Urban Water Distribution Systems Research Articles

The Roman aqueduct of Brigetio

The aim of the present study is to examine the literary sources and the archaeological material regarding the aqueduct of Brigetio. Based on the available information the paper examines the problem of the localization of the source which supplied the aqueduct. The catalogue includes the descriptions of the lead and terracotta water pipes from Brigetio now in the Roman collection of the Hungarian National Museum. The results are presented with regards to the construction of the urban water distribution system.

Evaluation of data driven models for pipe burst prediction in urban water distribution systems

ABSTRACTThe water distribution network is one of the most expensive parts of a water supply system. The fundamental variables of a network, material, diameter, length, age, and the hydraulic pressure of pipes are the factors that affect the pipe burst rate (PBR). Establishing a relationship among the burst rate and these factors is an important step to assess the conditions governing the network and preventing significant water leakage. Implementing the data-driven approach in PBR prediction is an effective method to find the relationship. In the present study, Grasshopper Optimization Algorithm-based Support Vector Regression (GOA-SVR), Gaussian Process Regression (GPR), and Artificial Neural Network (ANN) have been developed to predict PBR in an urban area. The results show that the GPR model outperforms other methods. Furthermore, the sensitivity analysis indicates that the pipe age has a negative effect on PBR modeling while the pipe length is the most relevant variable.

Analyzing the Sustainability of Urban Water Supply and Distribution System; In Case of Assosa Town Water Supply and Distribution System, Benishangul Gumuz National Regional State, Western Ethiopia (Technical Note)

The main objective of the study is to analysis sustainability of water supply and distribution system of Asossa town. While conducting this research, both primary and secondary data were collected and software such as water GEMSV8i, ArcGIS version10.4.1 and GPS Garmin72 were used. The water supply source of the study area yields 46.1 l/s but only 23.6 l/s of water used. The simulated result of extended period simulation showed that the performance of hydraulic parameters were pressure 21.05 % for pressure value 60 m head and the velocity of pipe flow showed that 84.86 % for velocity

Local indices within a mathematical framework for urban water distribution systems

In this paper, a set of local energetic indices for an urban water distribution system is proposed, together with a mathematical organization of the matter which is also able to incorporate many of...

Skeletonizing Pipes in Series within Urban Water Distribution Systems Using a Transient-Based Method

AbstractMany skeletonization methods are available to simplify the configuration of urban water distribution systems (WDS) to enable hydraulic modeling and analysis. However, these approaches are g...

Optimization of City Water Supply Networks on Their Structural and Functional Analysis Base

Based on the research results on the operation of urban water supply and distribution systems, the most rational ways of their improvement are identified in order to improve water supply and energy saving.

The effect of controlled pressure adjustment in an urban water distribution system on household demand

Abstract The effect of pressure adjustments on individual consumer water demand is presented in this paper. The study involved collecting and analysing data from two sites in an operational water reticulation system in South Africa. Pressures and flow rates were monitored at a few strategic locations and at 44 individual homes during a series of controlled pressure adjustments. A total of 25 weeks' data, recorded at 15-minute intervals, were analysed. The two systems were subjected to 11 pressure adjustments, lasting 2 weeks each. Results showed a positive relationship between the average pressure change and median consumer demand, where reduced pressure led to reduced consumer demand. The linear model suggested a relationship of ΔQ ≈ 0.5ΔP between the change in average pressure and the change in median consumer demand, at a consumer connection. However, notable variation from one consumer to the next was apparent. Based on night flow analysis, the on-site leakage on consumer properties (downstream of the consumer meter) represented about 25% of the total metered demand of the study sample. The field tests also confirmed that there are practical limits to the level of pressure reduction that can be attained, beyond which the consumers become unsatisfied with the pressure.

Occurrence and Spatial Distribution of Volatile Organic Compounds in Urban Drinking Water Distribution Systems

