Design Of Water Distribution Systems Research Articles

Water Demand Projection in Distribution Systems Using a Novel Scenario Planning Approach

Abstract Nowadays, the world is witnessing global changes that may affect the provision of services from water utilities. The construction of demand scenarios is of the utmost importance for the planning, design and operation of water distribution systems under uncertainty conditions. The aim of this paper is to present the results of water demand projections, based on a scenario planning approach in water distribution systems for short and long terms. Results also include improved empirical relations to predict water demand variables and daily demand patterns. Temperature was incorporated in these prediction models, which significantly improved their accuracy.

Mining Solution Spaces for Decision Making in Water Distribution Systems

Data mining solutions can be applied in combination with evolutionary algorithms to extract relevant information from solution spaces analyzed during optimization processes regarding water distribution system (WDS) design. Firstly, results from data mining can be introduced into the evolutionary algorithms to guide the search of solutions. Secondly, data mining techniques can be used not only to help explore the population of potential solutions but also to exploit data regarding the behavior of the WDS under different work conditions. As a result, applications can be developed for supporting decision making regarding WDS models in both offline and online contexts.

Sequential Multi-objective Evolutionary Algorithm for a Real-world Water Distribution System Design

Abstract This paper presents a methodology based on a three-stage multi-objective optimization model for solving the problem of Battle of Background Leakage Assessment for Water Networks (BBLAWN) at WDSA2014 conference. At the first stage, the optimal design of pipeline rehabilitation, pump scheduling and tank sizing is formulated and solved on the skeletonized network by a optimizing (1) the costs of pipes, pumps and tank upgrading and (2) the cost of water losses and energy. Three optimal solutions are used for a second optimisation step on the full network (i.e. not skeletonised). The third optimisation step is then performed starting from second stage optimal solutions considering the three objectives of the original problem.

Assessment of Penalty-Free Multi-Objective Evolutionary Optimization Approach for the Design and Rehabilitation of Water Distribution Systems

This paper describes a penalty-free multi-objective evolutionary optimization approach for the phased whole-life design and rehabilitation of water distribution systems. The optimization model considers the initial construction, rehabilitation and upgrading costs. Repairs and pipe failure costs are included. The model also takes into consideration the deterioration over time of both the structural integrity and hydraulic capacity of every pipe. The fitness of each solution is determined from the trade-off between its lifetime costs and its actual hydraulic properties. The hydraulic analysis approach used, known as pressure-dependent modelling, considers explicitly the pressure dependency of the water supply consumers receive. Results for two sample networks in the literature are included that show the algorithm is stable and finds optimal and near-optimal solutions reliably and efficiently. The results also suggest that the evolutionary sampling efficiency is very high. In other words, the number of solutions evolved and analysed on average before finding a near-optimal solution is small in comparison to the total number of feasible and infeasible solutions. We found better solutions than those reported previously in the literature for the two networks considered. For the Kadu network, for example, the new best solution costs Rs125,460,980—a significant improvement. Additional statistics that are based on extensive testing are included.

An ASP approach for the valves positioning optimization in a water distribution system

Positioning of valves is a real-life issue in Water Distribution System design and, currently, it is usually addressed by hand by hydraulic engineers, or by means of genetic algorithms, that give no assurance of optimality. Since a given valves placement identifies a sectorization of the WDS in several isolable portions, the valves positioning problem can be seen as a variant of the well known graph partitioning, which is a hard combinatorial problem. [2] showed recently that Computational Logic can provide technologies and techniques that can be exploited to model and achieve the optimal partition of the water network (i.e., the optimal positioning of valves). In particular, they tackled the optimization of the valves positioning through a two player game model, giving a Constraint Logic Programming formalization to solve it effectively. The aim of this paper, instead, is to investigate the potential of Answer Set Programming in this practical application; evaluation is in terms both of language expressivity and solving efficiency. Results are discussed for different ASP models and a comparison with the CLP(FD) technique shown by [2] will be given.

Robustness-Based Design of Water Distribution Systems

AbstractRobustness is generally defined as an ability of a system to maintain its function under a defined set of disturbances. To introduce robustness to the water distribution systems (WDSs) design, chance constrained, or so-called reliability-based models have been formulated. Under variations in system parameters, such as nodal demands and pipe roughness, system reliability is generally measured as the probability that the stochastic nodal pressures will be higher than an allowable minimum pressure limit. However, chance constraints may not be the best formulation to improve system robustness because it focuses on the likelihood of failure under a specified set of conditions rather than developing a solution that consistently provides adequate service. In addition, the reliability-based design requires defining the demand condition, its probability distribution and its statistics, which are not straight forward in practice. To address these difficulties, a robustness index that limits the range of the...

