Design Of Water Distribution Networks Research Articles

Investigation of sustainable and resilient design alternatives for water distribution networks

Nowadays there is a pronounced interest in the need for sustainable and resilient infrastructure systems to address the challenges of future infrastructure development. This paper presents a three-objective optimization model for the investigation of various sustainable and resilient design alternatives for water distribution networks. Although optimal design of water distribution networks is a thoroughly studied area, most researchers focused on efficient algorithms to solve the complex design problem. Cost has predominantly been the objective in previous studies with few models also considering resilience or environmental impacts (CO2 emissions). This research combined all these parameters in a multi-objective model to obtain various sustainable and resilient design alternatives. The model is demonstrated on a three-loop benchmark network that was previously studied. The tradeoff between the objectives is further analyzed to identify the most beneficial solution from the pareto-optimal set of solutions. The dollar worth of enhancing resilience of the benchmark network by a unit is estimated to be in the range of $1.23 to $3.93 million, which translates to about 22% to 69% of the least possible life cycle cost. The results of this research reveal that resilience can be increased by paying a justifiable cost that will also compensate for CO2 emissions.

Reliability based optimal design of a municipal water supply pipe network

This paper intends to provide a detailed methodology on the development of the optimization model including reliability for design of water distribution networks using genetic algorithms (GA) and EPANET in the MATLAB environment. The coding developed is easy to use and also flexible. A new parameter is proposed to determine the overall network reliability using network nodal demands and their corresponding satisfaction indices and is incorporated in the optimization model. The proposed methodology is tested on a standard Hanoi network. After several runs and out of many optimal solutions obtained, the solution with a total cost of 7.78 million associated with a reliability of 0.7323 is considered as the best and the corresponding results are presented and compared with previous research.

Comparison of various phased approaches for the constrained minimum-cost design of water distribution networks

In most cases, water system design is based on a demand forecast at the end of some planning horizon based on the final configuration of the system at that time. This design approach (aimed at designing all the network at a time) is incompliant with its actual development, which instead takes place in phases. As a consequence, in order to follow the network demand and layout growth in time, practitioners prefer to sub-divide the whole construction life into various time phases thus including the different phases of construction in the network design.This work is aimed at analyzing and comparing three different phased approaches for constrained minimum-cost design of water distribution networks: the single-phase design with demand feedback, the multi-phase design without demand feedback and the multi-phase design with demand feedback. The difference between the single-phase design and the multi-phase design lies in the fact that whereas the former entails optimizing a single construction phase at a time, i.e. the current construction phase, the latter is based on the phasing of construction and then is aimed at optimizing the current construction phase and all the subsequent phases, included inside a certain temporal horizon, simultaneously. The demand feedback is here used as a pragmatic tool for updating the forecast at some specific time instant of the future demand growth: such an update is performed by setting the future demand growth equal to that really observed in the previous time phase. Alternatively, the predicted demand growth rate at the generic time instant can be kept equal to the value assumed at the time instant when the generic node appears, without taking account of the demand variation really observed in time in the node (absence of demand feedback).Applications to a real case study show that the multi-phase design with the demand feedback is the most reliable because it makes it possible to reduce the overall construction costs while attenuating the occurrence of pressure deficits in the various construction phases of the network. Optimal design for a single phase will virtually guarantee a sub-optimal solution over the long run.

A Multicriteria Approach for a Phased Design of Water Distribution Networks

Water distribution networks are key infrastructurethat provide essential water supply to communities. Planning water distribution networks involves many actors, including water companies, governments, environmentalists, consumers and financing institutions, and they tend to have conflicting perspectives. This work proposes a multi-criteria decision analysis (MCDA) as a useful tool for providing decision support in such circumstances. A phased planning horizon scheme is proposed that identifies the design for the first time interval while considering possible future conditions that the network might have to cope with. The results identify the bestranked phased design solutions.

WDNetXL: Hydraulic and Topology Analysis Integration and Features

The WDNetXL is an integrated system for water distribution network (WDN) analysis, planning and management distributed as MS-Excel® add-ins. It integrates advanced and robust WDN hydraulic simulation with topological analysis and optimization strategies to support technicians for complex WDN analysis, design and management problems. The paper presents in details the feature of functions devoted to network hydraulic and topology analysis and discusses the technical effectiveness also with respect to planning and management tasks of hydraulic systems.