Volatile organic compounds (VOCs) in the urban drinking water distribution systems for two coastal cities (S City and L City) in China were analyzed. Health risk assessments of VOCs detected in tap water were performed, and the distribution characteristics of VOCs in the tap water pipe network were also investigated. Among 47 target VOCs, 16 compounds were detected, of which 11 were detected in both S City and L City. Halogenated hydrocarbons were the most commonly detected VOCs, with trihalomethanes (including bromodichloromethane, dibromochloromethane, and bromoform) having the highest detection frequencies (92%-100%). With the exception of bromodichloromethane and dibromochloromethane, the maximum concentrations of detected VOCs in both cities complied with the relevant limits regulated by the standards for drinking water quality (GB 5749-2006). For bromodichloromethane and dibromochloromethane, not only did their concentrations exceed the standard limits of GB 5749-2006 (60 μg·L-1 for bromodichloromethane and 100 μg·L-1 for dibromochloromethane), but their lifetime cancer risks (LCR) were estimated at unacceptable levels (>10-4). Therefore, these two compounds should be given sufficient attention or be classified as priority control pollutants in municipal water supply networks. In addition, the spatial distribution of eight VOCs with high detection frequencies (>90%) in the tap water pipe network of S City was investigated. The concentrations of VOCs (excluding toluene) in this urban drinking water distribution system gradually decreased with increasing distance from the drinking water treatment plant.

An assessment of sub-standard water pressure in South African potable distribution systems

Abstract 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 addressed the prevalence and extent of sub-standard pressures by using hydraulic models of potable WDS for 71 South African towns, located in 17 different South African municipalities geographically spread over the country. The hydraulic models included 539,388 modelled nodes, which were analysed to determine the number of nodes with sub-standard pressure heads during peak hour flow conditions. The results show that the residual pressure head was <24 m at 16.5% of the model nodes under peak hour flow conditions, with 6.7% of the nodes having pressure heads <12 m. In contrast, the results also report relatively high pressures in certain parts of the systems, far in excess of the minimum requirement, underlining the need for better pressure management at both high and low ranges. It was also noted that the South African design criterion is relatively stringent compared with some other countries and could potentially be relaxed in future.

Mixing at junctions in water distribution systems: an experimental study

The accurate prediction of solute transport in water distribution systems has become a critical component of efforts aimed at delivering clean drinking water safely to large urban populations. One of the central assumptions that water quality models have traditionally relied upon dictates that, in a four-way junction, two incoming flows of differing quality will mix perfectly to produce two outgoing flows of equal quality, and that such complete mixing occurs irrespective of the specific assemblage characteristics of any particular four-way junction. In this study, laboratory experiments were conducted in order to characterize solute mixing patterns at double-tee and wye junctions, both of which are commonly found in urban water distribution systems. Results show that mixing at double-tee junctions tends to be less than complete when the tee connectors are located adjacent to each other and mix to a greater degree than flows at cross junctions.

Awa: Using water distribution systems to transmit data

AbstractThis article presents Awa, a real‐time wireless monitoring solution for urban water distribution systems (WDSs). The Awa system is composed of a distributed network of low‐cost sensor nodes that can be quickly installed on water pipes. Rather than using conventional radio signals, which are attenuated in underground environments, the nodes use the actual water‐filled pipe as the transmission medium to communicate with one another. This permits the use of an already existing water infrastructure in the deployment of large wireless sensor networks. We describe the development and evaluation of novel and battery‐powered sensor nodes that can be magnetically clipped to valves and hard‐to‐access points in WDSs without requiring digging or cutting of pipes. A channel characterization is carried out and a number of data modulation schemes are evaluated across a 110‐m section of pipe in an operational WDSs. We identify a near‐optimal frequency (near 500 Hz) for transmitting data. We demonstrate communication at 100 bps across a real‐world water pipe using amplitude modulation. Not unlike radio‐frequency wireless, we also measure the highly nonstationary effects of multipath fading. The article also contains an in‐depth discussion about the opportunities that this emerging communication technology offers in the context of city‐wide leak detection and flow monitoring.

Probabilistic Analysis and Evaluation of Nodal Demand Effect on Transient Analysis in Urban Water Distribution Systems

AbstractThe implementation of nodal demands in current transient modeling and analysis in the urban water distribution system (WDS) is usually based on steady-state conditions or empirical-based ap...

Model for Optimal Operation of Water Distribution Pumps with Uncertain Demand Patterns

An optimization model is presented for pump operation based upon minimizing operation costs and indirectly the maintenance costs of pumps considering uncertainty of specified demand (load) curves. The purpose of this model is to determine pump operation to meet the uncertain demands as well as to satisfy the pressure requirements in the water distribution system. In addition, constraints on the number of pump (‘on-off’) switches are included as a surrogate to indirectly minimizing the maintenance costs. This model is a mixed integer nonlinear programming (MINLP) problem using a chance constraint formulation of the uncertain demand constraint. The optimization model was solved using the LocalSolver option in A Mathematical Programming Language (AMPL). The model was first applied to the operation of an example pumping system for an urban water distribution system (WDS) illustrating a reduction in operation costs using the optimization model. The optimization model with the chance-constraint for demand was applied for a range of demand satisfaction uncertainties. A decrease in the operation costs was observed with an increased uncertainty in demand satisfaction, which shows that the model further optimizes the operations considering the relaxed constraints. Model application could be extended to operations of pumping systems during emergencies and contingencies such as droughts, component failures etc.

