Large Water Supply System Research Articles

Generalized Impedance-based Transient Analysis for Multi-branched Pipeline Systems

Transient analysis of multi-branched pipeline systems is generalized by the development of an impedance method. Both open and closed boundaries of branched pipeline elements were implemented in the analytical development of a reservoir multi-branched pipeline valve system, in which impedance and transient responses performance were compared with those of conventional approaches. To address realistic boundary conditions along the branched element, a partially opened boundary condition was implemented in the impedance expression of the branched pipeline system. The performance of the generalized multi-branch impedance method was evaluated on a large water supply system with 10 minor branches from the actual system. The impact of the designated branches was evaluated using the pressure root-mean-square error (RMSE) and the energy spectral density difference between the original and skeletonized systems. Combinations of multiple branches for certain flow conditions were identified based on the holistic response for both the frequency and time domains. The proposed method can be a useful alternative to effectively address the skeletonization issue for pipeline systems with multi-branched elements.

Hazardous event analysis of microbiological contamination in risk management of large water supply systems

Hazardous event analysis of microbiological contamination in risk management of large water supply systems

ВЕЩЕСТВЕННЫЙ СОСТАВ ТОРФОВ ТИМИРЯЗЕВСКОГО БОЛОТА (ТОМСК, ЗАПАДНАЯ СИБИРЬ)

Актуальность. Болота одновременно являются индикатором состояния окружающей среды в целом и связанных с болотами речных и подземных вод в частности. Это определяет необходимость изучения состояния болот, особенно в районе размещения крупных водозаборов, например, Томского подземного водозабора. Цель: выявление изменений по глубине торфяной залежи Тимирязевского болота (западная окраина г. Томска, Западная Сибирь) химического состава торфов (кислотных вытяжек) и ассоциаций минеральных включений в торфяной залежи как индикаторов природно-антропогенных условий формирования болота. Методы: методы определения химического (включая масс-спектрометрический с индуктивно связанной плазмой) и минерального состава (сканирующая электронная микроскопия с локальным энергодисперсионным анализом), статистические методы. Результаты и выводы. Для переходного Тимирязевского болота в долине реки Томь у г. Томска выявлено неоднородное изменение зольности, Al, Ti, Cr и ряда других элементов с максимумами в верхней и нижней частях торфяной залежи пропорционально источнику минерального вещества (в верхней части залежи – пылевые выпадения, в нижней подстилающие грунты). С учетом данных, ранее полученных на Васюганском болоте, сделано предположение о наличии общего механизма формирования вещественного состава торфов и трансформации минерального вещества в болотах на основе фильтрационных свойств среды. Основные черты указанного выше механизма заключаются в биохимической трансформации минеральных веществ, поступающих из атмосферы, с поверхностным и подземным стоком с суходолов, в результате чего в деятельном горизонте вещество находится во взвешенном, коллоидном и растворенном состоянии, а в инертном горизонте с большей интенсивностью формируются минеральные фазы. На поверхности последних, а также на частицах гидроокислов происходит соосаждение ряда микроэлементов и формирование аутигенных минералов, в том числе фосфатов редкоземельных элементов. Скорость и направленность этих процессов зависит от геоморфологических и гидрологических условий, определяющих возникновение и функционирование геохимических барьеров.

Optimal energy management of a renewable microgrid integrating water supply systems

The interdependence between the power grid and water supply system (WSS) provides opportunities for energy conservation. However, the existing water supply flexibility has not been fully developed, resulting in an unsatisfactory effect. To address the problem, this paper proposes an optimal energy management strategy for a renewable microgrid (MG) integrating WSSs. First, a novel supply model that evaluates the interdependence between the large WSS and several islanded sub-systems, hydraulic stability, and desalination characteristic is established, in order to reduce the hydraulic coupling constraints and ensure water supply safety. To achieve an optimal performance of the MG integrating WSSs, a novel two-stage dispatching method is designed, where the day-head decisions fully consider the real-time power fluctuation, and the real-time stage corrects renewable generation deviation and supports external grid. Additionally, a two-stage algorithm is proposed to efficiently solve the scheduling problem. Simulation studies on a MG integrating WSSs indicate the proposed energy management strategy can reduce the water supply loss by 5.2%, and improve the MG economy by 19.5%, while supporting the external grid (EG).

