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In uneven terrain regions, the water tank location plays a significant role in pressure distribution and economical pipe sizes in the water distribution system. This study aimed to determine suitable tank locations by the analytical hierarchy process (AHP) and geographical information system (GIS). Factors such as elevation, slope, population, land use land cover, and distance to the road are considered for this analysis. Thematic maps are created in ArcGIS and weights are determined using the AHP method. From the weighted overlay analysis, the result shows that 15.59, 52.36, 31.31, and 0.63% of the areas are suitable, moderately suitable, least suitable, and unsuitable, respectively. Since the area has an elevation range of 27-87 m, it is divided into three zones. An unsuitable location falls only under one zone; therefore, the results are tested in EPANET by locating the tanks in suitable and least suitable locations. Locating the tanks in suitable locations reduces the size of pipes economically and maintains the pressure successfully while locating the tanks in the least suitable locations creates a negative pressure and increases the pipe size. This study helps the designers to obtain an effective design of a water distribution network by evaluating suitable tank locations. [ABSTRACT FROM AUTHOR]

One of the major challenges faced by water companies around the world is the high level of chlorine losses in distribution networks. This paper presents an experimental study to examine chlorine loss in different types of pipe materials and select the ones with low chlorine demand for the rehabilitation of the water distribution network of San Pedro Nexapa, State of Mexico. The materials investigated include: polyvinyl chloride (PVC), galvanized steel (GS), polypropylene (PP) and high-density polyethylene (HDPE). A 24-h chlorine consumption study was performed in a simulated water distribution network to assess the impact of wall reaction coefficient on chlorine decay. Four sets of independent pipe loops of 50 mm in diameter and 12 m in length were used. Two different scenarios were considered based on different initial chlorine concentration (1.21 mg/L and 1.60 mg/L). Samples were collected at each loop at two-hour intervals and physicochemical analyses were conducted. Results from the experimental distribution network showed that the wall coefficient values for GS, HDPE, PP and PVC were 0.165 h-1, 0.059 h-1, 0.043 h-1 and 0.026 h-1, respectively. Experimental results showed that wall reaction coefficient values depend on initial chlorine concentration and the characteristics of pipe material. The rate of free chlorine decay was found to be faster in steel pipe and slower in the plastic pipes. Based on its having the lowest chlorine demand compared with the other pipes, PVC pipe would be selected to rehabilitate Nexapa water distribution network, State of Mexico. The wall coefficients from the experimental study were incorporated into EPANET through four simulation runs to predict chorine decay of San Pedro Nexapa water distribution network, State of Mexico. In the PVC and PP pipes higher residual chlorine concentrations were observed that ranged from 0.30 to 0.90 mg/L and 0.50 to 0.95 mg/L, respectively. This study is important for utilities to operate their system effectively and protect public health. [ABSTRACT FROM AUTHOR]

In the present work, a model is presented for the optimization of water distribution networks (WDN). The developed model can be used to verify node pressures, head losses, and fluid flow rate and velocity in each pipe. The algorithm is based on particle swarm optimization (PSO), considering real and discrete variables and avoiding premature convergence to local optima using objective function penalization. The model yields the minimum cost of the network, the node pressures and the velocities in the pipes. The pressures and velocities are calculated using the hydraulic simulator Epanet. Some benchmark problems are used to test the applicability of the developed model, considering WDN for small-, medium-, and large-scale problems. Obtained results are consistent with those found in the literature. [ABSTRACT FROM AUTHOR]

Due to the economic crisis and water scarcity happening in recent years, many researchers have focused on the water distribution network optimization problem. On this specified subject, all recent research has applied stochastic meta-heuristic algorithms to solve these sets of problems. In this study, the application of a novel deterministic physically inspired heuristic algorithm for minimizing the cost of pipe-sizing in the water distribution system (WDS) is investigated. In fact, the algorithm used in this research is the modified central force optimization algorithm to solve the water distribution network problem called CFOnet. The approach is applied to optimize the design of the Kadu and Khorramshahr networks. For this purpose, CFOnet method is programmed in MATLAB and interfaced with the hydraulic simulation model, EPANET. The obtained solutions in this study are compared with those stochastic methods in the WDS optimization literature. This comparison shows that CFOnet is more efficient in obtaining lower cost than other optimization methods for solving the two mentioned WDSs, while it enjoys the merits of a deterministic optimization method. [ABSTRACT FROM AUTHOR]

A simple graphical tool was developed, that finds the optimal combination of pumps and their rotational speeds for all possible working points for a pump battery. The tool was integrated into EPANET as well as EPA SWMM simulation packages. The tool allows us to analyse and optimize operation non-identical parallel pumps with different minimum and maximum frequencies for all possible working points. Pump characteristics and efficiency curves can be given in tabular format or as analytical functions of flow. Degradation of pump efficiency at lower rotational speed is taken into account, as well as motor and variable speed drive efficiencies at partial loads. The optimal solution provided by the tool was compared to measurements in two case studies. Our case studies showed 6.1-8.5% reduction in energy usage using the optimal parallel pumping control strategy compared to the currently used strategy, where all running pumps have the same frequency. [ABSTRACT FROM AUTHOR]

The need for accurately predicting water quality through models has increasingly been crucial in meeting rigorous standards and customer expectations. There are several endeavours on developing robust water quality models for water distribution systems. In this paper, two variants of the EPANET 2 water quality model have been assessed to inform future research. The models are the multiple species extension EPANET-MSX and the pressure-dependent extension EPANET-PDX. Water quality analysis was conducted on a hypothetical network considering various operating pressure conditions. Different kinetic models were employed to simulate water quality. First order, limited first order and zero order models were used for predicting chlorine residual, disinfection by-products (DBPs) and water age respectively. Generally, EPANET-MSX and EPANET-PDX provided identical water quality results for normal operating conditions with adequate pressure but different results for pressure-deficient networks. Also, a parallel first order model with fast and slow reacting components was used for chlorine decay and DBPs using the EPANET-MSX model for a network operating under normal pressure conditions. [ABSTRACT FROM AUTHOR]

This paper focuses on the generation of synthetic models of water distribution networks (WDN). Models are widely used in many fields related with WDN planning and operation. Therefore, the main contribution of this work is to provide an automatic procedure to build models with the well-known EPANET tool in a manner that, with a small amount of input data and a few clicks, the user can build a network topology and assign suitable pipe diameters. For that purpose, a new application, called WaterNetGen, was designed and implemented as an extension to the EPANET software. WaterNetGen can be used to generate synthetic models of WDN, with several hundred nodes and pipes, within a few minutes. The sizing capability allows the selection of commercial diameters, such that the final network design satisfies certain user-defined design constraints, like minimum diameter, maximum velocity and minimum pressure. The total water demand is allocated to the pipes taking into account their length and a demand coefficient. The water demand of each pipe is then assigned to its start and end nodes and follows a specific demand pattern [ABSTRACT FROM AUTHOR]

Losses of water due to leakage occur in every distribution network, the only difference is in the amount of leakage. The leakage levels are relatively high in cities of developing Asian countries. Among the several factors, operating pressure is the most important affecting the leakage. This paper describes how the management of pressure can help reduce the leakage in the water distribution network. EPANET is used to develop the hydraulic model to analyse the effect of alternative pressure profiles on the leakage in a pilot area within the water distribution system of Bangkok. One of the alternatives is implemented in the field to verify the applicability of the model. Results indicate that the average reduction in pressure by 2.4 m can reduce the leakage by 12.5% of the system inflow without compromising the level of service. [ABSTRACT FROM AUTHOR]