Large-scale Water Distribution Systems Research Articles

Reducing Water Conveyance Footprint through an Advanced Optimization Framework

This study investigates the optimal and safe operation of pumping stations in water distribution systems (WDSs) with the aim of reducing the environmental footprint of water conveyance processes. We introduced the nonlinear chaotic honey badger algorithm (NCHBA), a novel and robust optimization method. The proposed method utilizes chaotic maps to enhance exploration and convergence speed, incorporating a nonlinear control parameter to effectively balance local and global search dynamics. Single-objective optimization results on a WDS show that NCHBA outperforms other algorithms in solution accuracy and convergence speed. The application of the proposed approach on a water network with two variable-speed pumps demonstrated a significant 27% reduction in energy consumption. Expanding our focus to the multi-objective optimization of pump scheduling programs in large-scale water distribution systems (WDSs), we employ the non-dominated sorting nonlinear chaotic honey badger algorithm (MONCHBA). The findings reveal that the use of variable-speed pumps not only enhances energy efficiency but also bolsters WDS reliability compared to the use of single-speed pumps. The results showcase the potential and robustness of the proposed multi-objective NCHBA in achieving an optimal Pareto front that effectively balances energy consumption, pressure levels, and water quality risk, facilitating carbon footprint reduction and sustainable management of WDSs.

Insights for booster chlorination strategy based on DBPs control in a large-scale water supply system

Based on a one-year field investigation of disinfection by-products (DBPs) in large scale water distribution system (LSWDS), the various characteristics of DBPs together with their correlation with booster chlorination were elaborated through ArcGIS model. Furthermore, the effects of booster chlorination on DBP formation were investigated through simulated experiments. Residual chlorine showed a strong relationship with occurrence of different DBPs in LSWDS, and the yield of DBPs increased significantly after booster chlorination. The simulated chlorination experiments showed that diminution of the ratio of primary to secondary (booster) chlorination dosage, and delaying the secondary chlorine addition reduced the generation of DBPs during water conveyance. The yield concentrations of THMs and HAAs obviously increased after booster chlorination. The correlation between HAAs and chlorine dosage is weaker in the field research than in the simulation experiment while THMs had a positive correlation with the chlorine addition in both field research and simulation experiment.

An Efficient Approach for Nodal Water Demand Estimation in Large-scale Water Distribution Systems

Real-time modeling of a water distribution system (WDS) is a critical step for the control and operation of such systems. The nodal water demand, as the most important time-varying parameter, must be estimated in real time. The computational burden of nodal water demand estimation is intensive, leading to inefficiency in the modeling of large-scale networks. The Jacobian matrix computation and Hessian matrix inversion are the main processes that dominate the computation time. To address this problem, an approach for shortening the computation time for real-time demand estimation in large-scale network is proposed. This approach allows the Jacobian matrix to be efficiently computed based on solving a system of linear equations, and a Hessian matrix inversion method based on matrix partitioning and the iterative Woodbury-Matrix-Identity Formula is proposed. The developed approach is applied to a large-scale network, in which the number of nodal water demands is 12523, and the number of measurements ranges from 10 to 2000. The results show that the time consumptions for the Jacobian computation and Hessian matrix inversion are within 465.3 ms and 1219.0 ms, respectively. The time consumption is significantly shortened compared with the existing approach, especially for nodal water demand estimation in large-scale WDSs.

Bayesian Localization of Water Distribution System Contamination Intrusion Events Using Inline Mobile Sensor Data

AbstractThe intrusion of a foreign substance into the water distribution system represents a serious threat to public health. Large-scale water distribution systems serve thousands of consumers who...

GPU Acceleration of Hydraulic Transient Simulations of Large-Scale Water Supply Systems

Simulating hydraulic transients in ultra-long water (oil, gas) transmission or large-scale distribution systems are time-consuming, and exploring ways to improve the simulation efficiency is an essential research direction. The parallel implementation of the method of characteristics (MOC) on graphics processing unit (GPU) chips is a promising approach for accelerating the simulations, because GPU has a great parallelization ability for massive but simple computations, and the explicit and local features of MOC meet the features of GPU quite well. In this paper, we propose and verify a GPU implementation of MOC on a single chip for more efficient simulations of hydraulic transients. Details of GPU-MOC parallel strategies are introduced, and the accuracy and efficiency of the proposed method are verified by simulating the benchmark single pipe water hammer problem. The transient processes of a large scale water distribution system and a long-distance water transmission system are simulated to investigate the computing capability of the proposed method. The results show that GPU-MOC method can achieve significant performance gains, and the speedup ratios are up to hundreds compared to the traditional method. This preliminary work demonstrates that GPU-MOC parallel computing has great prospects in practical applications with large computing load.