Optimization of Water Distribution Systems Using Online Retrained Metamodels

AbstractThis paper proposes the use of online retrained metamodels for the optimization of water distribution system (WDS) design. In these metamodels, artificial neural networks (ANNs) are used to replace the full hydraulic and water quality simulation models and differential evolution (DE) is utilized to carry out the optimization. The ANNs in the proposed online DE-ANN model are retrained periodically during the optimization in order to improve their approximation to the appropriate portion of the search space. In addition, a local search strategy is used to further polish the final solution obtained by the online DE-ANN model. Three case studies are used to verify the effectiveness of the proposed online retrained DE-ANN model for which both hydraulic and water quality constraints are considered. In order to enable a performance comparison, a model in which a DE is combined with a full hydraulic and water quality simulation model (DE-EPANET2.0) and an offline DE-ANN model (ANNs are trained only once a...

Regulatory, Analysis, and Decision Support Challenges to Reduce Environmental Impact in the Design and Operation of Water Distribution Networks

AbstractThis paper reviews policy and research initiatives that have begun to address three major challenges to incorporate regional environmental impacts in the design and optimization of drinking water distribution systems. These challenges are to (1) develop a regulatory framework to limit the environmental impacts linked to upgrades and operation of water networks; (2) select indicators and develop models to quantify energy use, environmental impacts, and emissions for the design and operation of water distribution systems; and (3) develop decision support systems to integrate environmental sustainability objectives into the decision-making process for utilities. This paper concludes by discussing realistic steps that water utilities can take to reduce the environmental impact of their business operations.

Flexible Water Distribution System Design under Future Demand Uncertainty

In order to address the issue of water demand uncertainty due to the effect of climate change and urbanization in the design and management of water distribution systems (WDSs), a flexible methodology that combines sampling techniques (Monte Carlo—MC or Latin Hypercube—LH simulations), decision tree analysis, and genetic algorithm optimization is presented. The methodology gives flexible and optimal decisions as future water demand unfolds. The problem of optimal WDS design under uncertain future water demand is formulated here as a multiobjective optimization problem. The two objectives are as follows: (1) minimisation of total intervention cost; and (2) maximization of WDS end resilience. The decision variables are the conventional design interventions (e.g., pipe duplication and/or replacement of existing pipes with new ones, addition of tanks and pumps, etc.) and the water demand threshold values. The output from the nondominated sorting genetic algorithm (NSGA2) optimisation process is the Pareto front containing staged (developmental) design solutions represented in a decision tree form with an optimal water demand threshold value that results due to the trade-off in terms of the two objectives analyzed over the planning horizon. This methodology was applied on the New York Tunnels and the Anytown network problems. The results show that there is value achieved by building flexibility in design when compared to the deterministic approach in the long-term planning of WDSs under uncertainty.

Coupled Topology and Pipe Size Optimization of Water Distribution Systems

This paper describes a new multi-objective evolutionary optimization approach to the simultaneous layout and pipe size design of water distribution systems. Pressure-deficient and topologically infeasible solutions are fully incorporated in the genetic algorithm without recourse to constraint violation penalties or tournaments. The proposed approach is demonstrated by solving three benchmark problems taken from the literature. New optimal layouts and/or new feasible solutions that are cheaper than the best solutions in the literature were found for both branched and looped network configurations. Specifically, a new best solution was generated for each of the above-mentioned benchmark problems. In addition, the case of the looped design of a hitherto branched network in the literature was considered. Detailed results are included that show that the proposed approach achieves good solutions efficiently and consistently.

Application of linear programming for looped water supply pipe network design

It has been indicated in the literature that looped water distribution systems designed with the linear programming (LP) optimisation technique are converted into tree-like structures resulting in the disappearance of the original geometry in the final design. Looped networks are provided for system reliability, thus such a design approach will defeat the basic purpose of looped systems provision. Such a limitation has hindered the application of LP for the design of looped water supply networks. A method for the design of a looped water distribution system has been developed such that the loop configuration of the network is maintained by bringing all the pipes of the network into the optimisation problem formulation using the LP optimisation method.

