Pipe hydraulic resistance correction in WDN analysis

Gröbner bases for solving ΔQ-equations in water distribution networks

Failures in the water distribution network are some most important factors in water losses, water shortage and dissatisfaction of users and secondary pollutions as well. This research aimed to analyze failure in water distribution networks during 2006-2008, for better water management. Daily failure reports in Ahvaz, Iran distribution network during 2006-2008, were collected from emergency department of Ahvaz water and Wastewater Company; thereafter, they were entered into an Excel database, also failures were defined by pipes type, pipe diameter, and cause of the failure, and finally the data were analyzed. Results indicated that asbestos and polyethylene pipes show maximum failures; maximum failure and fracture has occurred in pipes with 100 and 150 mm diameters. The most important factors affecting on failure were corrosion, traffic load and landslide. In addition, simultaneous influence of type and the diameter of the pipe on the failures were statistically significant. The depth of pipes establishment, corrosion and obsolescence of pipes as well as improper type of pipes were the most important causes of failures in Ahvaz Water Distribution Network. In this regard, upgrading pipe material setting standards and renewing water pipe network are the main strategies for failures minimization.

It has been proved that the standard representation of water demand in a Water Distribution Network (WDN) leads to pipe head loss errors as well that the fully satisfied demand regardless water pressure assumption is misleading. This follows that different algorithms have been developed in order to overcome these two drawbacks although separately and independently. Consequently, this paper introduces an alternative formulation of the Global Gradient Algorithm (GGA), referred to as UD-PD, which is able to solve uniformly distributed pressure driven demands along the pipes of a WDN in extended period simulations. In addition, this new scheme is tested against reference solutions and its performances are compared with the standard WDN models. Finally, the UD-PD is applied to a real WDN under pressure deficit conditions. Numerical results show that the hydraulic heads computed with the UD-PD result higher than those simulated with standard demand driven models and that the UD-PD is able both to capture the non linear behavior of the hydraulic head along the network and to correctly compute the flow inversion even in pressure driven conditions.

The water distribution network plays a key role in ensuring and providing a high quality of life for the public, with supply dependability being the most crucial component. A communities thrive is dependent on the availability of safe drinking water for its members. As the population of any community increases, the request for water also increases which imposes additional load to the existing water distribution system. As a result, the present water distribution system may become untrustworthy to meet the demand of the increased population. It is vital to provide an adequate and equitable quantity of water through a well-designed network of pipes in order to meet the ever-increasing water demand of the population. LOOP (Version 4.0) can be used to develop and simulate gravity and pumped water distribution systems that are novel, partially or completely functional. LOOP 4.0 is used to determine the cost of pipe network. EPANET is a computer program that models hydrodynamic behaviour in a pressurised pipe network over a long period of time. The Examination presents the hydraulic analysis of pipe network of Narangi area in Virar city using Loop 4.0 and EPANET 2.0. The results confirmed that the pressure at all junctions and velocities at all pipes are acceptable to deliver appropriate water to the study area’s network, as well as aiding in a better understanding of the study area’s pipeline system. The study also deals with the cost of distribution network.KeywordsLOOP 4.0EPANET 2.0Arc GISElevationNodesPipe networkPressureWater supply

