جستجوی مقالات مرتبط با کلیدواژه « water distribution networks » در نشریات گروه « مهندسی آب »

An interesting procedure to evaluate the system management policies, including water distribution networks, is to use performance indicators, referring to parameters governing the system performance, including field monitoring, how it works, operation status (Kliseh et al., 2018). In general, two indicators of reliability and resilience are considered in the operation of the water distribution network in urban and rural areas. Hydraulic reliability refers to the continuous supply of a certain amount of water with the required pressures at the desired time and place (Mazaherizadeh et al., 2019) and resilience as the ability of a system or community to survive, absorb and adapt to risk and to protect yourself from the effects of hazards is defined as quickly and efficiently as possible (UNISDR, 2018).Resilience index has been applied to assess the hydraulic needs of the network (Pandit et al., 2012), to evaluate the urban water network infrastructure against earthquakes (Alavi et al., 2018), to optimize the network Water distribution (Reca et al., 2017; Mazaherizadeh et al., 2019), and simultaneous pipe failure assumptions (Gheisi and Naser, 2014; Atashi et al., 2020).In this study, the efficiency of the distribution network in the case of integrating several reservoirs and discrete was investigated and compared using the Resilience index. The distribution network was analyzed based on two scenarios: 1) sufficient flow in the network and 2) essential reversibility of the system.

The water distribution network of Surat, India, with a resilience index of 0.396, can supply water to only 56% of its population (Popawala & Shah, 2011). The area covered by six reservoirs (‎Fig. 1) was selected to evaluate the city's water distribution network. The resilience index of the distribution network was calculated for both cases of the connected and discrete reservoirs. In the current situation, the reservoirs are connected through transmission lines, and the maximum water level of all reservoirs is the same. ‎Fig. 2 shows the hourly fluctuations of consumption patterns.WaterGEMS software, an upgraded version of WaterCAD software, was used for modeling. This software evaluates the water supply network based on hydraulic conditions and examines the pressure and flow velocity at the node points. This software has more flexibility than other software and also provides the possibility of interacting with other software.To build the model, first, the physic of the distribution network was simulated and the nodal elevations and consumption amounts were allocated. According to the reservoir output pattern and maximum daily and hourly coefficient, consumer consumption pattern was calculated based on the output flow analysis and assigned to the nodes related to each reservoir. Finally, the hydraulic model of the grid was dynamically fabricated for maximum daily consumption, and calibrated for points with very high or shallow pressures over four months at different time intervals.

‎Fig. 3 shows the outlet pressure ranges of the hydraulic model. In the case of maximum consumption, it changes from 26 to 60 meters in most cases in the current situation. Ten percent of water distribution network nodes in the study area have pressures below 26 meters and more than 60 meters. The most important reason for the equilibrium pressure of the site is the reservoirs connection and the integrity of the water distribution network system throughout the area under study. Also, a minimal number of nodes in the minimum consumption state have pressure above 60 meters affected by night patterns for pressure breakers in the study area.‎Table 2 shows the pressure in the water distribution network in the state of maximum consumption in integrated and discrete tanks. The rate of nodes with hydraulic pressure in the defined range in the case of connected tanks is higher than that of unconnected tanks.‎Table 3 represents the network resilience index (SI), the number of points outside the desired pressure range (26 to 60 meters of water pressure) during peak hours and minimum consumption, and the ratio of this number of points to all points. The resilience index of the network in the state of integrated reservoirs (0.87) is higher than the state of non-interconnection (0.79) because happening a failure, the interconnected reservoirs help adjacent areas in the matter of water supply. In general, the status of the network is considered acceptable.

A continuous and separate hydraulic model of the study water distribution network was prepared. The results show that the integration of adjacent reservoirs has a positive effect on improving the resilience of the distribution network; in other words, at different times of the day and night, depending on the volume of the tank and the consumption pattern of the connected tanks, it helps to supply water to the adjacent related areas. Due to the complexity of connecting distribution network lines in neighboring regions and the change of consumption pattern at different hours, the degree of dependence of nodes to the relevant reservoir varies during the day and night.

