Water Distribution Network Simulation Research Articles

Study on Large-Scale Urban Water Distribution Network Computation Method Based on a GPU Framework

Large-scale urban water distribution network simulation plays a critical role in the construction, monitoring, and maintenance of urban water distribution systems. However, during the simulation process, matrix inversion calculations generate a large amount of computational data and consume significant amounts of time, posing challenges for practical applications. To address this issue, this paper proposes a parallel gradient calculation algorithm based on GPU hardware and the CUDA Toolkit library and compares it with the EPANET model and a model based on CPU hardware and the Armadillo library. The results show that the GPU-based model not only achieves a precision level very close to the EPANET model, reaching 99% accuracy, but also significantly outperforms the CPU-based model. Furthermore, during the simulation, the GPU architecture is able to efficiently handle large-scale data and achieve faster convergence, significantly reducing the overall simulation time. Particularly in handling larger-scale water distribution networks, the GPU architecture can improve computational efficiency by up to 13 times. Further analysis reveals that different GPU models exhibit significant differences in computational efficiency, with memory capacity being a key factor affecting performance. GPU devices with larger memory capacity demonstrate higher computational efficiency when processing large-scale water distribution networks. This study demonstrates the advantages of GPU acceleration technology in the simulation of large-scale urban water distribution networks and provides important theoretical and technical support for practical applications in this field. By carefully selecting and configuring GPU devices, the computational efficiency of large-scale water distribution networks can be significantly improved, providing more efficient solutions for future urban water resource management and planning.

Optimizing the water distribution network of community water supply using different computer simulation techniques

The appropriate operation of a water distribution network (WDN) of any water supply scheme is vital to supply sufficient potable water to consumers at sufficient pressure. However, the performance of the WDN may vary from the original design in the long run. In this study, a WDN network model was built using WaterGEMS and WaterCAD computer simulators, and hydraulic analyses were conducted to obtain an optimal WDN for a community water supply scheme of a village in Sri Lanka. A series of steps such as; selection of models, network representation, simulation of network, problem identification, network configuration finalization, and results analysis were carried out in developing the WDN simulation model. The hydraulic parameters such as pressure, flow velocity, and flow rate were analyzed under extended period simulation. The result indicated that the nodal pressure head in the junctions (100%) is above the required pressure level of 10 meters H2O, which is adequate for the effective performance of the water distribution system (WDS) during peak and off-peak demand hours. The elevated water tower was optimized with a 10 m height to supply water at satisfactory pressure. Nodal pressure is negatively correlated with ground elevation. The flow velocity was observed within the range of 0.1-0.4 m/s in 67% of the pipe network, while 17% of the pipe network velocity was below 0.1 m/s. The low daily water demand of the small community could be the reason for the low-velocity scenario, which shall lead to silt deposition in the pipelines; hence frequent line washout to eliminate the silt deposition in the system is recommended. The WDN was designed for optimized pipe sizes with availability in the market.

Dealing with Zero Flows in the Simulation of Water Distribution Networks with Low-Resistance Pipes Using the Global Gradient Algorithm

Dealing with Zero Flows in the Simulation of Water Distribution Networks with Low-Resistance Pipes Using the Global Gradient Algorithm

Utilizing Matrix Completion for Simulation and Optimization of Water Distribution Networks

Simulation of water distribution networks (WDNs) constitutes a key element for the planning and management of water supply systems. The literature presents different formulations of heads-flows equations that differ in terms of dimensionality, computational cost, and solution accuracy. Whereas this problem has been the subject of active research in the past, in the last decades a state of stagnation was reached and no new formulations were introduced. In this study, we propose a novel formulation that utilizes a matrix completion technique to construct a reduced-size nonlinear system of equations that guarantees both mass and energy conservation. The advantages of the proposed method are demonstrated in simulation and optimization settings. In the former, the method demonstrates improved scalability and accuracy as compared with other widely known formulations. In the latter, the new formulation leads to compact optimization problems that result in better performance in terms of the objective function, run time, and rate of successful optimization runs.

Discussion of “Dynamic Pressure-Dependent Simulation of Water Distribution Networks Considering Volume-Driven Demands Based on Noniterative Application of EPANET 2” by P. Sivakumar, Nikolai B. Gorev, Tiku T. Tanyimboh, Inna F. Kodzhespirova, C. R. Suribabu, and T. R. Neelakantan

Discussion of “Dynamic Pressure-Dependent Simulation of Water Distribution Networks Considering Volume-Driven Demands Based on Noniterative Application of EPANET 2” by P. Sivakumar, Nikolai B. Gorev, Tiku T. Tanyimboh, Inna F. Kodzhespirova, C. R. Suribabu, and T. R. Neelakantan