Water Quality Reliability Analysis of Water Distribution Systems Based on Monte-Carlo Simulation

Water distribution systems (WDS) are important urban infrastructures which are designed for safely conveying potable water from treatment plant to users tap with adequate quantity and desired quality. The water quality reliability evaluation of WDS has positive and critical meanings for ensuring water supply security, reliability and maintaining a high level of service. In this paper, firstly the evaluation index of water quality reliability of municipal water distribution systems has been set up which is characterized by the residual chlorine availability. Then, taking into account the random nature of component failures, the variation of water demand through the 24 hours of a day and the chlorine variation of the treated water in water plant through the 24 hours of a day, the Monte Carlo-based reliability model are established based on the dynamic link library toolkit provided by EPANET 2.0 for the hydraulic and water quality calculation engine. Finally, the water quality reliability of each node and system is evaluated taking water network of some region in Tianjin Binhai High-tech Area (BHA) as example. The research results can be applied to the whole process from planning and design to operation of WDS, and the theoretical basis and decision support for optimal design and operation of WDS are provided for designers and decision-makers.

Multiobjective Optimization for Least Cost Design and Resiliency of Water Distribution Systems

AbstractThe multiobjective optimization model described in this study is aimed at exploring the tradeoff between cost and resiliency for water distribution systems optimal design. Many have dealt previously with minimizing cost where reliability was quantified as a constraint. Fewer considered both cost and reliability as objectives. This work suggests a methodology for least cost versus reliability (quantified as resiliency) optimal design, introducing the following contributions: (1) a genetic algorithm multiobjective formulation integrating a previous theoretical result of a possible maximum of two adjacent discrete pipe diameters for a single pipe; (2) comparable results to previous best least-cost design solutions for the two-looped and Hanoi networks; (3) a real life-sized example application analysis for pipes reinforcement; and (4) an interpretation of resiliency through its comparison to two explicit reliability measures involving demands increase and pipes failure, reconfirming that resiliency i...

Hybrid metaheuristics for multi-objective design of water distribution systems

Multi-objective design of Water Distribution Systems (WDSs) has received considerable attention in the past. Multi-objective evolutionary algorithms (MOEAs) are popular in tackling this problem due to their ability to approach the true Pareto-optimal front (PF) in a single run. Recently, several hybrid metaheuristics based on MOEAs have been proposed and validated on test problems. Among these algorithms, AMALGAM and MOHO are two noteworthy representatives which mix their constituent algorithms in contrasting fashion. In this paper, they are employed to solve a wide range of benchmark design problems against another state-of-the-art algorithm, namely NSGA-II. The design task is formulated as a bi-objective optimisation problem taking cost and network resilience into account. The performance of three algorithms is assessed via normalised hypervolume indicator. The results demonstrate that AMALGAM is superior to MOHO and NSGA-II in terms of convergence and diversity on the networks of small-to-medium size; however, for larger networks, the performance of hybrid algorithms deteriorates as they lose their adaptive capabilities. Future improvement and/or redesign on hybrid algorithms should not only adopt the strategies of adaptive portfolios of sub-algorithms and global information sharing, but also prevent the deterioration mainly caused by imbalance of constituent algorithms.

Comparison of the robustness-based optimal designs of water distribution systems in three different formulations

Robustness is generally defined as a system's ability to stay within satisfactory bounds against variations in system factors. Recently, robustness has been indicated to be a useful objective function for the optimal design of water distribution systems (WDSs). While various formulations are possible to represent WDS robustness, few efforts have been made to compare the performances of these formulations. This study examined three potential formulations for quantifying system robustness to provide guidelines on the usage of a robustness index. Giustolisi et al.'s robustness index (see Giustolisi et al. (2009) ‘Deterministic versus stochastic design of water distribution networks’, J. Water Resour. Plann. Manage.135 (2), 117–127) was adopted to calculate nodal robustness, while the system robustness was defined using three different formulations: (1) minimum among nodal robustness values; (2) total sum of nodal robustness; and (3) sum of nodal robustness at multiple critical nodes. The three proposed formulations were compared through application to identify the most appropriate one for enhancing system robustness in general; three representative benchmark networks were optimally designed to minimize the economic cost while maximizing the system robustness.