The role of balancing tanks in optimal design of water distribution networks

Optimisation and reliability assessment of water distribution networks are complicated processes. Most of the research focuses only on the pipes without considering other network components, such as tanks. Despite the benefits that the tanks may bring, they are usually omitted in the optimisation process or in reliability considerations. Various indices from the literature that describe network reliability are calculated exclusively based on pipe failure analyses for single demand scenario, without taking into consideration the volume of possibly existing balancing tanks. The research discussed in this paper aims to incorporate the demand balancing tanks to the optimisation process and also find out their influence on the total cost and reliability of the network. A tool called NORAT (Networks Optimisation and Reliability Assessment Tool) has been used, which determines the required balancing volume, optimises pipe diameters and tank elevations and finally calculates the total cost of supply. NORAT further assesses the hydraulic reliability of the network. The tool has been tested on a synthetic network by applying different combinations of topography, supply schemes and locations of water sources and tanks. The results prove the ability of NORAT to employ balancing tanks, both in optimisation and reliability assessment processes.

A Tsallis entropy-based redundancy measure for water distribution networks

A measure of redundancy inherent in the layouts of water distribution networks is developed using the Tsallis entropy. Both the local redundancy at a node and the global redundancy due to the redundancies at adjacent nodes are derived. The redundancy measure is applied to layouts reported in the literature and is compared with the Shannon entropy-based measure. Using the values reported in the literature, it is shown that there is almost a one-to-one relation between the Shannon entropy and the Tsallis entropy-based redundancy and reliability and this relation allows to specify the reliability of a network whose redundancy is known. Hence, the redundancy measure can also be employed in the water distribution network design.

A critical review of sensor location methods for contamination detection in water distribution networks

Water distribution networks (WDNs) are vulnerable to various types of contamination events that may have impacts on human health and the environment. Therefore, there is a growing need to design an effective monitoring system. Due to the cost of both placing and maintaining the sensors, their numbers must be limited. This constraint makes the sensor deployment locations crucial in water monitoring systems. Several methodologies have been suggested in the past two decades by different researchers for placement of sensors in WDNs. These methodologies differ in many ways depending on the number of objectives, solution methodology, concentration level of contaminant considered, type of simulation, and so on. In this paper, various methodologies have been broadly classified based on the number of performance objectives as single and multi-objective sensor location problems. Some of the features of these methodologies are also mentioned to help understand the advantages of a particular method over other methods. A critical review of literature is presented. Some of the issues on which a consensus is being developed amongst researchers are discussed and recommendations are made with a view to suggest future research needs for sensor network design of large WDNs.

Adaptive Mutated Momentum Shuffled Frog Leaping Algorithm for Design of Water Distribution Networks

With the introduction of intelligent heuristic optimization strategies, there has been an increasing interest in the use of these methods for solving the design problem of water distribution networks (WDN). This paper proposes the use of a new version of heuristic shuffled frog leaping (SFL) algorithm for solving the problem of WDN design. First, in order to speed up the original SFL algorithm, an adaptive parameter is introduced. Then, momentum parts are added to the SFL to increase the ability of the algorithm in escaping from local optimums. Finally, a mutation operator is proposed to increase the diversification property of the algorithm. The new version of the SFL algorithm is called adaptive mutated momentum shuffled frog leaping (AMMSFL). The proposed AMMSFL is then applied to solve WDN design problems. An illustrative and comparative illustrative example is presented to show the efficiency and superiority of the introduced AMMSFL compared to the other well-known heuristic algorithms.

Multi-objective optimization of water distribution systems based on a real options approach

This paper describes a multi-objective optimization model including Real Options concepts for the design and operation of water distribution networks. This approach is explained through a case study with some possible expansion areas defined to fit different future scenarios. A multi-objective decision model with conflicting objectives is detailed. Also, environmental impacts are considered that take into account not only the life cycle carbon emissions of the different materials used during the construction of the networks but also the emissions related to energy consumption during operation. These impacts are translated by giving a cost to each tonne of carbon dioxide emitted. This work presents a new multi-objective simulated annealing algorithm linked to a hydraulic simulator to verify the hydraulic constraints, and the results are represented as points on the Pareto front. The results show that the approach can deal explicitly with conflicting objectives, with environmental impacts and with future uncertainty.

