Reliability Analysis of Benchmark Water Distribution System

Population growth, urbanization, and people’s preferences for water to be brought closest to the home, compel operators with little or no technical know-how on Water supply and distribution systems (WDSs) hydraulics to often introduce new nodes into the network to extend water to consumers. The outcome is operational challenges with some areas not getting adequate supply because of inappropriate pipe routing and sizing, and pressure build up in some sections resulting in pipe bursts during operation. The study evaluated the hydraulic performance of the Lawra township water distribution system for improved service delivery using hydraulic-based models. The Flowius application, Google Earth, Geographical information system (GIS) were the data collection tools employed, while EPAnet and Microsoft Excel software were used to analyse the data. The hydraulic parameters within a 24-hour period in the existing and proposed network were monitored. The existing system runs for a maximum of five hours (00:00am-05:00am) when tested with pressure value (5.3 m) not meeting the minimum pressure requirement of 10 m. The remaining hours of the day depicted negative pressures signifying system unbalance. There were significant head losses in all the three (3) zones (A 24.25 m/km, B 161.66 m/km and C 72.96 m/km) with zone B recording almost thirty-two (32) times higher than the recommended standard of 5 m/km. Series of velocity fluctuation occurred (0m/s – 2.81m/s) across the entire network during the simulation period. The existing network coverage is 70 % with 1360 households. The remodelled network, using EPAnet software for improved performance, was balanced with hydraulic parameters (pressure, velocity and head loss) meeting designed standards and peak hourly demand occurred at 18:00 hours across all the three (3) pressure zones.

A critical appraisal of selected water distribution networks was made under two modes of operation—intermittent water supply and continuous water supply. The study zones selected in four Indian cities—Ghaziabad, Jaipur, Nagpur, and Panaji—were typical residential areas with metered water supply and were readily amenable to hydraulic isolation from the rest of the area. The study areas included Lohia Nagar in Ghaziabad, Army Welfare Housing Officer's Colony in Jaipur, Shankar Nagar in Nagpur, and Mala Area in Panaji. Preparatory work in the study zones included updating water distribution network plans; installing valves and bulk meters wherever necessary to hydraulically isolate the zone from the rest of the area; and surveying homes to check for stopcocks and water meters and to collect information on household populations and consumers' opinions regarding water supply service. Both water supply modes were studied to collect data on per capita water consumption, pressures at various points in the distribution network, flow rate and variation and total flow into the network, nonrevenue water, water quality, and relevant information for engineering and socioeconomic analysis of the distribution network. Continuous water supply has certain advantages over intermittent water supply. There was an appreciable improvement in nodal pressures and flow patterns in the distribution networks and a decrease in peak factors. Also, microbial quality of the water improved considerably at the consumers' end. However, water consumption and nonrevenue water increased when the mode of supply was switched over from intermittent to continuous, which points to the need for preventive maintenance of distribution systems and proper metering at the consumers' end.

Water distribution systems are one of the critical infrastructures and major assets of the water utility in a nation. The infrastructure of the distribution systems consists of resources, treatment plants, reservoirs, distribution lines, and consumers. A sustainable water distribution network management has to take care of accessibility, quality, quantity, and reliability of water. As water is becoming a depleting resource for the coming decades, the regulation and accounting of the water in terms of the above four parameters is a critical task. There have been many efforts towards the establishment of a monitoring and controlling framework, capable of automating various stages of the water distribution processes. The current trending technologies such as Information and Communication Technologies (ICT), Internet of Things (IoT), and Artificial Intelligence (AI) have the potential to track this spatially varying network to collect, process, and analyze the water distribution network attributes and events. In this work, we investigate the role and scope of the IoT technologies in different stages of the water distribution systems. Our survey covers the state-of-the-art monitoring and control systems for the water distribution networks, and the status of IoT architectures for water distribution networks. We explore the existing water distribution systems, providing the necessary background information on the current status. This work also presents an IoT Architecture for Intelligent Water Networks - IoTA4IWNet, for real-time monitoring and control of water distribution networks. We believe that to build a robust water distribution network, these components need to be designed and implemented effectively.

The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO2-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September–November 2019) and dry (December 2019–February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R2 = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 μg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard (<1.0) of WHO’s Guideline Values (GVs).

