Stochastic approach for performance evaluation regarding water distribution systems

2007 ◽  
Vol 56 (9) ◽  
pp. 29-36 ◽  
Author(s):  
M. Möderl ◽  
T. Fetz ◽  
W. Rauch
Keyword(s):  
Performance Evaluation ◽  
Case Studies ◽  
Distribution Systems ◽  
Water Distribution ◽  
Performance Indicator ◽  
Water Distribution Systems ◽  
Stochastic Approach ◽  
Cumulative Distribution ◽  
Design System ◽  
The Impact

A traditional procedure for performance evaluation of systems is to test approaches on one or more case studies. However, it is well known that the investigation of real case studies is a tedious task. Moreover, due to the limited amount of case studies available it is not certain that all aspects of a problem can be covered in such procedure. With increasing computer power an alternative methodology has emerged, that is the investigation of a multitude of virtual case studies by means of a stochastic consideration of the overall performance. Within the frame of this approach we develop here a modular design system (MDS) for water distribution systems (WDSs). With the algorithmic application of such a MDS it is possible to create a variety of different WDSs. As an example of stochastic performance evaluation the impact of pipe breakages on WDSs is estimated applying a pressure driven performance indicator. This performance indicator is evaluated stochastically. Likewise the performance evaluation of a variety of WDSs is also performed stochastically. Cumulative distribution function, histogram and other statistical properties of 2,280×1,000 performance results of the different WDSs are calculated to highlight the applicability of the introduced stochastic approach.

scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

Graph-based approach for generating virtual water distribution systems in the software VIBe

2010 ◽  
Vol 10 (6) ◽  
pp. 923-932 ◽  
Author(s):  
R. Sitzenfrei ◽  
M. Möderl ◽  
W. Rauch
Keyword(s):  
Case Studies ◽  
Real World ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Virtual Water ◽  
Systematic Investigation ◽  
Quality Performance ◽  
Virtual Infrastructure ◽  
Spatially Distributed

Application of virtual case studies (VCS) is a well established technique in environmental engineering to test measures, approaches, models or software. However, preparation of VCS for an infrastructure network is a tedious task. In literature, approaches can be found which generate very simplified VCS, which are only partly comparable with real world case studies. VCS which are more comparable with real world case studies can be generated with the software VIBe (Virtual Infrastructure Benchmarking). With VIBe, a methodology for algorithmic generation of VCS with varying spatially distributed boundary conditions was presented. Therein the investigated infrastructure is constructed accordingly to the state-of-the-art design rules meeting the requirements of the generated virtual urban environment. In this paper the module for the generation of water distribution systems (WDS) is presented. The generated WDS are set in context with data from real world WDS and systematically investigated. A set of 75,000 virtual WDS with varying properties is characterized and stochastically analysed in order to identify system coherences e.g. impact of mesh degree on hydraulic, water quality performance and costs. An example involving the systematic investigation of a simple pipe sizing algorithm with the set of 75,000 WDS is shown.

scholarly journals Average Operating Pressure Effect on Water Supply Systems Performances. A Case Study for 12 Romanian Small Water Distribution Networks

2021 ◽  
Vol 11 (2) ◽  
pp. 143-150
Author(s):  
E. Vitan ◽  
Anca Hotupan ◽  
Adriana Hadarean
Keyword(s):  
Performance Evaluation ◽  
Water Loss ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Distribution Networks ◽  
Water Supply Systems ◽  
Operating Pressure ◽  
Water Network ◽  
Small Water

Abstract The performance evaluation of an implemented water distribution network is in tight relation with the choice of adequate measures for water loss reduction. Hence, the consequences of placing the water network in a wrong performance category are bad and will conduct to unreasonably costs or considerable water loss volumes. Therefore, the evaluation of the water network performance level based on both Non-Revenue Water (NRW) and Infrastructure Leakage Index (ILI) indicators is to be recommended. This paper deals with the performance evaluation of water distribution systems based on the calculated performance indicators NRW and ILI. For this purpose, collected data for a period of one year from 12 Romanian small water distribution systems and two simplified average pressure determination methods were used.

Regulation response of pilot operated diaphragm pressure reducing valves: laboratory testing and impact on the performance of pressure control modes in water distribution systems

2021 ◽  
Author(s):  
Mouna Doghri ◽  
Sophie Duchesne ◽  
Annie Poulin ◽  
J.-P. Villeneuve
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Pressure Control ◽  
Quebec City ◽  
Real Time Control ◽  
Hydraulic Simulation ◽  
Pressure Setting ◽  
Time Control ◽  
The Impact

Pressure control is recognized as an efficient measure to reduce leaks from water distribution systems. The effectiveness of various pressure control modes, by means of pilot operated diaphragm pressure reducing valves (PRVs), is evaluated in this paper taking into account the sensitivity of the valve to various settings. First, the response of a PRV to consecutive pressure settings variations was experimentally evaluated in the hydraulic simulation laboratory of National Institute for Scientific Research (INRS). These experiments revealed that the studied valve reacts only when the pressure setting variation corresponds to at least 1/6 turn of the pilot valve. Second, a real case study from Quebec City, Canada, was simulated in order to evaluate the impact of the PRV response on three pressure control modes: fixed control, time based control, and real time control (RTC). The results show that RTC of pressure leads to leakage rate reduction on the studied network but that the PRV operational constraints limit the expected performance of RTC.

scholarly journals Pipe roughness calibration in water distribution systems using grey numbers

2010 ◽  
Vol 12 (4) ◽  
pp. 424-445 ◽  
Author(s):  
Stefano Alvisi ◽  
Marco Franchini
Keyword(s):  
Case Studies ◽  
Measurement Errors ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Taylor Series Expansion ◽  
Calibration Procedure ◽  
General Nature ◽  
Function Evaluation ◽  
Pipe Roughness

This paper presents a procedure based on the use of grey numbers for the calibration (with uncertainty) of pipe roughness in water distribution systems. The pipe roughness uncertainty is represented through the grey number amplitude (or interval). The procedure is of a wholly general nature and can be applied for the calibration (with uncertainty) of other parameters or quantities, such as nodal demands. In this paper, for the purpose of roughness calibration, a certain number of nodal head measurements made under different demand conditions is assumed to be available at different locations (nodes); all other topological and geometric characteristics of the system are considered to be known exactly. The general approach to pipe roughness calibration (taking account of uncertainty) focuses on identifying the grey roughness values which produce grey head values at the measuring nodes such as to encompass the observed values grouped on the basis of the different demand scenarios and, at the same time, have as small an ‘amplitude’ as possible. The proposed procedure was applied to two synthetic case studies and to one real network. The tests on the synthetic case studies show that the proposed procedure is able to correctly solve the inverse problem, i.e. it can identify the known grey roughness numbers even when they overlap; the same applies when the known grey roughness numbers collapse into known white roughness numbers. The test on the real case offers the possibility of highlighting the potentials of the procedure when applied within a context where measurement errors and other uncertainties are present. The procedure entails computing times that may become lengthy. However, it is possible to reduce these computing times considerably by replacing the hydraulic simulator—to which a number of calls must be made during the calibration procedure (for objective function evaluation)—with an approximation based on a first-order Taylor series expansion. This approach introduces acceptable approximations within the context of the problem considered.

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