Improving the efficiency of multi-objective evolutionary algorithms through decomposition: An application to water distribution network design

Evolutionary algorithms (EAs) have been widely used in handling various water resource optimization problems in recent years. However, it is still challenging for EAs to identify near-optimal solutions for realistic problems within the available computational budgets. This paper introduces a novel multi-objective optimization method to improve the efficiency of a typically difficult water resource problem: water distribution network (WDN) design. In the proposed approach, a WDN is decomposed into different sub-networks using decomposition techniques. EAs optimize these sub-networks individually, generating Pareto fronts for each sub-network with great efficiency. A propagation method is proposed to evolve Pareto fronts of the sub-networks towards the Pareto front for the full network while eliminating the need to hydraulically simulate the intact network itself. Results from two complex realistic WDNs show that the proposed approach is able to find better fronts than conventional full-search algorithms (optimize the entire network without decomposition) with dramatically improved efficiency.

Spatial Approach for Preliminary Design of Real Water Distribution Network

Spatial Approach for Preliminary Design of Real Water Distribution Network

Optimal Design of Water Distribution Networks Considering Fuzzy Randomness of Demands Using Cross Entropy Optimization

This paper presents cross entropy (CE) optimization for optimal design of water distribution networks (WDN) under demand uncertainty. In design of WDNs, it is desired to achieve a minimum cost WDN that provides higher reliability in meeting the demands. To achieve these goals, an optimization model is formulated for design of WDNs with an objective of minimizing the total cost of WDN subject to meeting the nodal demands at a specified system reliability, mass conservation and other physical constraints. The uncertainty in future water demands is modeled using the theory of fuzzy random variable (FRV). The water demand at each node is assumed to be following a normal distribution with a fuzzy mean, and 10 % (or 20 %) of the fuzzy mean as its standard deviation. The water demand is represented as a triangular fuzzy number with the random demand as its kernel, and the interval of ±5 % (or ±10 %) variation of the random demand as its support for two scenarios. The fuzzy random system reliability (R) of WDNs is defined on the basis of necessity measure to assess system performance under fuzzy random demands and crisp head requirements. The latin hypercube sampling method is adopted for sampling of uncertain demands. The methodology is applied to two WDNs, and optimization models are solved through cross entropy optimization for different levels of reliability, and generated tradeoffs between the cost and R. On comparing the solutions obtained with the proposed methodology with earlier reported solutions, it is noted that the proposed method is very effective in producing robust optimal solutions. On analyzing the tradeoffs between reliability and costs, the results show that negligence of uncertainty can lead to under design of the WDNs, and the cost increases steeply at higher levels of reliability. The results of the two case studies demonstrate that the presented CE based methodology is effective for fuzzy-probabilistic design of WDNs.

Using Real Options in the Optimal Design of Water Distribution Networks

AbstractWater supply systems have to satisfy water needs in terms of quantity and quality. The constant changes in urban areas require the regular adaptation of the water supply infrastructure to meet new circumstances. However, decisions to design and operate water networks have to be taken under uncertainty. Flexibility is thus the key to more robust and confident decisions. An approach called real options (ROs) can be used in these situations. This approach makes it possible to use adaptive strategies in the decision process. Some decisions can be delayed pending future conditions. Water distribution systems are very costly and complex infrastructures. Once built, their operating structure cannot be changed significantly. This work presents an innovative ROs approach to define an objective function to cope with some future scenarios in a specific case study. The objective of our proposed model is to find a minimum cost solution for the first period of a planning horizon, while considering various possi...

Soccer league competition algorithm: A novel meta-heuristic algorithm for optimal design of water distribution networks

Water distribution networks are one of the most important elements in the urban infrastructure system and require huge investment for construction. Optimal design of water systems is classified as a large combinatorial discrete non-linear optimization problem. The main concern associated with optimization of water distribution networks is related to the nonlinearity of discharge-head loss equation, availability of the discrete nature of pipe sizes, and constraints, such as conservation of mass and energy equations. This paper introduces an efficient technique, entitled Soccer League Competition (SLC) algorithm, which yields optimal solutions for design of water distribution networks. Fundamental theories of the method are inspired from soccer leagues and based on the competitions among teams and players. Like other meta-heuristic methods, the proposed technique starts with an initial population. Population individuals (players) are in two types: fixed players and substitutes that all together form some teams. The competition among teams to take the possession of the top ranked positions in the league table and the internal competitions between players in each team for personal improvements are used for simulation purpose and convergence of the population individuals to the global optimum. Results of applying the proposed algorithm in three benchmark pipe networks show that SLC converges to the global optimum more reliably and rapidly in comparison with other meta-heuristic methods.