As the main component of real water losses, leakage afflicts most water networks worldwide; even the best Water Distribution Networks (WDNs) have leakage in their network infrastructure. Several methods and strategies have been developed for leakage reduction and performance improvement in WDNs. In practice, leakage control strategies, including active leakage control, passive leakage control, pressure management, and infrastructure asset management, are performed by water utilities to reduce leakage. The main question is, which of these leakage management strategies are the most appropriate for a specific WDN? The answer to this question is obtained by analyzing the economic level of leakage (ELL). In fact, the essential component of a leakage control strategy is that its target is set in terms of the economic level of leakage (ELL). This paper provides a comprehensive review of the estimation of the ELL at different time frames, including short-run, long-run, and sustainable in WDNs. In addition, a procedure to estimate the ELL is proposed according to the conditions in each network or the relevant water utilities. Results of this review could be a valuable reference resource for practitioners and researchers dealing with non-revenue water in WDNs.

The friction factor of pipes in water distribution networks is different from the laboratory values due to the connections, installation method and created bights. Passing of time, erosion and sedimentation in pipes are also factors affecting roughness. Therefore, the roughness of pipes should be calibrated during network modeling. In this research, a new optimization method, called sensitivity analysis method was introduced for roughness calibration. In this method, first the pipes are grouped based on the material and diameter of pipes. Then, using sensitivity analysis it is determined what the effect of changing the roughness of different groups on node pressures is. In the following, roughness calibration is performed according to the importance of the groups respectively. This method was investigated on a real network with assumed changes. In order to compare the efficiency of the present method, the results obtained were compared with the results obtained from the calibration tool of WaterGEMS software. Fitness that is obtained by present study method and output of WaterGEMS in studied network are 0.02 and 8.11 centimeters, respectively. Obtained results show the high ability of this method in pipes network roughness calibration.

Contamination of drinking water is known as a major threat of water security around the world. As contamination enters a water distribution network, it spreads rapidly into the network and poses health and safety risks to the community. Using a set of sensors to report the concentration of chlorine or any other chemical, useful observations can be made to detect, identify and manage pollution. Based on these observations, location, concentration and start time of contamination can be determined and decision makers can be informed. In this paper, a simulation-optimization approach is used to solve the problem of contamination source characterization in which the EPANET software is used as a simulator and the Genetic Algorithm is used as an optimizer. The model developed in this paper is implemented on EPANET example 3. Modeling of water distribution networks uses information as input data which can cause error in model simulation. Pipe roughness and chlorine deterioration rate are among these inputs. The model has been implemented to find the location, start time and concentration of inlet pollution and the effect of pipe roughness and chlorine deterioration rate on the model responses have been investigated. The pollution entry scenario is applied to the network and the model presented is accurate in finding the location and time of the contamination. As the variables increase, the model accurately estimates the location and time of entry of the contamination but does not have complete accuracy in estimating the concentration of contamination, which is calculated with standard deviation of σ = 4.8% -8.1%.

Contamination of a water distribution network (WDN) is one of the most dangerous events which may occur in accidental or deliberate conditions. The contamination spreads across the network based on the water flow and, as a result, has negative consequences on public health. In this regard, one of the most effective strategies is to install quality sensors. These sensors could reduce the damage due to detecting the contamination and applying appropriate policies. In this study, an optimization approach for quality sensor placement is presented. In this model, based on spatial and temporal uncertainty of input contaminant, a new parameter called maximum possible damage is introduced. Using EPANET as a hydraulic and quality simulator, the damage matrices are calculated for all possible values of temporal and spatial input contamination. In the following, these matrices are used in an optimization model in order to calculate the maximum possible damage. The genetic algorithm is implemented here to solve the problem.  The presented method is investigated on a case study network, and results show that this method could find the optimal sensor placement and reduce the damage caused by contamination. As an example, it can be seen that installing one or two sensors could reduce the contaminated water damage by 56% and 78%, respectively.