Impacts of alien plant invasions on water resources and yields from the Western Cape Water Supply System (WCWSS)

A key motivation for managing invasive alien plant (IAP) species is their impacts on streamflows, which, for the wetter half of South Africa, are about 970 m3∙ha−1∙a−1 or 1 444 mill. m3∙a−1 (2.9% of naturalised mean annual runoff), comparable to forest plantations. However, the implications of these reductions for the reliability of yields from large water supply systems are less well known. The impacts on yields from the WCWSS were modelled under three invasion scenarios: ‘Baseline’ invasions; increased invasions by 2045 under ‘No management’; and under ‘Effective control’ (i.e. minimal invasions). Monthly streamflow reductions (SFRs) by invasions were simulated using the Pitman rainfall−runoff catchment model, with taxon-specific mean annual and low-flow SFR factors for dryland (upland) invasions and crop factors for riparian invasions. These streamflow reduction sequences were input into the WCWSS yield model and the model was run in stochastic mode for the three scenarios. The 98% assured total system yields were predicted to be ±580 million m3∙a−1 under ‘Effective control’, compared with ±542 million m3∙a−1 under ‘Baseline’ invasions and ±450 mill. m3∙a−1 in 45 years’ time with ‘No management’. The ‘Baseline’ invasions already reduce the yield by 38 mill. m3∙a−1 (two thirds of the capacity of the Wemmershoek Dam) and, in 45 years’ time with no clearing, the reductions would increase to 130 mill. m3∙a−1 (capacity of the Berg River Dam). Therefore IAP-related SFRs can have significant impacts on the yields of large, complex water supply systems. A key reason for this substantial impact on yields is that all the catchments in the WCWSS are invaded, and the invasions are increasing. Invasions also will cost more to clear in the future. So, the best option for all the water-users in the WCWSS is a combined effort to clear the catchments and protect their least expensive source of water.

Management of Non-Revenue Water (NRW) on Sustainable Basis

Every large water supply system faces the problem of efficient management of NRW in the distribution network and this challenge when managed well will solve acute water shortage in the entire universe. The purpose of this article is to demonstrate how NRW can be efficiently managed on sustainable basis and how an effective program of work can be executed.

Pump Scheduling for a Large Water Distribution Network. Milan, Italy

Large water distribution networks require efficient use of their resources. One of the ways to become more efficient is to reduce the energy consumption due to pumping systems [1][2]. In the European context the city of Milan has a large water supply system for 1.3 million inhabitants and around 4.0 million commuters, which is supplied entirely by 26 pumping stations. The system currently supplies its ∼50,000 customers with 103 pumps which are actively operated during the day [3]. In previous years a pump scheduling algorithm has been proposed to the utility for a Pressure Management Zone (PMZ) in the south of the city named Abbiategrasso containing only 4 pumps [4][5]. However, it is of the interest for the utility to extend the analysis to the whole system [6][7]. For that reason it is necessary to perform a proper pump scheduling. The solution proposed here, is a Multi-Objective Optimization (MOO) for the energy consumption reduction of the whole Water Distribution Network (WDN) using an EPANET model of the whole network. Results show that there is room for improvement of energy and pressure management in the system. The solution presented here can be applied to other utilities with similar challenges.

Assessing the relative effects of emissions, climate means, and variability on large water supply systems

AbstractSome of the greatest societal risks of climate change rise from the potential impacts to water supply. Yet prescribing adaptation policies in the near term is made difficult by the uncertainty in climate projections at relevant spatial scales and the conflating effects of uncertainties in emissions, model error, and internal variability. In this work, a new framework is implemented to explore the vulnerability of reservoir systems in the northeastern U.S. to climate change and attribute vulnerabilities to changes in mean climate, natural variability, or emission scenarios. Analysis of variance is used to explore the contributions of uncertainties to system performance. Diagnosing the relative risks to water supply will help water resource engineers better adapt to uncertain future conditions. The results indicate that uncertainty in water supply system performance can be attributed mostly to uncertainty in internal variability over policy‐relevant planning horizons, and thus, adaptation efforts should focus on managing variability.

Screening robust water infrastructure investments and their trade-offs under global change: A London example

We propose an approach for screening future infrastructure and demand management investments for large water supply systems subject to uncertain future conditions. The approach is demonstrated using the London water supply system. Promising portfolios of interventions (e.g., new supplies, water conservation schemes, etc.) that meet London’s estimated water supply demands in 2035 are shown to face significant trade-offs between financial, engineering and environmental measures of performance. Robust portfolios are identified by contrasting the multi-objective results attained for (1) historically observed baseline conditions versus (2) future global change scenarios. An ensemble of global change scenarios is computed using climate change impacted hydrological flows, plausible water demands, environmentally motivated abstraction reductions, and future energy prices. The proposed multi-scenario trade-off analysis screens for robust investments that provide benefits over a wide range of futures, including those with little change. Our results suggest that 60 percent of intervention portfolios identified as Pareto optimal under historical conditions would fail under future scenarios considered relevant by stakeholders. Those that are able to maintain good performance under historical conditions can no longer be considered to perform optimally under future scenarios. The individual investment options differ significantly in their ability to cope with varying conditions. Visualizing the individual infrastructure and demand management interventions implemented in the Pareto optimal portfolios in multi-dimensional space aids the exploration of how the interventions affect the robustness and performance of the system.

