Table 1 - uploaded by Bryan W Karney
Content may be subject to copyright.
Source publication
Criteria which stipulate the minimum pressure at which water is to be delivered to customers from a water distribution system (WDS) differ around the world. Thus, interestingly, the pressure delivered to a customer might be judged high enough to meet standards in some countries, while water delivered under the same pressure in other countries is co...
Context in source publication
Similar publications
Over the past few decades, various evolutionary algorithms (EAs) have been applied to the optimization design of water distribution systems (WDSs). An important research area is to compare the performance of these EAs, thereby offering guidance for the selection of the appropriate EAs for practical implementations. Such comparisons are mainly based...
Water distribution system design is a challenging optimisation problem with a high number of search dimensions and constraints. In this way, Evolutionary Algorithms (EAs) have been widely applied to optimise WDS to minimise cost subject whilst meeting pressure constraints. This paper proposes a new hybrid evolutionary framework that consists of thr...
This paper examines the feasibility of pipe diameter reduction in a pumped water distribution system (WDS) during depopulation from the viewpoint of life cycle cost (LCC). A pipe replacement planning model using a genetic algorithm (GA) was developed and applied to a pumped and branched WDS under depopulation. Moreover, a local search algorithm (LS...
Sub-standard residual water pressures in urban water distribution systems (WDS) are a prevalent phenomenon in developing countries – South Africa being no exception. The phenomenon of sub-standard pressure is poorly understood, with intermittent supply ultimately resulting when there is no residual pressure left in the system. This research address...
Water Distribution Systems (WDSs) are among the most important infrastructures that are critical for the smooth functioning of communities. However, age-old existing WDSs are progressively at risk in the United States. Since failure in a WDS may affect other interdependent infrastructure and result in high economic consequences, water utilities are...
Citations
... Since the demands of various categories of end-users are not exactly the same, their specifics should be critically considered during the design process. Most often, inability of water distribution systems to meet demand at an efficient pressure is often caused by inappropriate pipe sizing [5], failure to take into account real-time water consumption patterns of the target community in terms of population, and spikes in demand at certain periods of the day. Other issues are leaks and interruptions caused by pipe bursts. ...
In this work, the EPANET software is used to parametrize the design, simulate and optimise the overall cost of building and running a reliable, sustainable and efficient communal Water Supply System. Considering a model community of forty houses with an average of six occupants per home, the developed optimization algorithm using the simulated annealing heuristics approach minimizes the total cost of continuous water distribution to the community through a system of pipe network in a way that satisfies the critical hydraulic rules and constraints for efficient water distribution. Thus, the controlled variables of the simulated system include volumetric flow, velocity and head loss. To realize the desired goal, the prototyped communal water distribution system was first simulated by water free fall i.e., only gravity feed under a peak demand flow condition. This facilitated the identification and localization of head-loss zones. Subsequently, virtual pump stations of various capacities were optimally introduced as boosters at identified nodal points to overcome critical head losses. The response of the system to varying capacities of the booster pumps was then used to analyse and determine the optimum capacity of the pump. Simulation outcome showed that the optimum least cost design for a sixtyyear system’s life cycle is achieved by using a combination of gravity and 5 hp (3.73 kW) pump with optimum pipe diameter ranging from 60 - 150mm.
... The sizes of pipes are taken as the decision variables of the optimisation problem. In this problem, a minimum allowable pressure head of 28 meters of water is set to be satisfied at all times (Ghorbanian et al., 2015). The variable speed pump handles the pressure head constraint, as discussed in Appendix B. ...
... Meanwhile, the pressure head after the PRV is expressed as the PRV setting in EPANET, and the pump head provided could be calculated as the pressure difference before and after the PRV. The PRV setting is adjusted to ensure the pressure head of the critical demand node (node with minimum pressure head in the network) always remains to be equal and higher than the minimum allowable head of 28 m of water (Ghorbanian et al., 2015). The pump head at each simulation time-step could be calculated using the following equations: ...