Reliability is one of the important parameters in the process of design and operation of water distribution networks. Reliability index refers to the ability of the water distribution network to supply water with standard quality, sufficient quantity and within the appropriate pressure range for consumers under normal and abnormal operating conditions. Although many indicators have been provided by various researchers to evaluate the reliability of water distribution networks, so far this issue has not been taken into consideration by consulting engineers and water and wastewater companies in the design and operation of real water distribution networks. In this study, after preparing a calibrated hydraulic model for water distribution network of Oshnaviyeh city in West Azarbaijan province, the reliability of the mentioned network was evaluated. According to the results, the average reliability index of the water distribution network of Oshnaviyeh city during the day is 38.3, which means stressful operating condition. Examination of the reasons for the low reliability led to the identification of weaknesses of this network such as inappropriate diameter of some pipes, weakness in implementing pressure management program, inappropriate status of pipe loops and high amount of leakage (about 52 l/s). Improving the reliability of the studied water distribution network requires the implementation of rehabilitation and renovation programs based on the suggestions proposed in this paper. The results of this study showed that by evaluating the reliability of water distribution networks, existing weaknesses would be identified and their serviceability level would be improved and customer satisfaction would be increased.

One of the main responsibilities of water and wastewater companies in the field of operating of water distribution networks (WDNs) is the management and control of leakage from these networks. In this regard, active leakage control (ALC) is one of the main strategies in reducing leakage and achieving economic level of leakage (ELL). In this paper, a practical methodology was developed to determine the ELL which is included the steps determining the points of pressure and flow rate measurements, collecting of required field data and cost data, the estimation of leakage level in the network and the determination of the ELL of the network based on the ALC strategy. Economic performance indicators such as the economic leakage index (ELI) and the economic network efficiency (ENE) are also obtained using the determined ELL. The developed methodology was applied for a district of the WDN of Mashhad. The results showed that the ELL in the study area is 27.5 m3/connection/year. While the current level of leakage was estimated to be around 49.2 m3/connection/year, based on the minimum night flow (MNF) analysis. Moreover, the ELI and ENE were calculated 1.79 and 56% respectively. The developed methodology in this paper can assist practitioners and managers of water and wastewater companies for target-setting of the level of leakage and determining of the ELL based on it.

Water distribution networks (WDNs) are complicated infrastructures which their construction, operation and maintenance have considerable costs. Since most of the variables effective on the design and operation of WDNs cannot be computed and achieved accurately and definitely, uncertainty subject should be considered as an inseparable issue in the calculation of these networks. In this study, using the fuzzy logic concept and genetic optimization algorithm, the impact of uncertainties of input variables (nodal demands and pipe roughness coefficients) on the results of hydraulic analysis of two sample networks have been examined. In this regard, first, the fuzzy membership functions of input variables have been determined and by considering the simultaneous impacts of these variables' uncertainties, the output variables of hydraulic analysis have been calculated more accurately. Afterwards, variables of pressure, velocity and energy loss have been considered as representers for evaluating the hydraulic performance of network elements (nodal demand and pipes). In order to calculate the hydraulic performance indices of these elements, after analyzing the network based on the pressure driven simulation method, penalty curves defined according to the available standards, have been employed and the obtained results have been compared to the results of the demand driven simulation method. In addition, a new relation for combining the performance indices of network elements and obtaining an index for evaluating the total pipe performance and calculating the total hydraulic performance index of network has been introduced. According to the obtained results, slight uncertainties in the input variables of hydraulic analysis lead to high uncertainties in the outputs of the hydraulic analysis of WDNs. Meanwhile, velocity in pipes more than nodal pressures are affected by the uncertainties of input variables of hydraulic analysis. Also, implementing the pressure driven simulation method in performance evaluation of WDNs in their operation period leads to more reasonable and real results. For instance the total performance of network was 0.56 for 9-loop network and was 0.26 and 0.59 for 2-loop network, respectively, based on demand and pressure driven simulation methods.

Pipes failure events in the water distribution networks provide leakage of water. Failures cause the loss of significant fresh water and investments losses. The most important parameters are: material, age, length, diameter and hydraulic pressure. In this paper four statistical methods have used for analyzing pipe incidents, with the goal of estimation of failure probability in future, with finding the most influences parameters in the incidents. The statistical regression models using in this research are linear regression model, exponential regression model, Poisson regression model , and Logistic regression model . For evaluation of the models, the data of a pilot in the first district of the Tehran’s Water and Wastewater Company with more than 48500 consumers, total pipe length of 582702 meter, different materials and diameters were used. The results demonstrated that the logistic model has a better performance than others to predict the future events with a higher probability.

