Learning Approach

Water leakage in water distribution systems (WDSs) can bring various negative economic, environmental, and safety effects. Therefore, predicting water leakage is one of the most crucial tasks in water resource management; however, it is also one of the most challenging ones. Previous leakage-related studies have only focused on detecting existing leaks. This paper presents a novel model using expert structural expectation–maximisation, for predicting water leakage in WDSs. The model can take into account the uncertainty of leakage-related factors and balance the contribution of monitoring data and prior information in a Bayesian learning process to maximise leakage prediction accuracy. Moreover, the proposed method can indicate the most crucial factors affecting water leakage. The results of this study could benefit water utilities by aiding them in establishing an effective leakage control plan to minimise the risk of water leakage. A case study is presented to demonstrate the robustness and effectiveness of the proposed method.

Experimental Evidence of Leaks in Elastic Pipes

Several studies have been carried out in recent decades to establish a relationship between total head and leaks. In literature, the leakage governing equations have been analysed in light of pipe materials, water head, leak dimension or shape. Most of these contributions questioned the classical Torricelli equation, demonstrating through experimental evidence that the classical orifice law can give unsatisfactory results. Nevertheless, starting from the Torricelli equation, other exponential or linear governing equations have been proposed as mathematical models able to reproduce the leakages in water distribution systems (WDSs). To investigate the validity of the proposed governing equations, an experimental campaign was carried out by means of a water distribution network composed of approximately 500 m of polyethylene pipes. The experiments were designed to investigate the effects of leak area and pipe rigidity on discharge. Furthermore, the effect of leak size enlargement with water head was analysed. Finally, the proposed research contributes to the population of a database for estimating the coefficients of head-discharge relationships.

A review of methods for burst/leakage detection and location in water distribution systems

The problem of bursts and leakages in water distribution systems has received significantly increased attention over the past two decades. As they represent both an environmental and an economical issue, how to reduce water loss through bursts and leakages is a challenging task for water utilities. Consequently, various techniques have been developed to detect the location and size of leakages. The methods for bursts (or leaks) detection and location can be broadly divided into two main categories, one based on hardware and the other based on software. Hardware-based methods include (i) acoustic detection methods such as listening rods, leak correlators, leak noise loggers and (ii) non-acoustic detection methods such as gas injection, ground penetrating radar technology and infrared photography. Software-based methods make use of the data collected by real-time pressure and/or flow sensors and several artificial intelligence techniques and statistical data analysis tools, including (i) methods based on numerical modeling methods, such as inverse transient analysis, time domain analysis and frequency domain analysis, and (ii) some non-numerical modeling methods, such as artificial neural networks, Bayesian inference systems, the Golden section method, and Kalman filtering. In this article, the authors describe the methods for pipe network burst location and detection, summarize the features of each method, and propose a suggestion for future work.

Knowledge-Based Optimization Model for Control Valve Locations in Water Distribution Networks

This paper presents a knowledge-based optimization model for minimizing leakage in water distribution systems through the most effective location and setting of control valves. The optimization model is based on the use of a genetic algorithm (GA), which is known for its robustness for handling the optimization of water distributions networks. Knowledge of the water distribution system has been incorporated into the optimization model to reduce the search space and to enhance the model efficiency in finding the optimal solutions. A single optimization model to search for both the optimal location of valves and their settings has been used. These two improvements over other models have enhanced the efficiency of the model and improved the search for the optimum solution. The model has been used to test leakage minimization in a benchmark water network studied by other researchers and has proven to be very efficient and robust.

Experimental Setup to Examine Leakage Outflow in a Scaled Water Distribution Network

Abstract Leakages in water distribution systems are one of the most emerging topics in the field of water supply. Therefore, understanding leak hydraulics is of high interest. This paper outlines an experimental laboratory network. The main purpose of this experimental water distribution system is to gain knowledge and experience for two tasks. First, the verification of the hydraulic modeling approaches concerning leakage outflow. Second, the practically performance evaluation of algorithms for leakage localization developed at our institute. The chosen laboratory setup allows multiple leakages, flow measurements at every position as well as pressure measurements on defined locations.