Water Distribution Networks (WDNs) are crucial for meeting current and future urban water demands. Knowledge of future water demand at different time scales is fundamental for optimal WDN design and operations. Various predictive models of water demand have been proposed in the literature, ranging from traditional time series analysis to cutting-edge machine learning and deep learning techniques. However, the task of forecasting urban water demand remains mostly decoupled from the design of the optimal control of the related WDN. Current performance assessment of demand predictive models focuses predominantly on forecast accuracy, overlooking their practical implications on WDN operations. Meanwhile, the existing research on WDN management often assumes either perfect knowledge of future water demands or employs empirical approximations and aggregate statistics to estimate future water needs. This study bridges this gap by scrutinizing the actual operational value of water demand forecasts in designing optimal operations of WDNs.Here, we develop a forecast-informed optimal WDN control framework to evaluate the operational value of water demand forecasts for WDN operations. Our framework comprises two main modules. The first module computes water demand forecasts. We comparatively evaluate a suite of different forecasting models —including Seasonal Auto-Regressive Integrated Moving Average with eXogenous factors, Multilayer Perceptron, Convolutional Neural Network, and Long Short-Term Memory (a network augmented with an attention mechanism) —across various forecast horizons (1/6/12 hours and 1/3/7/14 days ahead). The most accurate forecasts are integrated into the second module, an economic nonlinear Model Predictive Control (MPC) algorithm designed to optimize WDN operations. Within this module, an Artificial Neural Network (ANN) – based surrogate model encapsulates the hydraulics of the physical WDN, enhancing the optimization process while reducing complexity.We demonstrate our forecast-informed optimal WDN control framework on a real WDN of a rural town with approximately 10,000 inhabitants. Water demand data collected in the Netherlands for a period of 10 years (2007-2017) at 5-minute resolution and corresponding meteorological data are used to train the water demand forecasting models. The MPC module computes the optimal control sequence for 7 pumps and 1 valve in the WDN to minimize pump energy costs while meeting water demands and ensuring safety storage in 5 tanks. Initial findings reveal that the ANN-based surrogate model can accurately incorporate the WDN characteristics (R2 > 0.85), facilitating its integration into the MPC for an efficient and simplified representation of a real-world WDN. Further, MPC fed by 24-hour ahead water demand forecasts achieves potential energy savings of approximately 18% compared to a benchmark rule-based control strategy. Our framework yields a versatile simulation-based optimization tool for evaluating the impact of demand forecasts on WDN management. Future research efforts will aim at refining and comparing deterministic and stochastic water demand forecasts within the MPC framework, under diverse operational objectives.

Future water demands and pipe roughness coefficients used in the design of water distribution networks (WDNs) have a high degree of uncertainty. Fuzzy analysis of WDNs provide how the uncertainties in independent or basic parameters (such as nodal demands and pipe roughness coefficients) are propagated to dependent or derived parameters (such as pipe flows, pipe velocities, and available pressure heads). Usually demand dependent analysis is used for such analysis. A WDN may be pressure deficient or may become pressure deficient because of high pipe roughness or inadequate pump pressure and may not be able to meet desired demands at all nodes. Thus, it is desirable to consider the nodal outflows as unknown and as a function of available pressure heads under pressure-deficient conditions. An approach for fuzzy analysis of a WDN that takes into account pressure-deficient condition using node flow analysis is presented in this paper. The proposed methodology is illustrated with an example network taken from literature. The methodology is useful in identifying vulnerable zones in WDNs and can be extended for reliability analysis under uncertainty of nodal demands and pipe roughness coefficients. Comparison of results with usual demand-dependent analysis shows that proposed method is better for identifying vulnerable zones.

Drinking water distribution networks are important because they provide water to meet basic human needs, and to protect humans in the event of fires and other public emergencies. With aging infrastructure, there is an urgent need to design water distribution networks to ensure safety and reliability of service in the future. The uncertainty that surrounds future scenarios of climate-induced drought, population levels, and urbanization patterns – all factors that influence water demand – means that a system design chosen today may be inadequate to meet future demands in a water distribution network. Water utilities often have to plan the design of their water distribution network with only limited information on future water demand levels. For example, if water demand in the future is higher than the level predicted at the time of design, then a municipality will eventually have to retrofit the system, perhaps at great expense, to meet the unanticipated water demand. Thus, there is a need for methods to design networks to minimize the need for future system retrofit under uncertain demands, and to make networks economically robust. In this paper a new framework is presented to design water distribution networks for economic robustness. Economic robustness supplements the least-cost optimality criterion by providing a measure of the variability involved in retrofit costs of a system under uncertain future conditions. In the new framework, water demand projected at the end of a 20-year planning period is treated as an uncertain quantity and modeled as a random variable with an error probability density function (PDF). In the proposed framework, new criteria such as the expected value and standard deviation of retrofit cost are developed to evaluate the economic robustness of water distribution networks. The framework is applied to a simple network, with comparison of design alternatives done on the basis of pipe cost and expected retrofit cost. The results obtained indicate that surplus hydraulic capacity lowers the uncertainty of future retrofit costs and increases confidence of retrofit cost estimates. Consequently, the results substantiate the intuitive understanding of the benefits of surplus hydraulic capacity in a system.