Uncertainty in the analysis of urban water supply and distribution systems

AbstractConventionally, the design of urban water supply and distribution systems is based on the assumption that all the involved parameters are known a priori and remain unaltered throughout the life cycle of the system. However, significant uncertainties do appear during the analysis and design of these systems, such as the equivalent pipe roughness and the actual internal diameters of the pipes. To study these uncertainties, the water supply and the looped water distribution systems are studied separately. For the water supply system, these uncertainties are incorporated in the analysis of the system, using the extension principle of the fuzzy sets and a new operation of the fuzzy subtraction. Based on the calculation of head losses for each branch of the system, the nodal heads are obtained as fuzzy numbers. In regard to the looped water distribution system, a methodology is developed and proposed, based on the extension principle and leading to several optimisation problems with respect to the branches of the system. The aim of the proposed methodology is to determine the α-cuts and finally produce the shape of the membership function of flows in the branches of the system. Both methodologies are illustrated by numerical examples.

Improvement of sustainability indicators when traditional water management changes: a case study in Alicante (Spain)

Pressurized water systems are designed to guarantee the flow demanded by each user, considering the minimum required pressure. The pressurized water systems have increased water efficiency since their implantation, but they also increased the consumed energy and therefore, the greenhouse gasses emissions. The present manuscript develops the proposal of the sustainable indicators that were selected through deep review. These indicators are related to social-cultural, economic, and environmental criteria. Furthermore as novelty, they were described and applied on a pressurized water network, complementing the energy indexes usually used in the energy audit. To reach the improvement of the sustainability in water systems, new strategies should be developed to improve all sustainability criteria, included the water and energy efficiency. These strategies were developed and analyzed by using of specific hydraulic software (i.e., EPANET) and they were based on operation rules to estimate the hydraulic values (pressure and flow). The operation and the regulation strategies were applied on a particular case study, in which, the energy saving was 12.26%, the cost saving was 15.54%, the reduction of energy footprint of water was 15.04%, and the decrease of GHG was 12.26% although the increase of the distributed volume was 9.07%. Besides, the supply guarantee for both irrigation and urban water distribution systems was increased in the new proposal of water management. Finally, the proposal to replace of a pressure reduction valve by a sustainability recovery machine (e.g., pump working as turbine) contributed with a generation of renewable energy equal to 103,710 kWh/year.

Algorithmic development of life-cycle assessment: Application of urban water infrastructure systems in Iran

Urban infrastructure has an indisputable role in society's productivity. Since the residents' quality of life is dependent on the performance of infrastructure systems, devising procedures for monitoring such systems' current performance and predicting their future capabilities are necessary. Proper monitoring regime will take into account the remaining efficient performance time of the system and allocate appropriate maintenance and rehabilitation activities, thereby increasing the system productivity. Due to the vital role of water in people's lives and the immense size and complexity of urban water-distribution systems, the operation of urban water infrastructure is worthy of special attention in this regard. This paper presents an advanced algorithm for life-cycle assessment (LCA) of urban water infrastructure that is capable of determining the optimal time for system rehabilitation, taking into account both the economic and structural aspects of the system performance. The efficiency of the proposed approach is examined through the case study on a real water-distribution system in Iran. The system performance is simulated over its projected performance period via different breakage scenarios, and its efficiency is quantified by using a reliability-based indicator. The costs and benefits associated with the infrastructure performance are then evaluated, and its remaining useful operational life is estimated based on the projected reliability of the system and revenue impacts. The results of the case study imply that the developed method can be used to complement current practices as a proper tool for life cycle assessment of urban water infrastructure.