Battle of the Water Networks II

The Battle of the Water Networks II (BWN-II) is the latest of a series of competitions related to the design and operation of water distribution systems (WDSs) undertaken within the Water Distribution Systems Analysis (WDSA) Symposium series. The BWN-II problem specification involved a broadly defined design and operation problem for an existing network that has to be upgraded for increased future demands, and the addition of a new development area. The design decisions involved addition of new and parallel pipes, storage, operational controls for pumps and valves, and sizing of backup power supply. Design criteria involved hydraulic, water quality, reliability, and environmental performance measures. Fourteen teams participated in the Battle and presented their results at the 14th Water Distribution Systems Analysis conference in Adelaide, Australia, September 2012. This paper summarizes the approaches used by the participants and the results they obtained. Given the complexity of the BWN-II problem and the innovative methods required to deal with the multiobjective, high dimensional and computationally demanding nature of the problem, this paper represents a snap-shot of state of the art methods for the design and operation of water distribution systems. A general finding of this paper is that there is benefit in using a combination of heuristic engineering experience and sophisticated optimization algorithms when tackling complex real-world water distribution system design problems.

Impacts of supply duration on the design and performance of intermittent water distribution systems in the West Bank

This paper analyzes the intermittent water distribution system in the West Bank, Palestine. It quantifies the impacts of reduced supply duration on the hydraulics and costs of water distribution. It shows that designing systems based on intermittent supply criteria implies increasing the diameters of pipes significantly, which is expensive and infeasible. The paper recommends that studying the local conditions should precede the design of new systems to avoid reduced supply duration and related negative impacts. In addition, improving governance, revising tariffs, reducing leakage, saving water, involving the private sector, and improving water diplomacy should be considered in any water policy reform.

Coupled Binary Linear Programming–Differential Evolution Algorithm Approach for Water Distribution System Optimization

AbstractA coupled binary linear programming–differential evolution (BLP-DE) approach is proposed in this paper to optimize the design of water distribution systems (WDS). Three stages are involved in the proposed BLP-DE optimization method. In the first stage, the WDS that is being optimized is decomposed into trees and the core using a graph algorithm. Binary linear programming is then used to optimize the design of the trees during the second stage. In the third stage, a differential evolution (DE) algorithm is utilized to deal with the core design while incorporating the optimal solutions for the trees obtained in the second stage, thereby yielding near-optimal solutions for the original whole WDS. The proposed method takes advantage of both the BLP and DE algorithms: BLP is capable of providing a global optimal solution for the trees (no loops involved) with great efficiency, and a DE is able to efficiently generate good quality solutions for the core (loops involved) with a reduced search space compa...

Reducing life-cycle carbon footprint in the (re)design of water distribution systems using water demand management interventions

Water distribution systems (WDSs) construction, operation and disposal processes contribute to undesirable greenhouse gas (GHG) emissions. GHG concentration in the atmosphere is strongly associated with global warming and climate change. In order to meet the consequent challenge of limiting GHG emissions, the problem of WDS (re)design is formulated here as a multi-objective optimisation problem. The three objectives are as follows: (1) minimisation of total (re)design cost, (2) maximisation of the WDS resilience and, (3) minimisation of GHGs emissions. In addition to the frequently considered conventional (re)design intervention options (new pipes, pipe duplication or replacement, addition of pumps, tanks, etc.), various water demand management interventions (e.g. water efficient appliances and domestic Rainwater Harvesting Systems) are considered here too. A number of different rainwater tank sizes and water saving appliances provided to different parts of the households have been evaluated. This methodology was applied on the New York Tunnels and the Anytown network problems. The output from the Non-dominated Sorting Genetic Algorithm (NSGA2) optimisation process is a Pareto front containing optimal solutions traded-off in terms of the three objectives analysed. The results obtained demonstrate that using demand management technologies in the (re)design of WDSs can lead to a similar cost, resilience and GHG emissions but with cost savings. In a pumped WDS where cost savings and GHG emission reduction are relatively significant, demand management technologies led to more cost effective, resilient and climate change mitigating solutions as compared to the conventional (re)design.

Research Database of Water Distribution System Models

AbstractSince the 1960s, researchers have continued to develop new methodologies and algorithms in support of the planning, design, and management of water distribution systems. While initial research focused on modeling the hydraulics of such systems, the 1980s gave rise to additional research focus on water quality issues. More recent research has expanded into issues of system reliability and resilience, energy management, and sensor and chlorine booster station placement. In most cases, researchers have relied on either hypothetical water distribution systems or a handful of actual systems for use as benchmark test systems. Some of the more widely used actual systems include the New York tunnel system and the Hanoi water distribution system. This paper describes the development of a database of several water distribution systems synthesized from a statewide database of systems originally developed by the Kentucky Infrastructure Authority. The developed models include both small and medium networks, as...