Closure to “Dynamic Pressure-Dependent Simulation of Water Distribution Networks Considering Volume-Driven Demands Based on Noniterative Application of EPANET 2” by P. Sivakumar, Nikolai B. Gorev, Tiku T. Tanyimboh, Inna F. Kodzhespirova, C. R. Suribabu, and T. R. Neelakantan

Closure to “Dynamic Pressure-Dependent Simulation of Water Distribution Networks Considering Volume-Driven Demands Based on Noniterative Application of EPANET 2” by P. Sivakumar, Nikolai B. Gorev, Tiku T. Tanyimboh, Inna F. Kodzhespirova, C. R. Suribabu, and T. R. Neelakantan

Self-Adaptive Cuckoo Search Algorithm for Optimal Design of Water Distribution Systems

Self-adaptive cuckoo search algorithm is used to optimize the design of water distribution system problems. It is proposed to dynamically adjust the two sensitive parameters of the algorithm, (i) step size control parameter ‘α’ and (ii) discovering probability parameter ‘Pa’ which largely govern the exploration and exploitation search strategies of the algorithm. These parameters are essential for enhancing the performance of the algorithm and normally the values of these parameters needs careful selection according to the type of problem. Single objective self-adaptive cuckoo search algorithm (SACSA) and multi-objective self-adaptive cuckoo search algorithm (SAMOSCA) are proposed in this study. Robustness and efficiency of these algorithms in single (minimization of cost) and multi-objective scenarios (minimization of cost and maximization of resilience) is validated using standard water distribution benchmark problems i.e. Two loop and Hanoi network. These are later applied to solve a medium size real-life water distribution system located at Pamapur, Telangana, India. A simulation-optimization based program combining the water distribution network simulation software EPANET 2.2 and MATLAB is used for computation. The proposed methodology has provided better results in terms of computational efficiency as well as found better solutions when compared to the previously reported results in both single and multi-objective scenarios. In the case of multi-objective problems, it has been observed that SAMOCSA has been able to find new points in pareto front when compared to the best-known pareto front reported in the literature. Self-adaptive cuckoo search algorithm has been found to be an attractive alternative in both exploration and exploitation of larger search spaces for finding better optimal solutions.

Optimising water distribution systems using a weighted penalty in a genetic algorithm

Genetic algorithms (GAs) have become the preferred water system design optimisation technique for many researchers and practitioners. The main reason for using GAs is their ability to deal with nonlinear complex optimisation problems. The optimal decision in terms of designing, expansion / extending, addition or rehabilitation of water supply systems has to review possible options and select a cost-effective and efficient solution. This paper presents a new approach in determining a penalty value depending on the degree of failure, of the set pressure criteria, and the importance of the link supplying a specific node. Further modifications are also made in the cross-over and mutation procedures to ensure an increase in algorithm convergence. EPANET, a widely used water distribution network simulation model, is used in conjunction with the proposed newly developed GA for the optimisation of water distribution systems. The developed GA procedure has been incorporated in a software package called GANEO, which can be used to design new networks, analyse existing networks and prioritise improvements on existing networks. The developed GA has been tested on several international benchmark problems and has proved to be very efficient and robust. The EPANET hydraulic modelling software as well as the developed GANEO software, which performs the optimisation of the water distribution network, is freeware. The software provides a tool for consulting engineers to optimise the design or rehabilitation of a water distribution network.

Efficient Modeling of Active Control Valves in Water Distribution Systems Using the Loop Method

AbstractThis paper presents a novel approach to model pressure- and flow-regulating devices in the context of the Newton-Raphson loop method for water distribution network simulation. The proposed ...

Comparison of Pressure-Driven Formulations for WDN Simulation

This paper presents the comparison of five pressure-driven formulations in the context of water distribution network (WDN) modelling. These formulations, which relate nodal outflow q to users to demands d and nodal pressure heads h, were implemented inside the global gradient algorithm for the snapshot solution of the equations concerning mass and energy conservation at WDN nodes and pipes, respectively. The modelling of leakage nodal outflows as a function of pressure was also considered. The applications concerned two case studies, in which nodal demands were suitably amplified to lower service pressure below the desired values. This was done to stress the effects of the pressure-driven dependence q(h) in the WDN. The results showed that the formulations tend to behave similarly in terms of nodal outflows. Compared to a widely used formulation, which features a q(h) relationship with derivative discontinuities, the other four formulations analyzed tend to guarantee faster algorithm convergence, above all for simple and poorly interconnected WDNs, due to their smooth q(h) relationship. The results in terms of nodal pressure heads can be very different, above all for low values of h.