Design of water distribution networks using accelerated momentum particle swarm optimisation technique

Optimisation of looped water distribution networks (WDNs) has been recognised as an NP-hard combinatorial problem which cannot be easily solved using traditional mathematical optimisation techniques. This article proposes the use of a new version of heuristic particle swarm optimisation (PSO) for solving this problem. In order to increase the convergence speed of the original PSO algorithm, some accelerated parameters are introduced to the velocity update equation. Furthermore, momentum parts are added to the PSO position updating formula to get away from trapping in local optimums. The new version of the PSO algorithm is called accelerated momentum particle swarm optimisation (AMPSO). The proposed AMPSO is then applied to solve WDN design problems. Some illustrative and comparative illustrative examples are presented to show the efficiency of the introduced AMPSO compared with some other heuristic algorithms.

Shortest path criterion for sampling design of water distribution networks

Sampling design is often required for an appropriate assessment of monitoring points in water distribution networks to increase the effectiveness of measured data in calibrating the hydraulic model. Although many methods are available in the literature, they may be inadequate for reliable network calibration. This paper proposes a new method for the optimal collocation of monitoring points using a shortest path based approach. The monitoring points are identified by minimizing the sum of node distances from the closest sensor-node. Node distances were taken to be a weighted sum of the dimensionless arc length and the absolute head loss along arc. To ensure robustness with respect to the presence of outliers among pipe lengths and/or pressure drops, adequate reference measures were chosen for normalization. The optimization problem was solved using Mixed Integer Programming and a variant of the K-Means algorithm. Alternative formulations considering different path blending and distance norms were also analyzed. Numerical experiments carried out on both theoretical and real water distribution networks showed the reliability of the proposed approach and a greater effectiveness compared to similar methods available in the literature.

Comparison of Flow-distribution Models for Design of Water Distribution Networks with Redundancy

Abstract Five flow-distribution models are compared for optimal design of looped water distribution networks (WDNs) with redundancy. A two-stage iterative methodology, in which a WDN designed using LP in the first stage for the selected flow-distribution corresponding to all-pipes working condition, is checked in the second stage for its performance under failure conditions. The LP problem of first stage is modified to additionally include the flow-distribution for the most critical pipe-failure condition. The methodology is continued until network becomes satisfactory under multiple single pipe failures. It is observed that the Chiong's flow-distribution model provided minimum cost design with redundancy for illustrative network .

GA-NR for optimal design of water distribution networks

Optimal design of water distribution networks is the most important and challenging issue in the 21st century. Evolutionary algorithms are evolved as efficient approach to optimise such problems. In this paper, a real coded genetic algorithm, MILXPM, is hybridised with Newton-Raphson method for the optimal design of water distribution networks. Proposed MILXPM-NR is tested on three different test problems. Results show that it is an efficient and reliable algorithm for optimal design of water distribution networks.

Decision Support for Optimal Design of Water Distribution Networks: A Real Options Approach

There is a growing concern about how the technical, managerial and financial capacity of drinking water systems can be sustained in the long run with future uncertainties. A water supply system is critical for the well- being of a community and it must provide water in sufficient quantity, of appropriate quality and without interruption. People have high expectations for the proper functioning of these systems but the future is uncertain and it is very difficult to conceive an infallible infrastructure. This work proposes a real options (ROs) approach that takes into account future uncertainty associated with water distribution networks. The ROs methodology extends traditional analysis to include flexible strategic implementation. This work describes a decision support methodology to design water networks that are adaptable over a long-term planning horizon. Representing design strategies as decision trees allows decision makers to easily adapt the system according to future circumstances. Results show that the ROs solution makes it possible to save on resources through an analysis based on an extended and uncertain planning horizon.