Water losses in watersupply and distribution systems have been a serious problem in Turkey and allover the world causing economic costs and environmental drawbacks. Total waterlosses is the summation of real (physical) and apparent (commercial) losses. Mainactivities to reduce water losses include digitizing the components of network usingGeographical Information Systems (GIS), dividing large water distributionnetworks (WDNs) into District Metered Areas (DMAs), monitoring, carrying outyearly water balance, hydraulic modelling, pressure management, active leakagecontrol, recording water consumption of the users, reducing meter errors andillegal water consumption. The Ministry of Forestry and Water Affairs in Turkeyissued a new regulation for water losses reduction in 2014 based on the methodsused to determine and reduce the losses. This is followed by issuing practicaldescription of the technical procedure to reduce the losses in 2015. The newlegislation aims to reduce total water losses in all water authorities below 25%within certain time periods. All the water authorities are required to carryout yearly water balance and report them to the ministry together with forms tofollow up the efforts towards water losses reduction. In order to apply theprescribed techniques in a successful way, first of all water losses problemshould be understood well, technical and human resource capacity should beimproved, and sufficient financial resources should be allocated. Also, thewater utilities should have a strategic plan and a strong commitment to reducewater losses.

This study was aimed to optimize the designed water distribution system in the Wukro town using WaterGEMS model. The Darwin Designer in WaterGEMS was applied for finding optimal pipe diameter to supply adequate quantity of water at satisfactory pressures to the end users. In the WaterGEMS model, the Darwin Scheduler of daily pumping operations tools also used for optimal control and operation of pump systems. The WaterGEMS model was implemented in water distribution networks which include 117 pipes (40.67km), 99 demand nodes (equivalent to 50480 end users) that are spread across a hilly area over a 1989m to 2046m elevation gradient. The model was calibrated at the selected nodes within very good performance. The results have shown that the maximum pressure before optimization is 31.1m and after optimization increased to 38.1m, the minimum pressure on the former is 7.9m and 16m later during peak hour demand. Comparison of results showed that the optimized networks reduce the cost by 9.6% than those of before optimization networks by traditional hydraulic. In addition to this, the optimal tanks filling/emptying arrangement decreased the daily cost of energy consumptions by 12.5% compare as a currently scheduled pump. The finding of this study indicated that the WaterGEMS model is a promising approach for optimal sizing of pipes in design water distribution networks and pumping operational schedules. Keywords : Water Distribution Network, Genetic Algorithm, Pipe Diameter, Energy consumption, Darwin Designer, Darwin scheduler DOI: 10.7176/CER/12-6-01 Publication date: June 30 th 2020

Evaluation of Municipal Water Distribution System Reliability Using Minimum Cut-set Method

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 waterGEMSV8i, 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 (<0.6 m/s), 15.14 % for velocity range (0.6-2 m/s). Based on the simulated result, Reliability value 0.728 and 0.151, Vulnerability value 0.251 and 0.538 and Resiliency value 0.322 and 0.1 were obtained for both pressure and velocity respectively. The overall sustainability index was 0.375 but 0.19 for velocity and 0.559 for pressure. Therefore, sustainability of existing water supply and distribution system of Assosa town is not sustainable. It is mandatory to redesign the Assosa town water supply and distribution system in order to make it sustainable.

The drinking water network serving are up to 100 years old in Korea. Therefore, pipelines suffer various degrees of deterioration due to aggressive environments. Water supply system is one of the major urban infrastructures based on activities of mankind. Its most expensive facility is the water distribution network which is an important component in both quantitative and qualitative sides. Therefore, its effective maintenance and operation (M&O) has essential effect on sustaining human life. Moreover, factors of pipe deterioration and models to predict failure and optimal rehabilitation time are needed to support network management strategies. This study has performed to set up the determination of optimal rehabilitation time for Cast Iron Pipes (CIP) with diameter less than 300 mm. And the determination model for optimal rehabilitation time was developed by using cost analysis and deterioration evaluation on rehabilitation alternatives. In the result from the application of the field, the renovation time was faster about 10 years than the replacement time. Especially, as the difference between rehabilitation and replacement time on E-CIP was about from 3 to 5 years, and it was thought that the replacement was effective on E-CIP. To model sensitivity analysis, the discount rate of coefficient was fixed at 0.08, and the values of initial year break rate(N(t 0 )) and growth rate coefficient(A) were adjusted in values of 0.0009, 0.0018, 0.0027, and 0.05, 0.10, 0.15 respectively. When the values of N(t 0 ) and A was increased, the results from the time of rehabilitation and replacement was faster. It was thought that N(t 0 ), 0.018 was reliable values on the applied pipeline through the result of the study. In case of A, the values of A above 0.1 was thought to be proper.