... Optimum water pressure The optimum value of pressure is selected on the basis of source capacity, as well as volume of water supplied. Pressure in pipes is kept between minimum and maximum standards for "safe, reliable, and economic operation" [37,38]. ...
The challenge of achieving and measuring urban water sustainability is hard because of its complex nature. The sustainability of urban drinking water system (UDWS) is no exception, as integration of technical, environmental, social, economic, and institutional elements of sustainability is defying and perplexing in terms of its application and evaluation. This paper deals with the technical aspects related to the design, construction, operation, and maintenance factors of a UDWS. Measurement of the status of such factors is almost impossible in generic formats. Therefore, a list of measurable sub factors was developed through an extensive literature survey and refined by involving appropriate stakeholders. This led to the development of a hierarchy from criteria to factors and from factors to sub factors, making a case for the utilization of an analytic hierarchy process (AHP) for multicriteria analysis (MCA). Appropriate stakeholders were included in this research to address the issues for which there were major gaps in the literature. A set of guidelines were developed for the evaluation of the status of various sub factors in a quantitative format. It is concluded that a trans disciplinary framework, the involvement of stakeholders, and guidelines for adopting appropriate processes and techniques may improve the sustainability of stressed urban water systems.
... This test case has a high number of parameters and involves a simulation code for a realistically non-linear system. For reliability analysis, we will consider a simple problem of pipe breaks, which can be caused by too high pressures in the system [59]. This means that the pressure in the pipes should be reliably lower than some maximum permissible pressure. ...
In this paper, a fully decoupled simulation method is proposed for reliability-based design optimization (RBDO) based on thermodynamic integration and parallel tempering (TIPT). We show that the failure probability function and its gradient can be obtained simultaneously with once generalized reliability analysis, and thus the RBDO problem is converted to the traditional optimization problem efficiently. Firstly, the design parameters are deemed as uniformly distributed random variables, and an auxiliary probability density function (PDF) of random design variables is constructed to cover its whole parameter space. Then, based on thermodynamic integration, the estimation of failure probability is converted to a series of simple integration problems with smooth integrand, and they are estimated by running multiple Markov chains using the so-called parallel tempering method. Finally, importance sampling (IS) is used to estimate the failure probability function and its gradient, and the IS samples are obtained by resampling from the existing Markov chains without extra computation. The proposed method is tested with severa benchmarks, and the results show that it provides robust solution for problems with various nonlinear constraints compared to other popular methods, include double-loop Monte Carlo simulation (MCS), Quantile MCS, sequential optimization and reliability assessment, performance measure approach and reliability index approach.
... The existence of excessive pressure can significantly exacerbate the flow rate from active leaks. Moreover, high pressures during low-demand periods may cause more frequent pipe bursts and leaks (Thornton and Lambert 2007;AWWA 2016;Ghorbanian et al., 2015). Therefore, controlling pressure in WDNs is a concern and challenging task for water utilities worldwide. ...
... Furthermore, it has been widely recognized that PM yields a decrease in the frequency of pipe breaks (Lambert 2001; Lambert 2005, 2007;Girard and Stewart 2007;Lambert et al. 2013;Ghorbanian et al., 2015;Martínez-Codina et al., 2016). ...
Pressure management (PM) is commonly used in water distribution networks (WDNs) to provide a wide range of the benefits. This study presents an economic feasibility framework to support the decision-making process relating to the implementation of different PM schemes. In detail, the methodology allows for the assessment of the number of principal direct and indirect benefits and costs associated using pressure-reducing valves (PRVs). The methodology is applied to a district metered area in a WDN in Mashhad, Iran, by changing the existing fixed-setting to time-based (TM-PRV) and flow-based modulation (FM-PRV). The results indicate that FM-PRV is the most beneficial scheme for the studied case. The importance of the estimation of direct and indirect benefits is highlighted. The presented methodology is essential to persuade decision-makers in water utilities to recognize the significant benefits that can be achieved by implementing PM schemes to justify the investment decisions.
