There are direct relationships between leakage and consumption in the DISTRIBUTION NETWORK with the pressure. Due to the relationship between leakage and consumption with pressure, those can be reduced by the reduction of the pressure. One of the best and most cost-effective methods in order to reduce the leakage is pressure management. By installing pressure reducing valves, we can reduce the NETWORK pressure. In order to operate the pressure reducing valves better in the NETWORK, it is important to determine their optimum position and regulated pressure. In this research, we investigated the optimal position for installing pressure reducing valves in the WATER DISTRIBUTION NETWORK. The study is conducted by using a dynamic link between MATLAB and EPANET and a review of all possible states for installing pressure reducing valves. The research is considered as a multi-objective case. It was considered as a multi-objective case. The objective functions in this research are: minimizing the rate of leakage and consumption in the NETWORK, Minimizing the points with the pressure more than the tube's capacity and minimizing the number of nodes with a pressure lower than the standard rate. These analyzes were conducted over a 24-hour period. Based on the results, by installing three pressure reducing valves in optimal position and pressure-regulation from 40 m to 33 m in Birjand NETWORK, the average of consumption and leakage in 24 hours was reduced to 48. 24 liters per second, compared to the situation with the same number of pressers reducing valves were installed in different position. As it is derived from the results, this approach has a very high efficiency in reducing the leakage and consumption in the WATER DISTRIBUTION NETWORK.

Background and Objectives: Urban WATER DISTRIBUTION NETWORKs consider as one of the essential infrastructural facilities and equipment in urban areas. The pipes are one of the primary and essential components of a WATER DISTRIBUTION NETWORK break during operation due to various factors. So, developing models for pipes failure rate prediction can be one of the most crucial tools for managers and stakeholders to the optimal operation of the WATER DISTRIBUTION NETWORK. In the last decade, various studies have performed to predict the failure rate of WATER DISTRIBUTION pipes using statistical and soft models-each of which has strengths and weaknesses. This study aims to present a new approach based on the development of a hybrid prediction model, considering the capabilities of soft and statistical models, to more accurately predict the WATER DISTRIBUTION NETWORK pipes failure rate compared to statistical and soft models used in previous research. Materials and Methods: In order to achieve the study goals, 4-year (2015-2018) time duration statistics of Gorgan WATER DISTRIBUTION NETWORK characteristics including diameter, length, age, depth of installation, and the number of pipe failures used to predict future pipes failure rates. To predict the failure rate of WATER DISTRIBUTION NETWORK pipes, five different models, including three statistical models (linear regression, generalized linear regression, support vector regression) and two soft models (feed-forward neural NETWORK, and radial basis function neural NETWORK) has studied. Optimal parameters of the models were selected based on appropriate statistical error indicators, including correlation coefficient (R), Mean Square Error (MSE), and Correlation Mean square error Ratio (CMR) for the training and testing data. In order to select the best model from different models to predict the failure rate of NETWORK pipes, the values of R and MSE indicators of the above models were calculated in the validation stage and compared with each other. Finally, to predict pipes failure rate more accurately, a new approach is developed based on the hybrid prediction model in which the predicted values of pipe failure rates by statistical and soft computing models considered as independent variables of the best model inputs and the observed values of failure rates as dependent variables of the best model outputs. Results: Comparing the values of R and MSE indicators of each statistical and soft computing model used in this study in the validation phase show that these models cannot predict the pipes' failure rate with reasonable accuracy. Feedforward neural NETWORK model with the highest R = 0. 69 and the lowest MSE = 0. 062 values has the best estimates. Using the new approach developed based on hybrid soft and statistical models, the R index is equal to 0. 96, and the MSE index is equal to 0. 046. Conclusion: A significant increase in the R index (39%) and decrease in the MSE index (25%) through using the proposed hybrid approach compared to the feed-forward neural NETWORK model demonstrates that using the new approach provides perfect accuracy prediction of the pipes failure rate of the WATER DISTRIBUTION NETWORK.