Pipeline Networks E-modelling Based on CityComTM Technology: Experience of Industrial Implementation for Large Water-supply Systems

In the article below the author describes best practices of his company's 25-years experience in the field of development and industrial implementation of complex corporate-level software systems for solutions to everyday production and planning tasks in water supply.All software systems described have been developed using the specialized CityCom™ platform that includes instrumentation tools not only for GIS-based inventory and hydro-modeling but also for dispatch management, accident localization control, providing events logs & analysis (flow parameters, damages, works, machinery usage, diagnostics), planning of capital repairs and etc.The basic principle underlying the software systems provided is the main tenet of informatics science: any data has to be identified and stored only once and in one place. So all of the CityCom™ corporate-level projects use a single corporate database that consist of hundreds of tables where all the data is stored in accordance with the above-mentioned principle.The feature of CityCom™ that appears to be most in demand is the ability to perform hydraulic modeling with no limits imposed on the following parameters: network dimension, number of loops, number of sources and pump stations working simultaneously. However, a key feature of CityCom™ hydro-modeling instrumentation is that it can be used not as «standalone» application but as an integral part of a complex system combining all aspects of water-supply enterprise data modeling solution.The economic advantages of its implementation are ensured by:- optimizing of pipeline networks topology and parameters (reconstructions and switching);- optimizing of hydraulic modes according to diurnal fluctuations of water consumption (dispatching of current switches and pump stations control);- reducing the number of accidents as well as defects and damages (10-12% per year during the first 5-6 years, then stabilizing) and as a result, reducing the cost of repairs;- reducing of potable water loss down to 5..6% of water supply volume;- improving ergonomics and staff productivity.All implementations for water supply and sewerage systems are located in Russia. Largest of them in terms of scale are in the cities (population / pipelines network length): Nizhny Novgorod (1.300.000/5.000km), Novokuznetsk (550.000/1.800km), Naberezhnye Chelny (530.000/ 1.400km), Yoshkar-Ola (270.000/1.300km).Payback of expenses for implementation of the above has made from 2 to 5 years.

A comparison between different techniques for water network sectorization

Water network partitioning represents one of the best methodologies for improving water balance and pressure control of a water distribution system in order to reduce water leakage. These techniques can be applied with greater effectiveness defining a smaller permanent network district, called a District Meter Area (DMA), achieved by the insertion of gate valves and flow meters. If the DMAs are isolated subsystems (sectors), such that each zone is fed by its water source (or water sources) by closing gate valves in the network pipes that link the DMAs, the process can be called water network sectorization (defining an isolated DMA (i-DMA)). The traditional criteria for the design of network DMAs and i-DMAs are based on empirical suggestions (number of properties, length of pipes, etc.) and on approaches such as ‘trial and error’, even if used together with hydraulic simulation software. Nevertheless these indications and procedures are very difficult to apply to large water supply systems because the insertion of gate valves modifies the original network layout and may worsen, also considerably, the hydraulic performance of the water network. Recently some techniques, based on graph theory principles that allow simplification of the network partitioning and sectorization, and to find optimal solutions heuristically, have been proposed in the literature. In this paper the sectorization problem has been examined comparing different techniques, proposed by the authors, using the same water networks and performance indices and testing different possible i-DMA layouts.

Effect of scenario assumptions on climate change risk estimates in a water resource system

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 59:149-160 (2014) - DOI: https://doi.org/10.3354/cr01203 Effect of scenario assumptions on climate change risk estimates in a water resource system Ke Li1,2,3, Jingyao Qi1,*, Casey Brown3, Julia Ryan3 1State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China 2Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China 3Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Massachusetts 01002, United States *Corresponding author: qjy_hit@yahoo.cn ABSTRACT: The common approach in evaluating the impacts of climate change on a water resource system begins with downscaling general circulation model (GCM) projections, estimating resultant streamflow via a hydrological model, and assessing impacts with a water resource system model. An alternative methodology, described as ‘decision scaling,’ links a bottom-up approach with climate information including GCM projections through a decision analysis framework. One advantage of this approach is that the effects of different assumptions related to the processing of climate simulations can be directly characterized. This paper demonstrates the usefulness of the decision-scaling methodology by examining how probability distribution function choice influences the modeling of climate-change-impact uncertainty, and how, in turn, this affects projections of water supply systems. The approach is demonstrated in an analysis of the risk of climate change impacts on a large water supply system located in central Massachusetts, USA. KEY WORDS: Climate change · Water resource system · General circulation model · Risk estimates Full text in pdf format PreviousNextCite this article as: Li K, Qi J, Brown C, Ryan J (2014) Effect of scenario assumptions on climate change risk estimates in a water resource system. Clim Res 59:149-160. https://doi.org/10.3354/cr01203 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 59, No. 2. Online publication date: March 25, 2014 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2014 Inter-Research.