... Unfortunately, to date, PM optimization methods did not consider water age as a parameter or a restriction during the DMAs' optimization or WDN's hydraulic simulation process. To date, only a few studies dealt with the water aging factor in a WDN [23][24][25][26][27][28][29][30][31][32][33][34]. There are not though any thorough analyses combining the water aging and the chlorination rates. ...
... There are not though any thorough analyses combining the water aging and the chlorination rates. Previous studies have considered the correlation of pressure and water age [32,33], but none have extensively studied the possible impacts of PM measures implemented on the water age (WA). The current study, utilizing the existing calibrated hydraulic simulation model of Kos town WDN [35,36], tests already developed PM scenarios [6,13,34] introducing as optimization factors (and constraints) both the water age and the residual chlorine [37]. ...
In this paper, the effects of pressure regulation in a water distribution network (WDN)are being examined. Quality is hammered the most when pressure is reduced in a WDN and this occurs due to the increase of the age of water flowing inside the network pipes (water age is actually the total time the water remains inside the pipes before reaching the customer’s tap). Kos town WDN is used as the case study network. Kos town is the capital of the homonymous Greek island, among the most famous and popular Greek islands. The specific WDN is quite typical but very interested as it is extended along the seafront. The network’s hydraulic simulation model was developed through the WaterCad V8i software. As Kos experiences too high-water demand peaks and lows during summer and winter time respectively, its WDN has already been thoroughly studied, in order to regulate the pressure and reduce its annual water losses rates. Nevertheless, these scenarios have never been examined regarding the impact on the water quality. In the current study, the division of the WDN in DMAs and the use of a Pressure Reducing Valve (PRV) in the entering node of each DMA are being evaluated in terms of water age. Additionally, a swift optimization process takes place to produce different DMAs’ borders, based on the criteria of minimum nodal water age, instead of optimal pressure. Different scenarios were tested on the calibrated and validated hydraulic model of Kos town WDN.
... The tied relationship between water losses and operational pressure in WDNs has been proven in different research activities (e.g. Ghorbanian et al. (2015), Walski et al. (2006)). Lambert et al. (2013) addressed the modelling of leakage and pressure management. ...
This paper presents a project aimed at the optimization of a water distribution network located in Trento (Italy). Several in-depth hydraulic studies have been conducted in order to perform hardware modifications through sectorization procedures. Advanced Process Control methods have been designed in order to optimally and automatically manage the net pressure and the scheduling of the involved pumping stations. Net pressure has been minimized through two-layer Model Predictive Control techniques, while advanced logics have been designed for the pumps scheduling. The developed Advanced Process Control system has been successfully installed on the considered network and the achieved results are here illustrated.
... Water Resources Research heat wave, substantially increased UWD in water supply systems, especially those with low minimum service pressure criteria, can lead to unwanted consequences such as pipe failure, the inability to meet water demands at a suitable level of service (e.g., pressure), and water quality issues (Ghorbanian et al., 2015)-which ultimately may leave vulnerable residents without a sufficient amount of safe drinking water. Interestingly, the study of the impacts of heat waves on UWD is a research topic that has received very little attention in the literature , Hatvani-Kovacs, Belusko, Skinner, et al., 2016. ...