Prediction of the Future Condition of a Water Distribution Network Using a Markov Based Approach: A Case Study of Kampala Water

The increasing costs of managing urban water distribution systems coupled with limited budgets and new regulatory requirements has compelled water utilities to ensure that asset maintenance decisions move from a reactive to a proactive approach. This means that asset renewal decisions must shift from being made only when failures happen to well-planned priority- based replacement, repair and rehabilitation strategies. However the question of prediction of the future condition of the pipe network continues to trouble water utility managers because of the complexities in determining pipe conditions amidst poor data situations. Conventional approaches for prediction of pipe condition are skewed towards statistical analysis and do not consider failure history. Until now, there have been no approaches for prediction of future state based on pipe condition. This paper applies a Markov based approach as a decision support system to predict the future condition of a water distribution network. The approach is illustrated on a case study in Kampala Water, Uganda as a proof of concept. Data on pipe condition history per block is first checked to ensure it follows the Markovian process. Pipe condition has been based on a composite index that combines pipe age and break history. The goodness of fit has been evaluated using the X2-inference test. The Poisson distribution has been used to develop transition probability matrices required to forecast the state future condition of the water distribution network. The approach will help water utility managers optimize maintenance and repair decisions amidst budget limitations whilst taking into consideration both current and future states of the pipe network.

Index of network resilience for urban water distribution systems

A unique demographic shift towards urban centres has necessitated incorporation of sustainability principles in the tenets of urban infrastructure planning and design. Adopting resilience as the indicator of sustainability, this paper presents a novel index of network resilience (INR) for urban water distribution systems. The index developed in this paper incorporates six network attributes to develop a composite INR based on the topology of the water distribution systems. A multi-criteria analysis (MCA) using the weighted summation approach is employed to evaluate the alternative configurations which would satisfy the demand and other hydraulic requirements. Analytic hierarchy process (AHP) was assigned to assign weights to the attributes and was optimised for two scenarios: resilience and efficiency. Using the original configuration of Anytown network as the base case scenario, four alternative designs were developed. The results indicate that resilience of the system, in terms of increased robustness and redundancy, can be increased through a better topology without increasing material and energy investment. In addition, the results also indicate that there might be some potential trade-off between resilience and efficiency of flow for the network.

An Integrated Modeling Approach to Optimize the Management of a Water Distribution System: Improving the Sustainability While Dealing with Water Loss, Energy Consumption and Environmental Impacts

There is a strong link between water and energy in municipal water systems then the Alliance to Save Energy coined the term “Watergy” [1].Each component of the integrated water system contributes differently to the energy balance. With regard to urban water distribution systems (WDS), the pumping energy cost represents the single largest part of the total operational cost, also magnified by every litre of water lost to leaks. Even a small increase in operational efficiency may result in significant cost savings to the water industries.Therefore the inefficient management of water distribution systems results not only into depletion of water resources but also into energy consumption that increase CO2 emissions related also to the treatment of water volumes greater than needed, with use of excessive chemical components and consequent higher environmental global impact.The research outlined in this contribution was born with the aim to develop appropriate methodologies and tools to support the optimization of the WDS performance, in terms of water saving and reduction of energy consumptions and consequently environmental impacts. The integration of advanced WDS hydraulic modelling with a material and energy flow analysis is proposed herein, where the output of the hydraulic simulations permits to get more accurate input for a metabolic analysis of the system. Next phases of this research will test the integrated model under different scenarios, aimed at quantifying the environmental impact of different WDS management solutions by means of selected indicators.

Characteristics of pipe-scale in the pipes of an urban drinking water distribution system in eastern China

Pipes that carry drinking water have gradually aged. Events occurring with increasing frequency, such as substandard water quality in residential taps, red water, and black water, reveal the deterioration of the chemical stability of a drinking water distribution system (DWDS). Pipes in the DWDS serving City S, located in eastern China, were sampled to analyze the concentration and distribution of pollutants in pipe-scale of pipes of different materials, ages and diameters, and the factors (such as materials, age, and diameter) influencing the accumulation of pollutants were also investigated. The quantity of pipe-scale in the most commonly used gray cast iron pipe and ductile cast iron pipe (DN150) was 151.5–195.0 g·m−1 and 7.1–29.4 g·m−1, respectively. The concentration of heavy metals in pipe-scale was positively correlated with the quantity of pipe-scale (R2 = 0.874); the sequence of concentration of metals was Fe > Al > Mn, Zn > Pb, Cu > Cr, Cd. Galvanized steel pipe, with the highest degree of corrosion, had the highest concentration of heavy metals in pipe-scale. The morphology and composition of pipe-scale were substantially influenced by pipe material and age. For example, in the oldest galvanized steel pipe-scale, there was not only a large number of iron compounds but also some zinc composite oxides. In addition to hydrocarbons produced by microbial metabolism, there were microalgae metabolites and exogenous contaminants such as polycyclic aromatic hydrocarbons (PAHs). The concentrations of microbial metabolites increased with increasing service time.