A Stochastic Framework for Reliability and Sensitivity Analysis of Large Scale Water Distribution Networks

The hydraulic reliability and sensitivity analysis of large scale water distribution systems in presence of uncertainty is considered in this work. The assessment of the network reliability and sensitivity is performed by an efficient Markov chain Monte Carlo method, namely Subset simulation. Prescribed nodal heads of storage tanks, nodal demands and pipe roughness coefficients are modeled as uncertain parameters and described in a probabilistic manner. Failure is assumed to occur when the minimum nodal head in the network is lower than a minimum allowable value. The efficiency of the proposed method is demonstrated with the analysis of a real water distribution network consisting of a large number of nodes and pipes (of the order of thousands). The corresponding reliability problem represents a high dimensional problem. The approach gives an important insight into the performance, reliability and sensitivity of a class of complex utility networks.

A Spark-based genetic algorithm for sensor placement in large scale drinking water distribution systems

Water pollution incidents have occurred frequently in recent years, causing severe damages, economic loss and long-lasting society impact. A viable solution is to install water quality monitoring sensors in water supply networks (WSNs) for real-time pollution detection, thereby mitigating the risk of catastrophic contamination incidents. Given the significant cost of placing sensors at all locations in a network, a critical issue is where to deploy sensors within WSNs, while achieving rapid detection of contaminant events. Existing studies have mainly focused on sensor placement in water distribution systems (WDSs). However, the problem is still not adequately addressed, especially for large scale WSNs. In this paper, we investigate the sensor placement problem in large scale WDSs with the objective of minimizing the impact of contamination events. Specifically, we propose a two-phase Spark-based genetic algorithm (SGA). Experimental results show that SGA outperforms other traditional algorithms in both accuracy and efficiency, which validates the feasibility and effectiveness of our proposed approach.

A Graph-Theoretic Framework for Assessing the Resilience of Sectorised Water Distribution Networks

Water utilities face a challenge in maintaining a good quality of service under a wide range of operational management and failure conditions. Tools for assessing the resilience of water distribution networks are therefore essential for both operational and maintenance optimization. In this paper, a novel graph-theoretic approach for the assessment of resilience for large scale water distribution networks is presented. This is of great importance for the management of large scale water distribution systems, most models containing up to hundreds of thousands of pipes and nodes. The proposed framework is mainly based on quantifying the redundancy and capacity of all possible routes from demand nodes to their supply sources. This approach works well with large network sizes since it does not rely on precise hydraulic simulations, which require complex calibration processes and computation, while remaining meaningful from a physical and a topological point of view. The proposal is also tailored for the analysis of sectorised networks through a novel multiscale method for analysing connectivity, which is successfully tested in operational utility network models made of more than 100,000 nodes and 110,000 pipes.

Flexible Reconfiguration of Existing Urban Water Infrastructure Systems.

This paper presents a practical methodology for the flexible reconfiguration of existing water distribution infrastructure, which is adaptive to the water utility constraints and facilitates in operational management for pressure and water loss control. The network topology is reconfigured into a star-like topology, where the center node is a connected subset of transmission mains, that provides connection to water sources, and the nodes are the subsystems that are connected to the sources through the center node. In the proposed approach, the system is first decomposed into the main and subsystems based on graph theory methods and then the network reconfiguration problem is approximated as a single-objective linear programming problem, which is efficiently solved using a standard solver. The performance and resiliency of the original and reconfigured systems are evaluated through direct and surrogate measures. The methodology is demonstrated using two large-scale water distribution systems, showing the flexibility of the proposed approach. The results highlight the benefits and disadvantages of network decentralization.

Automated sub-zoning of water distribution systems

Water distribution systems (WDS) are complex pipe networks with looped and branching topologies that often comprise thousands to tens of thousands of links and nodes. This work presents a generic framework for improved analysis and management of WDS by partitioning the system into smaller (almost) independent sub-systems with balanced loads and minimal number of interconnections. This paper compares the performance of three classes of unsupervised learning algorithms from graph theory for practical sub-zoning of WDS: (1) Global clustering – a bottom-up algorithm for clustering n objects with respect to a similarity function, (2) Community structure – a bottom-up algorithm based on the property of network modularity, which is a measure of the quality of network partition to clusters versus randomly generated graph with respect to the same nodal degree, and (3) Graph partitioning – a flat partitioning algorithm for dividing a network with n nodes into k clusters, such that the total weight of edges crossing between clusters is minimized and the loads of all the clusters are balanced. The algorithms are adapted to WDS to provide a practical decision support tool for water utilities. Visual qualitative and quantitative measures are proposed to evaluate models' performance. The three methods are applied for two large-scale water distribution systems serving heavily populated areas in Singapore.

Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems

Abstract. This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN), taking into account pressure aspects such as minimum service pressure and pressure-dependent leakage. An optimisation model is automatically generated in the GAMS language from a hydraulic model in the EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP). The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in the EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for a variety of requirements.

