Identifying Critical Isolation Valves in a Water Distribution Network: A Socio-Technical Approach

Abstract Isolation valves are critical for reliable functioning of water distribution networks (WDNs). However, it is challenging for utilities to prioritize valve rehabilitation and replacement given it is often unclear if certain valves are operable in a given WDN. This study uses the Gomory-hu tree of the segment-valve representation (or dual representation) of WDNs to obtain logical implications of inoperable valves (i.e., which segments would be isolated and merged unnecessarily due to valve inoperability). Multi-objective optimization is then used to identify the critical valves based on selected attributes (e.g., social vulnerability, flow volume) of segments that would be unnecessarily isolated as a result. This study developed three multi-objective formulations: first, deterministic; second, accounting for uncertainty; and third, accounting or both uncertainty and likelihood of failure of pipes within segments. Identified critical valves are compared between the three developed formulations and a method considering only a single objective. Results demonstrated that the multi-objective optimization provided additional information that can be used to discern valve importance for utilities in comparison with using a single objective. Further, though there was overlap between the results from the three formulations, the third formulation provided the most insight without overwhelming decision-makers with a large number of identified valves.

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A New Method for Optimization of Water Distribution Networks While Considering Accidents

Water ◽

10.3390/w13121651 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1651

Author(s):

Ruizhe Liu ◽

Fangcheng Guo ◽

Weiqian Sun ◽

Yue Wang ◽

Zihan Zhang ◽

...

Keyword(s):

Optimization Model ◽

Annual Cost ◽

Water Distribution ◽

Water Distribution Network ◽

Distribution Networks ◽

Optimization Models ◽

Multi Objective Optimization ◽

Water Head ◽

Accident Conditions ◽

Single Objective

Optimization of water distribution networks can effectively reduce their annual cost, which includes the average investment for each year the operational costs and depreciation costs. However, the existing optimization models rarely directly consider the basic flow of each node in case of accidents, such as pipe bursts. Therefore, it is necessary to check the flow requirements under accident conditions. In order to deal with these drawbacks, two optimization models are established considering accident conditions: a single-objective optimization model considering annual cost as an economic objective, and a multi-objective optimization model with a reliability objective defined by the surplus water head. These models are solved based on the genetic algorithm, non-dominated sorting genetic algorithm-II algorithm and Levenberg-Marquardt iterative method. Applying two cases of a single pump station and a multi pump water station water supply, it is shown that the annual cost when considering the accident conditions is higher than that without considering the accident conditions. Moreover, the annual cost obtained with the multi-objective optimization model is slightly higher than that obtained with the single-objective optimization model. The cost is higher because the former model reduces the average surplus water head, which can improve the water distribution network reliability. Therefore, the model and optimization algorithm proposed in this paper can provide a general and fast optimization tool for water distribution network optimization.

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Multi-objective optimization for improving equity and reliability in intermittent water supply systems

Water Science & Technology Water Supply ◽

10.2166/ws.2020.066 ◽

2020 ◽

Vol 20 (5) ◽

pp. 1592-1603 ◽

Cited By ~ 1

Author(s):

Passwell Pepukai Nyahora ◽

Mukand Singh Babel ◽

David Ferras ◽

Andres Emen

Keyword(s):

Decision Making ◽

Water Supply ◽

Water Distribution ◽

Investment Decision ◽

Water Distribution Network ◽

Distribution Networks ◽

Water Supply Systems ◽

Multi Objective Optimization ◽

Multi Objective ◽

Intermittent Water Supply

Abstract Intermittent water systems suffer from several drawbacks such as unfair distribution among users, low reliability and poor water quality. Given limited water and financial resources, making decisions for improving intermittent water supply (IWS) becomes a complex process. The paths to continuous supply are a priori undefined, however, the provision of efficient service is crucial. In the scientific literature, limited research addresses how to improve intermittent systems, to enhance the current service while transitioning to continuous supply. A multi-objective optimization (MOO) tool using a genetic algorithm has been developed to assist in investment decision-making. This approach uses multiple cost-effective intervention options to maximize equity and reliability while minimizing cost implications in an IWS system. The costs in such interventions include expenditure on pipe replacement, booster pump and elevated tank installation. The approach was first tested on a benchmark Hanoi synthetic network, and then applied to the water distribution network of Milagro (Ecuador). The developed tool reveals the extent to which equity and reliability can be driving objectives, and how they can be factored into decision-making. The application of the MOO tool in intermittent systems in order to improve existing distribution networks with strategic infrastructure addition can provide greater equity and reliability.

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