IntroductionClimate change and population increase have caused an increase in consumption in the existing WATER DISTRIBUTION NETWORKs, as a result, an increase in the discharge in the pipes and a decrease in the pressure in the nodes. The decrease in pressure makes some consumers unable to receive the required WATER. To solve this problem, long-term and short-term solutions have been proposed. Replacing pipes with pipes with a larger diameter is one of the solutions. But it requires considerable time and money. Intermittent supply of WATER can be used in existing NETWORKs to solve the problem.TazeAbad NETWORK has a large pressure drop during peak hours. The reason for this is the low diameter of the main pipes, which cause a large drop in the pressure as the consumption increases and the discharge increases. In this study, in order to improve justice and increase WATER supply in this NETWORK, optimal intermittent supply of WATER was done for 6 areas of this NETWORK.MethodologyThe Intermittent supply of WATER is usually done based on pressure-based hydraulic analysis. In case, the consumers will also store the needs of other hours. In other words, the consumption pattern in continuous supply cannot be used for Intermittent supply. In this research, the Emitter method is used for the hydraulic analysis of the NETWORK. In this hydraulic analysis, the amount of WATER delivered to the node is a function of pressure.Intermittent supply for 6 areas of the WATER DISTRIBUTION NETWORK of TazeAbad city was optimized in 12, 8 and 6 hours with the aim of supplying the required WATER and high two-objective by using single-objective and two-objective Harmony Search algorithm. In the hydraulic model, the pressure-based hydraulic analysis method and the Emitter method were used to determine the discharge of the nodes and the results were compared. In different scenarios, the possibility of supplying WATER in 4, 3 and 2 time intervals was investigated.Results and discussionIn all scenarios, the results of pressure-based hydraulic analysis method are located in all areas of Tazehabad city during peak hours. In this method, despite the high DISTRIBUTION uniformity coefficient, the amount of WATER delivered to consumers is less than their needs in the hour of supply. At present, in TazeAbad DISTRIBUTION NETWORK, consumers receive more WATER at the existing pressures than the pressure-based method.In the Emitter method, in all scenarios, the DISTRIBUTION uniformity is lower than the pressure-based method. But in this method, the supply percentage is much higher. So that more than 95% of customers' demands have been met in 12-hour supply.By reducing the WATER supply time, the percentage of supply has decreased in both methods. In the single-objective algorithm, the ratio of supplied WATER to the required WATER is more than the double-objective algorithm. But the uniformity of the DISTRIBUTION has increased in the double-objective algorithm. In all scenarios, WATER delivery in the pressure-based method was in one time interval for all areas, but in the Emitter method, WATER was usually delivered in 2 time intervals.In TazeAbad NETWORK, if WATER is supplied in 2 shifts, the maximum discharge in the NETWORK is more than the maximum discharge of the existing conditions of the NETWORK. But if WATER is supplied in 3 and 4 time intervals, the maximum discharge will be closer to the maximum discharge of the NETWORK. The difference between the maximum and minimum NETWORK discharges in the two-objective algorithm was lower than the single-objective algorithm. The supply of WATER in 4 time intervals has had the least changes in discharge and consumption coefficients.Conclusions According to the scenarios reviewed in TazeAbad NETWORK, WATER supply in 8 hours was chosen as the best option. In this case, the ratio of supplied WATER to required WATER will be around 70% and the uniformity of DISTRIBUTION will be around 87%. The maximum discharge in the WATER DISTRIBUTION NETWORK is almost equal to the maximum discharge in the current conditions. Also, the range of discharge changes and consumption coefficients is lower than the current conditions. In other words, pressure changes in the NETWORK will be less than the current conditions.

One of the most sensitive and cost-intensive systems in urban WATER and wasteWATER companies is accident systems. Lack of a modem, accurate, and reliable burst management system at the present time results in great damages to consumers and to urban WATER and wasteWATER companies. Given the shortage of WATER and real loses in urban WATER DISTRIBUTION NETWORKs, burst modeling and management forms a necessary research area for WATER and wasteWATER companies. Improved efficiency of urban WATER supply and DISTRIBUTION system is the only possible way which cuts across innovative sciences and technologies. One such technology is the geospatial information system (GIS) that generates useful geospatial information and is used to perform spatial and hydraulic analyses that play an important role in urban WATER DISTRIBUTION NETWORKs. The purpose of this research is to study the fundamental concepts of establishing an accident management and modeling system in the Iranian urban WATER and wasteWATER companies using GIS. Systematic data storage, use of burst repair data, decreasing repair period, and determining real WATER losses, number of bursts, and required costs are of the advantages of this model. In this paper, a methodology is presented to gather and evaluate the burst data using the available spatial GIS analysis functions. Selecting a pilot area in Hamedan, accident information was gathered over a 6- month period. Several spatial and hydraulic analyses were performed and a number of indices were developed. The results showed that this NETWORK had a high break rate (13.58) which indicates poor infrastructure and management of the system. Furthermore, the main reason for pipe bursts was found to be poor hydraulic situation. It was concluded that applying this model which has been used in a real urban WATER DISTRIBUTION NETWORK increases the efficiency of the system and decreases the related burst costs.