In water resources applications (e.g., streamflow, rainfall-runoff, urban water demand [UWD], etc.), ensemble member selection and ensemble member weighting are two difficult yet important tasks in the development of ensemble forecasting systems. We propose and test a stochastic data-driven ensemble forecasting framework that uses archived deterministic forecasts as input and results in probabilistic water resources forecasts. In addition to input data and (ensemble) model output uncertainty, the proposed approach integrates both ensemble member selection and weighting uncertainties, using input variable selection and data-driven methods, respectively. Therefore, it does not require one to perform ensemble member selection and weighting separately. We applied the proposed forecasting framework to a previous real-world case study in Montreal, Canada, to forecast daily UWD at multiple lead times. Using wavelet-based forecasts as input data, we develop the Ensemble Wavelet-Stochastic Data-Driven Forecasting Framework, the first multiwavelet ensemble stochastic forecasting framework that produces probabilistic forecasts. For the considered case study, several variants of Ensemble Wavelet-Stochastic Data-Driven Forecasting Framework, produced using different input variable selection methods (partial correlation input selection and Edgeworth Approximations-based conditional mutual information) and data-driven models (multiple linear regression, extreme learning machines, and second-order Volterra series models), are shown to outperform wavelet- and nonwavelet-based benchmarks, especially during a heat wave (first time studied in the UWD forecasting literature).
... To achieve reasonable operating conditions, different local standards for water pressures are set. For example, the MPC is 14 m in most Canadian provinces whereas it is 20 and 10 m in Australia and the United Kingdom, respectively (Ghorbanian et al. 2015). There are no universally acceptable or established rules or guidelines for specifying MPCs (Ghorbanian et al. 2015). ...
... For example, the MPC is 14 m in most Canadian provinces whereas it is 20 and 10 m in Australia and the United Kingdom, respectively (Ghorbanian et al. 2015). There are no universally acceptable or established rules or guidelines for specifying MPCs (Ghorbanian et al. 2015). Thus, there may be the possibility of revising the MPC for some WDSs. ...
Presented in this paper is a field data–based probabilistic approach to quantifying the expected pipe break rates of water distribution systems. Uncertain demands and variations in the roughness of pipes during their service lives are described as random variables. Sample values of these random variables are generated and input to a distribution system model to determine the resulting minimum and maximum pressures in Monte Carlo simulations. Based on an estimated break rate–maximum pressure relationship, the sample maximum pressures obtained from a Monte Carlo simulation are transformed into a sample of break rates, and the expected pipe break rate can subsequently be determined. The sample minimum pressures are used to gain a better understanding of the distribution network. This probabilistic approach is used for a part of the City of Hamilton’s network in Ontario, Canada. The results show that the frequency of low-pressure events is very small, but a higher minimum pressure criterion would inevitably increase expected pipe break rates. Local field data collection is necessary to use the proposed methodology. Savings resulting from reduced pipe break rates justify costs associated with data collection.
... Low-pressure conditions can cause customer dissatisfaction (e.g., unpleasant showering; malfunctioning dishwashers, clothes washers, and boilers). System energy is clearly wasted if water pressures are greater than required (Ghorbanian et al. 2015a).Yet a certain minimum pressure for appliance operations clearly should be supplied. ...
Pressure standards assist in the design of water distribution systems and the assessment of their performance. Although exact thresholds are sometimes rather vague, unusually high and low pressures are widely understood to increase costs and put systems at risk from events like pipe bursts at the high-pressure end to the risk of contaminant intrusion or poor firefighting conditions at the low-pressure end. Interestingly, because the definition of what conditions constitute acceptable pressures differs around the world, a delivery pressure might be considered acceptable in some regions and unacceptable in others. But if a wider range of system conditions is considered, including transient events, an interesting question arises as to what exactly the standards might mean and how violations should be evaluated. Specifically, what kinds of pressure transgressions are most crucial to system performance and economics and what kinds are merely inconvenient? Certainly the issue of evaluating consequences is relevant, but it is also complex because some consequences are not easily attributed to specific system conditions. As this paper considers, the frequency, duration, and intensity of the pressure violation are all relevant, but so is the vulnerability of the system to those violations. Few of these issues have yet received adequate attention, but it is to raising such a discussion that this paper is aimed. There is no doubt that pressure standards can help to assess system performance and to trigger system evolution (i.e., operational and capital investments). But if the criteria themselves, and the means to evaluate them, are too vague, so will be the corrective outcomes.