A hydraulic model was developed in order to evaluate the potential energy recovery from the use of centrifugal pumps as turbines (PATs) in a water distribution network characterized by the presence of private tanks. The model integrates the Global Gradient Algorithm (GGA), with a pressure-driven model that permits a more realistic representation of the influence on the network behaviour of the private tanks filling and emptying. The model was applied to a real case study: a District Metered Area in Palermo (Italy). Three different scenarios were analysed and compared with a baseline scenario (Scenario 0 – no PAT installed) to identify the system configuration with added PATs that permits the maximal energy recovery without penalizing the hydraulic network performance. In scenarios involving PAT on service connections, the specification of PAT operational parameters was also evaluated by means of Monte Carlo Analysis. The centralized solution with a PAT installed downstream of the inlet node of the analysed district, combined with local PATs on the larger service connections, proves to be the most energy-efficient scenario.

Water distribution systems are regarded as large sparse graphs with complex network characteristics. Topological aspects of system resilience, viewed as the antonym to structural vulnerability, are assessed in connection with the network architecture, robustness and loop redundancy. Deterministic techniques from complex networks and spectral graph theory are utilized to quantify well-connectedness and estimate loop redundancy in the studied benchmark networks. By using graph connectivity and expansion properties, system robustness against node/link failures and isolation of the demand nodes from the source(s) are assessed and network tolerance against random failures and targeted attacks on their bridges and cut sets are analyzed. Among other measurements, two metrics of meshed-ness and algebraic connectivity are proposed as candidates for quantification of redundancy and robustness, respectively, in optimization design models. A brief discussion on the scope and relevance of the provided measurements in the analysis of resilience of water distribution networks is presented.

TECHNOLOGY AND CULTURE Book Reviews 1033 formulate a plan to tap the Colorado River. In 1952, Freese prepared a groundbreaking document when on behalf of all the state’s engi­ neers he presented a statewide water plan entitled “A Water Policy for Texans.” Always innovative, Freese and Nichols was one of the first organiza­ tions to use computers, preparing an analysis of water distribution networks in 1957. Work in the 1960s reflected a new national aware­ ness of the environment and a heightened understanding of the im­ pact of the engineer’s work on nature and society. During the 1980s modernized operations and broadened services provided archaeolog­ ical research, management plans for fish and wildlife, and architec­ tural and historic surveys. Cited in the success and longevity of the firm is “its ability to govern and assimilate change” (p. 345). But a company does not deal with change, people do that. Much to their credit, those who managed the firm fostered a high degree of professionalism among the engineers they hired and at the same time encouraged them to look on civil engineering foremost as a public service. It is a formula that worked. It is unfortunate that Simon Freese did not live to see the publica­ tion of this book and to enjoy the accolades it will surely receive. Meticulously prepared, objective, and contextual, there is no question that it stands as a landmark in engineering histories. What a pity the founding principals of grand old firms such as Modjeski and Masters, Robinson and Steinman, and Morrison Knudson did not leave similar historical legacies. William Worthington Mr. Worthington specializes in the history of engineering at the National Museum of American History. The Politics ofTechnological Change in Prussia: Out ofthe Shadow ofAntiq­ uity, 1809—1848. By Eric Dorn Brose. Princeton, N.J.: Princeton University Press, 1993. Pp. xiii + 290; notes, bibliography, index. $39.50. While some historians of Prussia have treated the state as an auton­ omous entity (Beamtenstaat) between the Napoleonic Wars and the Revolutions of 1848, others have argued that it was dominated by the aristocracy (Junherstaat). Another major historiographical approach gives state officials credit for promoting Prussia’s early stages of in­ dustrial development. Eric Brose provides a quite different picture. By using technology policy to investigate contending groups of state officials, their visions of past and future, and their relationships with businessmen, Brose develops a new conception of the nature of the Prussian state and its relationship to civil society in the early 1800s. Brose proceeds in a topical manner. He develops a theoretical posi­ 1034 Book Reviews TECHNOLOGY AND CULTURE tion concerning the state made up of contending departments and agencies interconnected with various sections of society, before turn­ ing to discussions of state agencies like the Business Department, the Mining Corps, the army’s technical establishment, and the Overseas Trading Corporation (Seehandlung). The Business Department and the Seehandlung sought to develop a rural industrial base, while the Mining Corps developed its own mines, forges, and foundries, based on techniques from the 1500s and 1600s. Although not significant in terms of overall investment, these strategies produced improvements welcomed by businessmen in the 1810s and 1820s. By the 1830s and 1840s, however, the visions of development promoted by state offi­ cials were no longer seen by businessmen as beneficial. Although initially ambivalent about modern technology, members of the army began supporting the development of railroads in the 1830s against other segments of the state which saw railroads as diverging from their visions of an appropriate future. King Frederick William III allowed competing approaches in the state, but sided with proponents of mercantilist change in the 1810s and 1820s, and supported a law beneficial to railroads in 1838. His son supported railroads also, but increasingly turned to reactionary policies in the 1840s. Thus, seg­ ments of tfie state provided an impetus to technological change until the 1830s and 1840s, when state officials, soldiers, and businessmen, disagreeing about what policies should be followed and who should control production, became increasingly alienated from one another. Brose provides a valuable corrective to visions of a monolithic Prus­ sian state. Competition and even chaos were common. The stress on antiquity was...