Least Economic Cost Regional Water Supply Planning – Optimising Infrastructure Investments and Demand Management for South East England’s 17.6 Million People

This paper presents a deterministic capacity expansion optimisation model designed for large regional or national water supply systems. The annual model selects, sizes and schedules new options to meet predicted demands at minimum cost over a multi-year time horizon. Options include: supply-side schemes, demand management (water conservation) measures and bulk transfers. The problem is formulated as a mixed integer linear programming (MILP) optimisation model. Capital, operating, carbon, social and environmental costs of proposed discrete schemes are considered. User-defined annual water saving profiles for demand management schemes are allowed. Multiple water demand scenarios are considered simultaneously to ensure the supply–demand balance is preserved across high demand conditions and that variable costs are accurately assessed. A wide range of supplementary constraints are formulated to consider the interdependencies between schemes (pre-requisite, mutual exclusivity, etc.). A two-step optimisation scheme is introduced to prevent the infeasibilities that inevitably appear in real applications. The model was developed for and used by the ‘Water Resources in the South East’ stakeholder group to select which of the 316 available supply schemes (including imports) and 511 demand management options (considering 272 interdependencies) are to be activated to serve the inhabitants of South East of England. Selected schemes are scheduled and sized over a 25 year planning horizon. The model shows demand management options can play a significant role in the region’s water supply and should be considered alongside new supplies and regional transfers. Considering demand management schemes reduced overall total discounted economic costs by 10 % and removed two large reservoirs from the least-cost plan. This case-study optimisation model was built using a generalised data management software platform and solved using a mixed integer linear programme.

An Automated Tool for Smart Water Network Partitioning

Water Network Partitioning (WNP) represents the application of the “divide and conquer” paradigm to a Smart WAter Network (SWAN) that allows the improved application of techniques for water balance and pressure control. Indeed, these techniques can be applied with greater effectiveness by defining smaller permanent network parts, called District Meter Areas (DMAs), created by the insertion of gate valves and flow meters. The traditional criteria for the design of network DMAs are based on empirical suggestions (number of properties, length of pipes, etc.) and on approaches such as ‘trial and error’, even if used together with hydraulic simulation software. Nevertheless, these indications and procedures are very difficult to apply to large water supply systems because the insertion of gate valves modifies the original network layout and may considerably worsen the hydraulic performance of the water network. The proposed tool, based on some graph partitioning techniques, commonly applied in distributed computing, and on an original optimisation technique, allows the automatic design of a WNP comparing different possible layouts that are compliant with hydraulic performance. In this paper, the methodology was tested on a real case study using some performance indices to compare different WNPs. The proposed tool was developed in Phyton and integrates graph partitioning, hydraulic simulation techniques and a heuristic optimisation criterion. It allows the definition of DMAs with resulting performance indices that are very similar to the original network layout.

The Variable-Frequency Speed Governing and Constant Pressure Water Supply System Based on PID Fuzzy Control Algorithm

The paper revolves around the design of large and medium-size water supply system in which the adjustable modifying factor PID fuzzy control algorithm is adopted. The design offers a solution which is targeted at the closed-loop control by analysis mathematical model is not efficiently achievable, because of the complicated water pipelines and numerous curves, as well as the fact that the objects to be controlled are characterized by their high order, big lagging, close coupling, non-linear and time-varying parameters. The design can enhance the stability and reliability of the frequency control water supply system.

PLIO: a generic tool for real-time operational predictive optimal control of water networks

This paper presents a generic tool, named PLIO, that allows to implement the real-time operational control of water networks. Control strategies are generated using predictive optimal control techniques. This tool allows the flow management in a large water supply and distribution system including reservoirs, open-flow channels for water transport, water treatment plants, pressurized water pipe networks, tanks, flow/pressure control elements and a telemetry/telecontrol system. Predictive optimal control is used to generate flow control strategies from the sources to the consumer areas to meet future demands with appropriate pressure levels, optimizing operational goals such as network safety volumes and flow control stability. PLIO allows to build the network model graphically and then to automatically generate the model equations used by the predictive optimal controller. Additionally, PLIO can work off-line (in simulation) and on-line (in real-time mode). The case study of Santiago-Chile is presented to exemplify the control results obtained using PLIO off-line (in simulation).