Todays, in addition to the optimal hydraulic design of water distribution networks, the optimization of energy consumption in pumping station is more important for researchers. Due to the energy costs include the major part of operation cost at a water network, in this paper study the optimization of daily energy cost of pumping station with five parallel pumps, using by Darwing scheduler module at WaterGEMS V8i software based on Simple Genetic Algorithm (SGA) and Fast Messy Genetic Algorithm (FMGA). The hydraulic constraints include the minimum pressure and maximum pressure of junctions, maximum velocity of pipes and maximum number of economic off and on of pumps. The results showed that the energy costs reduced 15 and 10 percent using by Simple Genetic Algorithm (SGA) and Fast Messy Genetic Algorithm (FMGA), respectively, with regard to electricity tariffs in To optimize the performance was achieved without pumps.so we achive 10 and15persent reduce energy cost.

Recent years have witnessed a growing interest in the optimal operation of water distribution networks (WDNs) as a result of their enhanced quality and reliability with due regard for the economic limitations faced. For this purpose, the present study was designed and implemeted to realize the two objectives of minimizing disinfection costs and maximizing reliability of water quality in water distribution networks using the multi-objective form of ACO algorithm as the optimization method. Different system analysis methods based on DDSM (demand driven simulation method) and HDSM (head driven simulation method) were also employed to investigate and compare the effects of constant versus time-dependent chlorine injection and pump speed. Results indicated that, compared to the condition with constant parameters of chlorine injectuion and pump speed, great improvements could be achieved in enhancing the reliability of water quality and reducing disinfection costs by using variable speed pumps (vsp) and time-dependent chlorine injection regimes without the need for buster pumps. Comparison of the analytical methods employed also indicated that application of HDSM led to reduced chlorine injection costs and improved reliability of water quality.

The water quality in distribution networks is regularly monitored on a routine basis. However, the quality of water in pipes and tanks inside buildings is rarely ever inspected. This study investigated the overnight stagnation of drinking water in household taps and building tanks. For the purposes of this study, the Heterotrophic Plate Counts test was conducted for which water samples were taken from 25 different buildings located in different parts of Tehran, among which 11 buildings had water storage tanks. The results showed a considerable increase in bacterial concentrations in all the water samples after stagnation. The results of bacterial enumeration in water tanks indicated that although building tanks reduced the quality of the stored water, bacterial concentrations in water tanks were still below the standard limit.

Leakage is one of the most serious problems in water distribution networks. Limited resources of water and the increasing expenses of transport, treatment, pumping, storage and distribution of water, notify the importance of leakage reduction. Due to the direct relation between leakage and pressure, pressure management is a useful and cost effective method for leakage reduction. In this research pressure reducing valves are used to achieve this goal. An optimization procedure is applied to minimize the difference between the available head and minimum standard head at each node. Sum of square differences between the available and minimum standard heads at each node are minimized using linear and non linear programming. To analyze the hydraulic conditions of the system the head driven simulation method is used. In this method the available nodal outflows are not fixed and vary with nodal pressure fluctuations. Finally a test network, have been used to illustrate the validation of the proposed method. The results of this procedure define the PRV’s outlet values. Based on these optimized values, nodal heads tend to be very close to the minimum standard values which lead to the maximum leak reduction.

In this paper different methods for analysis of pipes breakage in urban water distribution networks are investigated. At first, it is necessary to obtain complete and exact information about the failures in the networks. Thus, a suitable form was designed for gathering the required information including all the necessary parameters for the analysis. Then the rates of annual pipe failures were assessed based on the diameter, age and availability of pipes. Mechanical reliability (availability) of network components is the probability that component is performing well in the networks during its lifetime. The results show that the rate of breakage is decreased by increasing the diameter in all pipe types (e.g. Steel, Asbestos Cement). Assessing the availability of the pipes according to their diameter and length reveals an increase in availability by increasing the diameter but a decrease in availability by increasing the length of the pipes. It is also seen that the rate of water loss decreases by increasing the diameter of pipes. Furthermore, an increase in the rate of failures is observed when pipes are aging. The results of pipe breakage analyzed. Introduced in this paper provide helpful information to be used in design, operation and rehabilitation of pipe networks.