Population growth and urbanization are the main reasons for increased pollution nowadays. Pollution entrance into urban drinking WATER DISTRIBUTION NETWORKs, can cause irreparable damage to human health as a result of the suction phenomenon. Awareness and understanding of pollutant sources and the process of contamination transport in the WATER NETWORK leads to advancements in the development of suitable modeling of this phenomenon, as well as, enabling proper crisis management, when the contaminants enter the NETWORK. In order to simulate the movement of nitrate in the soil, the nitrate advection-dispersion equation was programmed in MATLAB. The second zone of WATER DISTRIBUTION NETWORK of Zahedan has been considered as the study area and potential points with high concentration of pollutants in the NETWORK have been identified. NETWORK simulation, after two hours of contamination, was tested for WATER contamination by using EPANET software. To manage the NETWORK pollution crisis, two WATER quality management tools were used in the DISTRIBUTION NETWORK, including polluted WATER discharging and dilution flow, then their results were compared in the crisis management. The results of simulating the movement of pollutants in the soil demonstrated that nitrate concentration near the pipe is unallowable and greater than 50 mg/l. The results of discharging of the polluted WATER showed that by closing pipes from 1.1 to 1.3 of the pollution injection time and also discharging WATER from 5 to 8% of the base pipe flow can prevent the pollution from entering   other parts of the NETWORK. Moreover, For the first time, efficiency and positive performance of dilution flow as another tool for quality management of WATER DISTRIBUTION NETWORK was proved. The Required dilution flow to treat the quality of WATER was determined to be approximately 16% of the base pipe flow. In order to manage the pollution crisis in the WATER DISTRIBUTION NETWORK, it is vital to use these valuable tools in different situations.

The loss of drinking WATER from WATER DISTRIBUTION NETWORK is one of the problems of WATER and Sewage Companies worldwide, which reduces a remarkable part of the company's profit. Therefore, the aims of this research are: determination of strategies and their evaluating criteria for the loss management in WATER DISTRIBUTION NETWORK, prioritization of those strategies and criteria as well as selection of the most effective strategy. This study is a practical research and data gathering was performed via researcher-made questionnaires on snowball sampling based on the idea of 10 experts employed in WATER and Sewage Company of Isfahan province. Four strategies of WATER loss management of WATER DISTRIBUTION NETWORK assessed in questionnaires were selected based on the recommendations of International WATER Association, American WATER Works Association and the regulations of the non-revenue WATER committee by the deputy directorate and under supervision of the WATER and WasteWATER Company of Iran, 2020. Data gathering and analyzing were carried out using paired comparison matrix and analytic hierarchy process by the Expert-choice software. The calculated inconsistency ratio of questionnaires was determined to be 0.02, and therefore the most effective strategy of WATER loss management of Isfahan WATER DISTRIBUTION NETWORK was determined to be the pressure drop strategy with weight of 0.400. Three other strategies of active leak detection weight 0.259, NETWORK repair weight 0.175, and speed and quality of emergencies weight 0.167, were prioritized in the next ranks, respectively. Likewise, the criteria of financial supply weight 0.463 in the first rank, the criteria of technical supply weight 0.289 in the second rank, the criteria of training update weight 0.146 in the third rank, and the criteria of legal supply weight 0.102 in the fourth rank, were prioritized. By increasing the ratio of circular intubation in WATER DISTRIBUTION NETWORK and construction of WATER storage tanks in the northwestern heights of Isfahan, it is practical to develop the pressure drop strategy in flat districts of Isfahan city leading to the minimum WATER loss of Isfahan DISTRIBUTION NETWORK.

Detection of pollution in any WATER DISTRIBUTION NETWORK (WDN) is essential to maintain public health. Recent researches have demonstrated common WATER quality indicators (free Chlorine, pH, Electrical Conductivity, … ) response to contaminants, which can facilitate the pollutant detection in WDNs. In this research, EPANET-MSX model is used to simulate the realistic responses of common WATER quality parameters to a pollutant event in WDN, represented in example 3 of EPANET 2. 0. The aim of the study is to apply EPANET-MSX to trace Chlorine changes in response to the potassium cyanide injection order to optimize sensor placements WDN. Optimal sensor placement is derived based on coupled EPANET-MSX _ PSO (particle swarm optimization) framework. PSO is implemented as single and multi-objective algorithm. The objectives of the study are to reduce the pollutant detection time, increase detection likelihood, and reduce the contaminated WATER consumption as single and/or multi-objective problems. Studies on the sensor numbers, ranging from one to five, indicate 1-the pollutant detection time has decreased from 36. 22 to 17. 41 hours, 2-the pollutant detection likelihood has increased from 28. 8% to 68. 6%, and 3-the contaminated WATER consumption has decreased from 31. 87 to 3. 78 m3. The results show direct relationship between 1-pollutant detection likelihood and detection time, 2-pollutant detection likelihood and contaminated WATER consumptions, and 3-pollutant detection time and contaminated WATER consumption in multi-objective problems. Also, the location of the high-demand nodes in WDN and the contamination events occurrence can affect the location of the sensors.