GPR-Based Water Leak Models in Water Distribution Systems

This paper addresses the problem of leakage in water distribution systems through the use of ground penetrating radar (GPR) as a nondestructive method. Laboratory tests are performed to extract features of water leakage from the obtained GPR images. Moreover, a test in a real-world urban system under real conditions is performed. Feature extraction is performed by interpreting GPR images with the support of a pre-processing methodology based on an appropriate combination of statistical methods and multi-agent systems. The results of these tests are presented, interpreted, analyzed and discussed in this paper.

적응 칼만필터를 이용한 상수관망의 누수감시 기법

수돗물의 공급과정에서 발생되는 상수관망의 누수는 소중한 수자원의 손실, 공급에너지의 추가적인 소요 등 사회경제적인 손실을 초래한다. 본 연구에서는 관로 상에 설치되어 실시간으로 계측되는 유량자료를 이용하여 누수를 감시하는 모형을 적응 칼만필터 기법을 이용하여 제시하였다. 제안된 누수감시 알고리즘에서는 수돗물 사용량의 시간적 변화와 요일적 변동을 고려함으로써 예측의 신뢰도를 향상시키는 방안을 제시하였다. 또한 기존의 칼만필터 기법에 혁신과정을 추가하여 잡음의 공분산에 대한 자동보정을 통하여 예측의 정확도를 개선하였다. 개발된 모형은 사인형태의 가상 유량자료에 대한 모의실험을 통하여 적응 칼만필터 기법의 예측정확도를 기존의 칼만필터 기법과 비교하였으며, JE시의 2개소 블록유량자료에 대한 현장 적용성 평가를 실시하였다. 본 연구의 결과는 관로의 파열에 의한 누수 및 비정상적인 용수사용량에 대한 감시를 통하여 상수관망의 효율적인 운영관리에 적용될 수 있을 것으로 기대된다. Leakage in water distribution system causes social and economic losses by direct water loss into the ground, and additional energy demand for water supply. This research suggests a leak detection model of using adaptive Kalman filtering on real-time data of pipe flow. The proposed model takes into account hourly and daily variations of water demand. In addition, the model's prediction accuracy is improved by automatically calibrating the covariance of noise through innovation sequence. The adaptive Kalman filtering shows more accurate result than the existing Kalman method for virtual sine flow data. Then, the model is applied to data from two real district metered area in JE city. It is expected that the proposed model can be an effective tool for operating water supply system through detecting burst leakage and abnormal water usage.

Numerical approximation of an optimization problem to reduce leakage in water distribution systems

Leakage represents a large part of the supplied water in Water Distribution Systems (WDS). Consequently, it is important to develop some efficient strategies to manage such a phenomenon. In this paper an improved formulation of the hydraulic network equations that incorporate pressure-dependent leakage, is presented and validated. The formulation is derived from the Navier-Stokes equations and solved using an adequate splitting method. Then, this formulation is used to study a constrained optimization problem with the objective to minimize the distributed water volume reducing the leakage. The problem is described and validated for academic case studies and real networks.

Leakage detection and location in water distribution systems using a fuzzy-based methodology

Loss of water due to leakage is a common phenomenon observed practically in all water distribution systems (WDS). However, the leakage volume can be reduced significantly if the occurrence of leakage is detected within minimal time after its occurrence. This paper proposes a novel methodology to detect and diagnose leakage in WDS. In the proposed methodology, a fuzzy-based algorithm has been employed that incorporates various uncertainties into different WDS parameters such as roughness, nodal demands, and water reservoir levels. Monitored pressure in different nodes and flow in different pipes have been used to estimate the degree of membership of leakage and its severity in terms of index of leakage propensity (ILP). Based on the degrees of leakage memberships and the ILPs, the location of the nearest leaky node or leaky pipe has been identified. To demonstrate the effectiveness of the proposed methodology, a small distribution network was investigated which showed very encouraging results. The proposed methodology has a significant potential to help water utility managers to detect and locate leakage in WDS within a minimal time after its occurrence and can help to prioritise leakage management strategies.