Determination of fecal contamination indicator sterols in an Australian water supply system

This paper reports a reconnaissance survey of the concentrations of sterol compounds (as indicators of fecal contamination) in a large water supply system in southeast Australia comprising a network of rivers, channels, and drains. Levels of coprostanol and cholestanol were determined in surface water and bottom sediment using gas chromatography-mass spectrometry analysis across 17 strategic sampling sites and over 12 months. Clear differences in the levels of fecal contamination were observed among sites. Four sites routinely contained high levels of the fecal indicator sterols indicated from surface water and sediment sample analysis. Coprostanol concentrations at each location varied from 0 ng/L at the reference site to 11,327 ng/L in a surface water sample of a drain directly downstream of a knackery. The majority of the sites contained coprostanol in the range of 500 to 800 ng/L. Since no fecal-associated sterol compounds were detected at the external reference sites, these were assumed to be free from fecal contamination. Sewage water discharge and/or substantial water runoff maybe the principal factors contributing to fecal contamination of the supply drains and channels.

A general Bayesian framework for calibrating and evaluating stochastic models of annual multi-site hydrological data

Summary Multi-site simulation of hydrological data are required for drought risk assessment of large multi-reservoir water supply systems. In this paper, a general Bayesian framework is presented for the calibration and evaluation of multi-site hydrological data at annual timescales. Models included within this framework are the hidden Markov model (HMM) and the widely used lag-1 autoregressive (AR(1)) model. These models are extended by the inclusion of a Box–Cox transformation and a spatial correlation function in a multi-site setting. Parameter uncertainty is evaluated using Markov chain Monte Carlo techniques. Models are evaluated by their ability to reproduce a range of important extreme statistics and compared using Bayesian model selection techniques which evaluate model probabilities. The case study, using multi-site annual rainfall data situated within catchments which contribute to Sydney’s main water supply, provided the following results: Firstly, in terms of model probabilities and diagnostics, the inclusion of the Box–Cox transformation was preferred. Secondly the AR(1) and HMM performed similarly, while some other proposed AR(1)/HMM models with regionally pooled parameters had greater posterior probability than these two models. The practical significance of parameter and model uncertainty was illustrated using a case study involving drought security analysis for urban water supply. It was shown that ignoring parameter uncertainty resulted in a significant overestimate of reservoir yield and an underestimation of system vulnerability to severe drought.

Reducing uncertainty in the hydraulic analysis of canals

British Waterways is the largest navigation authority in the UK, managing a network of 3200 km of inland waterway. Central to this function is the management of a large and complex water supply system: water is transferred across the network for resource management, to maintain navigation, for sale to third parties and for flood relief. Understanding the movement of water is essential to the effective and efficient management of this system. One-dimensional hydraulic models are routinely employed by water engineers to investigate such regimes throughout the UK. This paper describes recent studies aimed at reducing the uncertainties associated with the application of such models. This was achieved with a programme of primary research that included extensive site surveys, hydraulic trials and modelling. The outputs of this work include: validation of Manning's roughness representation for canals; determination of roughness coefficients for a range of bed and bank protection types; development of a practical relationship for determining the effective roughness of vegetated canals; and the quantification of the impact of canal constrictions. This work is of interest to consultants, researchers and those who undertake hydraulic modelling studies of canal systems.

The Structure of Bulk Water Supply Costs in Japan : a Hedonic Cost Function Approach

There are four types of water supply systems in Japan such as large water supply systems, small water supply systems, bulk water supply systems and small private water supply systems. While water supply systems have at least three activities such as water intake, water purification and water delivery, the only bulk water supply systems don't have water delivery but have water intake and water purification. Bulk water supply systems are owned by prefecture or water supply authority which is established by some local governments, so bulk water supply systems therefore are thought of as they aim to increase productivity of water intake and water purification activities through widespread coordination.The purpose of this study is to analyze the cost structures of bulk water supply systems. The process of this analysis is as follows: (1) estimate the translog cost function and adopt hedonic output specification which contains some product quality variables, (2) include network variable in the cost model and identify economy of density and economy of scale. We obtain the results that some product quality variables have positive impacts to the cost structure and economy of density does exist (1.685) whereas economy of scale shows a constant return to scale (1.020) at the sample mean point.JEL classification: L95, L11