Method for Extended Period Simulation of Water Distribution Networks with Pressure Driven Demands

This paper proposes a non-iterative method to perform the simulation of water distribution systems with pressure driven demands using EPANET2 without the need to use its programmer’s toolkit. The method works for single period simulation (snapshot) and for extended period simulation (EPS) as well. It is based on the addition of a flow control valve (FCV), a throttle control valve (TCV), a check valve (CV) and a reservoir to each demand node in the network, in addition to a list of simple controls to modify the setting of the FCV and TCV in each time step. The main advantages of this approach are: 1. the source code of EPANET2 is not modified, 2. the toolkit functions are not needed for the simulation and they remain available for further uses, 3. the extended period simulation (EPS) is performed by EPANET2 and it carries tank levels, demand variation and other time-changing variables internally. The performance of the method is tested in two benchmark networks and a real size network with pumps, tanks and a 24 h demand pattern. The results show that the method computed the pressures and outflows accurately and that the computational time required is not significantly higher than a demand driven execution in most cases.

Development of a software tool for teaching real‐time state simulation of water distribution networks

AbstractAn educational software tool was developed for teaching the real‐time state simulation of water distribution networks (WDNs) to municipal engineering students. The weighted‐least‐square model and Davidon–Fletcher–Powell (DFP) algorithm were used to calculate the state variable values with real‐time measurements. The software tool was composed of three modules, including network loading, state simulation, and data management. The program and the relevant graphical user interface were coded using Delphi 7.0. The performance of the software tool was proved to be effective in teaching and learning by two evaluation approaches. Moreover, the positive results also encouraged software developers and lecturers to produce or at least use computer‐aided tools for educational purposes.

Assessment of variable speed pumps in water distribution systems considering water leakage and transient operations

In this study, the potential economic and hydraulic benefits of utilizing variable speed pumps (VSPs) in water supply systems are reported. A simple water distribution network simulation is carried out by EPANET and Bentley HAMMER models to examine variable speed operation. It was found that using VSPs could control and improve performance of the water distribution systems. Where the potential energy cost savings realized by installing variable speed drives is a significant value (about 20%), in addition the leakage reduces by 21% compared to constant speed pumps. Also, this approach can improve and control undesired and damaged surge pressures and water leakage resulting from the abnormal operation conditions accompanied by the fixed speed pumping.

Optimum reliable operation of water distribution networks by minimising energy cost and chlorine dosage

In recent decades much attention has been paid to optimal operation of water distribution networks (WDNs). In this regard, the system operation costs, including energy and disinfection chemicals, as well as system reliability should be simultaneously considered in system performance optimisation, to provide the minimum required level of performance in failure condition and to manage economic limitations. In this study, multi-objective optimisation of water distribution network performance in 3 different scenarios was considered. In these scenarios the effects of time-dependent chlorine injection and pump speed, as well as different combinations of objective functions for minimising energy and disinfection costs and for maximising hydraulic reliability and quality-based reliability are incorporated. As the optimisation method, a multi-objective ant colony optimisation (ACO) algorithm was used because of its high efficiency. For better managing the hydraulic behaviour and water quality in the WDN, considering temporal variations of demand, it is suggested to use variable speed pumps (VSP) as well as to inject chlorine at a variable rate. Application of VSP and time-dependent chlorine injection results in improvements such as reduction in energy and disinfection costs, and decrease in disinfection costs in application of HDSM (head-driven simulation method). In HDSM simulation of WDN, a decrease in hydraulic reliability because of shortages in water supply can be mitigated through extra chlorine injection and increase in quality-based reliability. To deal with this challenge, it is recommended to satisfy the hydraulic reliability first and then to evaluate the quality reliability. Furthermore it is necessary to modify the hydraulic reliability relationship to incorporate different components of the WDN other than pumps. This will provide more reliable results for evaluation of the system performance.Keywords: multi-objective optimisation, aco algorithm, energy cost, disinfection costs, hydraulic reliability, quality reliability

Real-Time Simulation of Pipe Network Based on EPANET

Hydraulic simulation models of water pipe networks (WPN) are routinely used for operational investigations and network design purposes. However, their full potential is often never realized because in the majority of cases, they have been calibrated with data collected manually from the field during a single historic time period and reflects the network operational conditions that were prevalent at that time. They were then applied as part of a reactive investigation. An urban water distribution network real time simulation system based on EPANET system using OPC (object linking and Embedding for Process control) communication was built in this paper. In order to make real-time simulation of water distribution network, the real-time data was collected every 15 minutes, the real time data were received and sent into water distribution network simulation model by OPC communication of EPANET system. The real-time data included total head of reservoir, flow rate, pressure, pump operation information. The real-time simulation system can give timely warning of changes for normal network operation, providing capacity to minimize customer impact and comparing the simulation results with the real-time data collected. The real time simulation system of urban water pipe network solved the problem of data input and user interaction compare to traditional network model. It offers a way for the development of intelligent water network.