Convex equations exist in different fields of research. As an example are the Hazen-Williams or Darcy-Weisbach head-loss formulas and chlorine decay in water supply systems. Pure linear programming (LP) cannot be directly applied to these equations and heuristic techniques must be used. This study presents a methodology for linearization of increasing or decreasing convex nonlinear equations and their incorporation into LP optimization models. The algorithm is demonstrated on the Hazen-Williams head-loss equation combined with a LP optimal operation water supply model. The Hazen-Williams equation is linearized between two points along the nonlinear flow curve. The first point is a fixed point optimally located in the expected flow domain according to maximum flow rate expected in the pipe (estimated through maximum flow velocities and pipe diameter). The second point is the calculated flow rate in the pipe resulting from the previous iteration step solution. In each iteration step, the linear coefficients are altered according to the previous step's flow rate result and the fixed point. The solution gradually converges closer to the nonlinear head-loss equation results. The iterative process stops once both an optimal solution is attained and a satisfactory approximation is received. The methodology is demonstrated using simple and complex example applications. DOI: 10.1061/(ASCE)WR.1943-5452.0000275. © 2013 American Society of Civil Engineers. CE Database subject headings: Optimization; Water distribution systems; Chlorine; Water supply. Author keywords: Convex; Optimization; Water distribution systems; Optimal operation; Successive linearization; Head loss.

Water Supply and Distribution Systems, Second edition is a comprehensive introduction to the topic of how water is delivered to homes and businesses throughout the world. It covers fundamental concepts and exploring the latest ideas of good practice. Water supply and distribution systems are a key element of essential urban infrastructure. Water utilities worldwide are embarking on a process of ‘digitalisation’, which promises to bring benefits to the industry, but this is fraught with uncertainty, hype, barriers to innovation and requires an organisational culture change. Water industry professionals have to address, not only classic design and management problems but also, increasingly, environmental and sustainability requirements and concerns. Drawing together information that is currently scattered across several sources, this book aims to alleviate the concerns engineers have with these issues. With chapters written by academics and practitioners this book covers Water Supply and Distribution Systems is a key text for early-stage practitioners, students in training to become water industry practitioners, and a useful reference book for practising engineers, particularly to provide up-to-date information on practices in today's increasingly complex water industry.

In this paper, a simplified methodology to increase the water distribution equity in existing intermittent water distribution systems (WDSs) is presented. The methodology assumes to install valves in the water distribution network with the objective to re-arrange the flow circulation, thus allowing an improved water distribution among the network users. Valve installation in the WDS is based on the use of algorithms of sequential addition (SA). Two optimization schemes based on SA were developed and tested. The first one allows identifying locations of gate valves in order to maximize the global distribution equity of the network, irrespectively of the local impact of the valves on the supply level of the single nodes. Conversely, the second scheme aims to maximize the global equity of the network by optimizing both location and setting (opening degree) of control valves, to include the impact of the new flow circulation on the supply level of each node. The two optimization schemes were applied to a case study network subject to water shortage conditions. The software EPA Storm Water Management Model (SWMM) was used for the simulations in the wake of previous successful applications for the analysis of intermittent water distribution systems. Results of the application of the SA algorithms were also compared with those from the literature and obtained by the use of the multi-objective Non-Dominated Sorted Genetic Algorithm II (NSGA II). The results show the high performance of SA algorithms in identifying optimal position and settings of the valves in the WDS. The comparison pointed out that SA algorithms are able to perform similarly to NSGA II and, at the same time, to reduce significantly the computational effort associated to the optimization process.

A Stochastic Programming Approach for the Strategic Valve Locations Problem in a Water Distribution System

As many water utilities are seeking new and innovative rehabilitation technologies to extend the life of their water distribution systems, information on the capabilities and applicability of new technologies is not always readily available from an independent source. The U.S. Environmental Protection Agency (EPA) developed an innovative technology demonstration program to meet this need. The purpose of the demonstration program is to evaluate rehabilitation technologies that have the potential to reduce costs and increase the effectiveness of the operation, maintenance, and renewal of aging water distribution and wastewater conveyance systems. This paper provides an impartial assessment of the effectiveness and cost of a cured-in-place pipe (CIPP) lining technology for water main rehabilitation. This project demonstrated an innovative Class IV rehabilitation technology that met the project requirements and as part of the evaluation, multiple utilities expressed their willingness to use the technology in the future. The demonstration provided valuable information on the design, installation, and QA/QC of CIPP used to rehabilitate water mains, and makes recommendations for continued improvements in the process used for internal reinstatement of services. One issue that requires more study is the effect of pre-rehabilitation cleaning process on the service connection reinstatement process. Other issues contributing to the need for external reinstatement that should be studied and improved upon include: flush service connections that cannot be identified in smaller diameter pipes and difficulty drilling service connections located in folds.

Modelling the impact of weather parameters on the microbial quality of water in distribution systems