Water Distribution Networks are one of the most important infrastructures. The success of a water distribution network depends upon its capability and efficiency to cater water demand and available residual pressures at consumer ends. Conventionally, Demand Driven Approach is used for designing and analyzing a water distribution network. But this approach fails to consider practical situations that can arise in an operational system like valve closure, pipe burst, pump failure, source failure, fire flow, DMA operations and their adverse effects on the network. Practically, residual pressures in the system vary quiet often and so the discharges at consumer ends. As the pressure increases, discharge also increases and vice-versa. Therefore discharges/demands depend upon the available residual pressure. This approach of analyzing a water distribution network is known as Pressure Driven Analysis. The aim of the paper is to study both Demand Driven Approach and Pressure Driven Approach and compare their results.

A Data Driven Approach for Resilience Analysis of Water Distribution Networks

Effects of Data Uncertainty on Multi-species Qualitative Modeling and Pressure Dependent Analysis of Water Distribution Networks Using the Elementary Effect Method

The fixed demand hydraulics engine of EPANET software in its original form is not suitable for analysis of water distribution networks with low operating pressures. A modification of EPANET desktop for pressure driven demand analysis, employing emitter modeling of demands, is presented. The introduced version is able to work in a fully transparent way with standard EPANET network files and could be developed into other EPANET-toolkit based applications following the exact procedure as with standard EPANET. A simple network example used to demonstrate the operation of the system. Finally an illustrative case study of the model application is presented.

An analysis that considers a relationship between nodal demand and available nodal pressure to determine the outflow at that node is carried out and mostly referred as pressure-dependent analysis (PDA). Further, not only the outflow but some demand itself such as leakage losses and water demand at sprinklers, faucets etc., are also considered dependent on pressure. Several node head-flow relationships (NHFRs) have been suggested along with the methodologies for their solution in the last three decades. Further, efforts have been also made to carry out PDA by using an efficient DDA based hydraulic network solver, EPANET. The PDA has been used in tackling a variety of problems on water distribution systems such as: assessing reliability, reliability-based design, parameter calibration, vulnerability analysis, placement of isolation valves, water quality analysis, flushing of contaminated water, leakage modelling, and multi-objective evolutionary optimization. This paper provides a complete development in PDA along with future research need.