Simplification of Water Distribution Network Simulation by Topological Clustering – Investigation of its Potential Use in Copenhagen's Water Supply Monitoring and Contamination Contingency Plans

Topological clustering was investigated to simplify a complex water distribution network of Copenhagen, Denmark, into recogniz- able water movement patterns. This made it possible to assess the general transport of the water and to suggest strategic sampling locations. Through a topological analysis, the network model was divided into strongly and weakly connected clusters within selected time periods. Steady connected clusters were found by conducting a cluster analysis over all chosen selected time periods. We identified sampling locations with steady hydraulic conditions, increasing the samples’ comparability over time, and locations, where samples represent the distributed and consumed water in the Nørrebro district.

Water distribution network simulation by optimization approaches

When a fire-flow condition occurs and a nodal demand is excessive or when a pipe breaks, a water distribution system (WDS) may temporarily become deficient and unable to satisfy all nodal demands. Thus, estimation of the influences of failure conditions on the network is needed. A method for analyzing the hydraulic condition of the network in such a situation is proposed. The method, which is constructed based on the amount of supply on each consumption node, is called node flow analysis (NFA). Given the limitations of the NFA method proposed earlier for determining optimal solutions, such as inflexibility of the approach toward more complicated problems and its time-consuming process, this paper presents the honey-bee mating optimization (HBMO) algorithm for maximizing the total supply of the Two-loop and Hanoi water distribution networks (WDNs) under a failure condition. The proposed method is much faster and simpler to use than the NFA method. Consequently, obtained results confirm the higher accuracy of the proposed method to conditions of WDNs under local pipe breakage. In addition, results make one aware of the effects of each pipe breakage on consumption nodes and in the entire network under two scenarios for maximizing total supply in the network.

Modeling Local Water Storages Delivering Customer Demands in WDN Models

Water distribution network (WDN) models account for customer-demands as water withdrawals concentrated in nodes. Customer- demands can be assumed to be constant or varying with nodal head/pressure entailing demand-driven or pressure-driven simulation, respec- tively. In both cases, the direct connection of customer properties to the hydraulic system is implicitly assumed. Nonetheless, in many technical situations, the service pipe fills a local private storage (e.g., a roof tank or a basement tank) from which the water is actually delivered to customers by gravity or pumping systems. In such contexts, the service pipe fills the local tank by means of a top orifice. Consequently, what is really connected to the hydraulic system is a tank, which is subject to a filling/emptying process while supplying water to customers. Therefore, since modeling this technical situation in WDN analyses is necessary, the paper develops a formulation for nodal water withdrawals in WDN models accounting for the filling/emptying process of inline tanks between the hydraulic network and customers. The formulation is also introduced in a widely used method for steady-state WDN modeling, the global gradient algorithm, and its effectiveness to increase the hydraulic accuracy of results is discussed using a simple case study and a small network. DOI: 10.1061/(ASCE) HY.1943-7900.0000812. © 2014 American Society of Civil Engineers. Author keywords: Tank modeling; Water distribution networks; Hydraulic network modeling; Water distribution network simulation; Extended period simulation.

Generalizing WDN simulation models to variable tank levels

In water distribution network (WDN) steady-state modelling, tanks and reservoirs are modelled as nodes with known heads. As a result, the tank levels are upgraded after every steady-state simulation (snapshot) using external mass balance equations in extended period simulation (EPS). This approach can give rise to numerical instabilities, especially when tanks are in close proximity. In order to obtain a stable EPS model, an unsteady formulation of the WDN model has recently introduced. This work presents an extension of the steady-state WDN model, both for demand-driven and pressure-driven analyses, allowing the direct prediction of head variation of tank nodes with respect to an initial state. Head variations at those nodes are introduced as internal unknowns in the model, the variation of tank levels can be analyzed in the single steady-state simulation and EPS can be performed as a sequence of simulations without the need for external mass balances. The extension of mass balance at tank nodes allows the analysis of some technically relevant demand components. Furthermore, inlet and outlet head losses at tank nodes are introduced and large cross-sectional tank areas are allowed by the model and reservoirs become a special case of tanks. The solution algorithm is the generalized-global gradient algorithm (G-GGA), although the proposed WDN model generalization is universal.

Equivalent hydraulic resistance to simulate pipes subject to diffuse outflows

In water distribution network simulation models, pipes subject to diffuse outflow, either due to connections or to distributed demand or to leaks along their length, are generally converted into pipe elements only subject to lumped demand at their ending nodes. This approximation, which disregards the flow variation along the pipes, generates a loss of axial momentum, which is not correctly taken into account in the present generation of water distribution network models. In this paper a correction to the lumped demand approximation is provided and this equivalence is analyzed within the framework of the Global Gradient Algorithm. This is obtained through a correction of the pipe hydraulic resistance; this approach has proven to be more effective than the use of an asymmetrical lumped demand of the total distributed outflow at the pipe ending nodes. In order to assess the effect of the introduced correction, an application to a simple water distribution system is finally provided.