Research on Optimal Operation Method of Large Scale Urban Water Distribution System

In consideration of using fewer decision variables in building least cost pumping operation optimal, the two-phase optimal method is used as the frame. By abstracting pump stations into high level reservoirs, the water distribution system hydraulic model can be modified into a modality, which can be used in first optimal phase of two-phase optimal method. And by building on feasible pump combination database, a new optimal method in the second optimal phase will be proposed. And the proposed new method in the second optimal phase will be embedded into the first optimal phase, so that the problem of results discordant in different phases of two-phase optimal method will be solved. By introducing new concept and improving present optimal method, a more practical optimal operation method of water distribution system (WDS) will be established. By applying to a large scale water distribution system, the practicability of proposed method has been evaluated.

Planning and Operation of Large-Scale Water Distribution Systems with Preemptive Priorities

This paper describes the development of an optimization model for the management and operation of a large-scale, multireservoir water supply distribution system with preemptive priorities. The model considers multiobjectives and hedging rules. During periods of drought, when water supply is insufficient to meet the planned demand, appropriate rationing factors are applied to reduce water supply. In this paper, a water distribution system is formulated as a network and solved by the GAMS modeling system for mathematical programming and optimization. A user-friendly interface is developed to facilitate the manipulation of data and to generate graphs and tables for decision makers. The optimization model and its interface form a decision support system (DSS), which can be used to configure a water distribution system to facilitate capacity expansion and reliability studies. Several examples are presented to demonstrate the utility and versatility of the developed DSS under different supply and demand scenarios, including applications to one of the largest water supply systems in the world, the São Paulo Metropolitan Area Water Supply Distribution System in Brazil.

Planned Operation of Large-Scale Water-Distribution System

A water-supply-distribution-system planning model has been developed using a directed graph algorithm as its pre- and postprocessors and a linear programming (LP) procedure as an “intelligent” system operator at its core. The directed graph, as a preprocessor, is used to produce a mathematical representation of the distribution system in question, to check the consistency and correctness of the network topology before an input file is created for the LP procedure. In the postprocessing mode, the directed graph generates files for graphical displays of model results and performs graph analyses such as depth- and breadth-first traversals, cut-set and connectivity for evaluating water-quality blending, tracking of source-to-demand contributions, system reliability, and lifeline objectives. Unlike the conventional formulation of a resource-allocation problem, the demand requirements, storage capacities, and other system constraints are removed from the constraint set and translated into a composite objective function. This methodology was successfully applied to the Metropolitan Water District of Southern California's (MWD's) distribution system. The results indicate that the combination of using an LP procedure and graph algorithm is a very versatile tool for solving large-scale water-distribution problems. This paper documents the concept used in developing the system-planning model and the results of its application to a simplified example as well as application to four case studies involving the entire MWD's distribution system.

Analysis of large scale water distribution systems

A variety of methodologies is currently available for computing flows in water distribution systems. One of these methods is the Newton-Raphson method which regenerates and factorizes Jacobian matrix at each iteration. In this method a great deal of computational effort is consumed in the determination and factorization of the Jacobian matrix.One alternative approach is to use the initial Jacobian matrix throughout, thus avoiding the expense of reforming and triangularizing the Jacobian matrix. However, in this approach the quadratic convergence characteristic of the Standard Newton-Raphson Method is no longer maintained. As a compromise between these two approaches, a class of methods known as Quasi-Newton Methods can be utillized. This paper presents a computer model which incorporates the use of Quasi-Newton Methods in the solution of large scale water distribution systems. Three water distribution systems of varying sizes were analyzed using this method. The computer results obtained using the Quasi-N...

Real-time Simulation of Water Distribution System

In this paper real-time simulation of water distribution system is presented. Purpose of the system is to help understanding water distribution system performances, to prepare plans for normal and emergency conditions and dispatcher training. Special attention is paid to software design which allows real-time model behavior, multi-user interaction, ad hoc processing of input commands, and various CRT displays. Software architecture is parallel: the system is divided into three independent processes (input, output, calculation). Processes execute concurrently and special primitives are defined for their communication and synchronization. Man-machine interface is designed to meet requirement of user-friendly interaction. The system provides two regimes of work and several speeds of simulation. It records simulation history, allows repetition of a previous simulation starting from the arbitrarily chosen time point, and provides efficient tools for monitoring and analyzing behavior of the large scale water distribution system.

Optimal Development of Multipurpose Hydro Projects

The Environmental Protection Act has created many complications for any hydroelectric power project. For mixed agency (public and private) developments, there are broad effects resulting from recent court decisions under the Sherman Anti-Trust Act. The economic impact of fuel shortages and costs result in a necessity for reevaluation of existing hydroelectric projects. The writer's term Energy recovery projects refers to the conversion of hydraulic head breaking plants to power plants. On large-scale water distribution systems such a development can save the equivalent of many hundreds of barrels of oil per day. The basic problems unique to this type of development are examined. This paper examines the effects of these changes on proposed hydroelectric power redevelopments, and energy recovery projects. A practical example of optimal development of a power drop currently being considered for base load utilization is analyzed.