A major part of the total cost of WATER supply systems is related to WATER transport and DISTRIBUTION systems. So, there have been many studies to enhance NETWORK planning. To plan WATER transport and DISTRIBUTION systems, the characteristics of the NETWORK (such as the diameter of the pipes, the height of the reservoirs, the type of pumps applied, etc. ) must be known. Then to analyze the NETWORK, this information is used as well as the rules that govern pipes and hydraulic systems. Using analysis and optimization, the most cost-effective and reliable design for the NETWORK can be chosen. In recent decades, many researches have been done regarding optimizing the design of WATER DISTRIBUTION NETWORKs. So, various optimization methods have been used to minimize the costs of these NETWORKs. An appropriate optimization method for the WATER supply NETWORK should be an efficient mathematical approach to optimize the objective function. In the models of hydraulic analysis of the NETWORKs, the actual values of the discharges can be determined based on the relationship between pressure and discharge in the nodes. But it should be considered that the issues such as discrete variables (allowable diameters), design constraints (minimum pressure or velocity, etc. ), and the complexity of the solving of hydraulic equations of NETWORKs, make it difficult to optimize. The optimization methods are only able to use the data given by the objective function and distance themselves from the complexities associated with the estimation of derivatives and other auxiliary functions. Since the pipes with the minimum cost should be within the allowable range in terms of pressure and velocity, another method is needed to solve the hydraulic NETWORK. Many researchers have been done to solve the problems of optimization of WATER transport and DISTRIBUTION systems, applying WATER DISTRIBUTION system modeling software such as EPANET. They define the objective function in ways which transmit the diameters to the EPANET software and return the hydraulic result of the pipes to the algorithm again. During this process, the EPANET software runes in terms of the evaluation of the objective function, and much time is spent on this process. But in the present study, using the Newton Raphson method, the hydraulic of the pipes was simulated in MATLAB. Thus, the problem solving time was greatly reduced because by the Newton Raphson method the diameters were accepted only if their speed and pressure were within the allowable range. In order to optimize, the combination of Big Bang Big Crunch (BB-BC) and Central Force Optimization (CFO) algorithm was applied. Each of these algorithms has the strengths and weaknesses that were adjusted and modified by combining them together and forming the BB-CFO algorithm. Despite high capabilities of CFO algorithm, it has weak points in acceleration calculation. The advantage of BB-BC is applying the best result in each replication and using inconstant parameters in the algorithm. But, the weaknesses of the two algorithms are such that they are completely complementary. In order to apply BB-CFO algorithm, the DISTRIBUTION NETWORKs of the Hanoi NETWORK and the Kadu NETWORK were selected to be optimized. After their hydraulic coding, the results were analyzed using the Newton-Raphson method with the BB-BC and BB-CFO algorithms. The Hanoi NETWORK is characterized by two loops and 34 pipes. After a 6360 evaluation of objective function, the Hanoi NETWORK was estimated at $ 6, 210, 780. As the last NETWORK increased difficulty of the problem, the Kadu NETWORK with two reservoirs, 34 pipes and 9 loops was selected. The method was able to reach Rs. 130, 645, 890 with 2288 evaluation of objective function. It should be noted that all pressures and velocities are within the allowable range and had better results compared with the power algorithms such as GA and PSO. Also, due to the lack of use of the software, the time of the program was less than other studies. The advantages of the proposed method in the current study were high speed, not applying hydraulic simulation software, use of inconstant parameters, and its simplicity in application. The present research showed that by understanding abilities and combining the capabilities of different algorithms, a better algorithm could be created. Also, the suggested algorithm could solve the problems more quickly without the use of hydraulic software and only by applying the rules which govern the hydraulic pipes.

Background: Trihalomethanes (THMs) are major group of chlorinated by products, potentially hazardous and carcinogenicity of these compounds was recognized. The purpose of this study was survey on THMs concentration in Ahvaz drinking WATER.Methods: A descriptive cross-sectional study was based on 36- week sampling program during the winter, spring and summer of 2011 in WATER DISTRIBUTION NETWORK of the No.1 and No.2 WATER treatment plants (WTP1 and WTP2) in Ahvaz city was conducted. Sampling in the DISTRIBUTION NETWORKs was taken from finished WATER and three points of DISTRIBUTION NETWORKs.THM species analyses carried out by gas chromatograph system (GC/mECD) with head space technique. SPSS software was used for data analysis. One-way ANOVA test was used for THMs average comparison between seasons and sampling point and T-test was used for comparison between two DISTRIBUTION NETWORKs.Results: In this study, the total THMs determined in winter, spring and summer ranged from 20.5-86mg/L, 18.92-66.06 mg/L and 17.35-174.75 mg/L respectively.Conclusion: According to this study, only in 6 samples the total THMs concentration exceed the U.S.EPA MCL (80 mg/L) and only in 3 samples exceed from the Iran standard and WHO guideline ( STHM/WHO guideline ≤1). Average values of the total THMs in summer were 1.4 and 1.6 times higher than winter and spring respectively. Furthermore, brominated THMs were dominant species.