Browsing by Author "Butler, David"

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    Animating inter-organisational resilience communication: a participatory social network analysis of water governance in the UK
    (CellPress, 2020-10-03) Ward, Sarah; Meng, Fanlin; Bunney, Sarah; Diao, Kegong; Butler, David
    Resilience as a concept and resilience assessment as a practice are being explored across a range of social, ecological and technical systems. In this paper, we propose a new method and visualisation approach for interrogating the communication of resilience within organisational networks, using participatory social network analysis and message passing. Through an examination of the UK water sector organisational network, represented by multiple co-produced network graphs, we identify organisations having a key role in the communication of resilience regulatory and evidence messages, as well as highlighting the potential role of complexity tools in strategy formulation. Animations are presented showing the dynamics of resilience communication, which is discussed. Reflections on the use of participatory social network analysis are explored, as the method opens new doors to potentially examine how network changes could alter communication. Key insights highlight that perceived responsibilities for resilience in the UK water sector rest with a small core of organisations; water customers play a limited role in the two-way communication of resilience and water sector organisations do not communicate widely on resilience with other sectors (such as energy). Additionally, who an organisations’ neighbours are and what catalyses a message to be passed are important in determining how quickly messages spread. Results lead to a recommendation that high level governmental and policy organisations should engage to a greater extent with new resilience knowledge and consider the use of complexity tools in policy making. Policy in relation to resilience is not keeping pace with such knowledge, limiting the communication and learning of organisations who ardently follow policy and regulation. For inter-organisational cooperation to make a difference to water governance, such organisations need to be encouraged to communicate and embed the latest approaches in relation to resilience and complexity thinking and practice.
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    Battle of Postdisaster Response and Restoration
    (ASCE, 2020-06-10) Paez, Diego; Filion, Yves; Quintiliani, Claudia; Santopietro, Simone; Sweetapple, Chris; Meng, Fanlin; Farmani, Raziyeh; Fu, Guangtao; Butler, David; Zhang, Qingzhou; Zheng, Feifei; Diao, Kegong; Ulanicki, Bogumil; Huang, Yuan; Deuerlein, Jochen; Gilbert, Denis; Abraham, Edo; Piller, Olivier; Bałut, Alicja; Brodziak, Rafał; Bylka, Jędrzej; Zakrzewski, Przemysław; Li, Yuanzhe; Gao, Jinliang; Jian, Cai; Ou, Chenhao; Hu, Shiyuan; Sophocleous, Sophocles; Nikoloudi, Eirini; Mahmoud, Herman; Woodward, Kevin; Romano, Michele; Santonastaso, Giovanni Francesco; Creaco, Enrico; Di Nardo, Armando; Di Natale, Michele; Bibok, Attila; Salcedo, Camilo; Aguilar, Andrés; Cuero, Paula; González, Sebastián; Muñoz, Sergio; Pérez, Jorge; Posada, Alejandra; Robles, Juliana; Vargas, Kevin; Franchini, Marco; Galelli, Stefano; Kim, Joong Hoon; Iglesias-Rey, Pedro; Kapelan, Zoran; Saldarriaga, Juan; Savic, Dragan; Walski, Thomas
    The paper presents the results of the Battle of Post-Disaster Response and Restoration (BPDRR), presented in a special session at the 1st International WDSA/CCWI Joint Conference, held in Kingston, Ontario, in July 2018. The BPDRR problem focused on how to respond and restore water service after the occurrence of five earthquake scenarios that cause structural damage in a water distribution system. Participants were required to propose a prioritization schedule to fix the damages of each scenario while following restrictions on visibility/non visibility of damages. Each team/approach was evaluated against six performance criteria that included: 1) Time without supply for hospital/firefighting, 2) Rapidity of recovery, 3) Resilience loss, 4) Average time of no user service, 5) Number of users without service for 8 consecutive hours, and 6) Water loss. Three main types of approaches were identified from the submissions: 1) General purpose metaheuristic algorithms, 2) Greedy algorithms, and 3) Ranking-based prioritizations. All three approaches showed potential to solve the challenge efficiently. The results of the participants showed that, for this network, the impact of a large-diameter pipe failure on the network is more significant than several smaller pipes failures. The location of isolation valves and the size of hydraulic segments influenced the resilience of the system during emergencies. On average, the interruptions to water supply (hospitals and firefighting) varied considerably between solutions and emergency scenarios, highlighting the importance of private water storage for emergencies. The effects of damages and repair work were more noticeable during the peak demand periods (morning and noontime) than during the low-flow periods; and tank storage helped to preserve functionality of the network in the first few hours after a simulated event.
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    Fractality in water distribution networks
    (figshare, 2017-09-01) Diao, Kegong; Butler, David; Ulanicki, Bogumil
    Fractals have been identified as a common feature of many natural and artificial systems that exhibit similar patterning at different scales. Understanding fractals is a critical aspect of decoding complex systems, as the pattern of such large systems can be revealed by identifying only a small part of the system. Furthermore, identify existing features of such systems can start at the large scale with the fewest details of the system under scrutiny before doing a more detailed analysis at finer scales. Such a process provides an efficient and reliable way of analysing and managing information of big data systems. This study revealed the fractality in water distribution networks (WDNs) based on research on fractals in complex networks. Specifically, we explored the existence of fractal patterns in six real world WDNs of different complexities (e.g. from a network with only 21 pipes to a network with 2465 pipes). The box-covering algorithm has been applied, which is the most widely used method to distinguish between fractal or non-fractal networks. The WDNs are first mapped into undirected graphs. Next, the method partitions the nodes into boxes of size lB, i.e. the maximal distance between nodes within each box is at most lB-1. By varying the box sizes, different minimum numbers of boxes NB required to cover the entire network can be identified. A network is fractal if the regression line for log(NB) and log(lB) is linear. The results demonstrate the existence of fractal patterns in all case study WDNs, as linear regression lines with coefficient of determination over 0.95 (R^2>0.95) are obtained in all analyses. As further verification, the self-similarity on multiscales is revealed, i.e. the similarity in patterns of component criticality. Based on the fractal patterns, a systematic method is also developed for more efficient identification of critical pipes in WDNs, e.g. reducing the computational load by 61% in the case study.
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    Fractality in Water Distribution Networks: Application to Criticality Analysis and Optimal Rehabilitation
    (Taylor and Francis, 2021-07-08) Diao, Kegong; Butler, David; Ulanicki, Bogumil
    Fractals have been identified as a common feature in many natural and artificial networks that exhibit self-similarity of the topological patterns, i.e. different parts of the system have similar structures to each other as well as to the whole system. This study investigates the fractality in water distribution networks (WDNs) and the application of the fractal property in WDNs analysis. Specifically, we explore the existence of fractal topological patterns in eight real-world WDNs of different complexities by using the box-covering algorithm. The results demonstrate all of the studied WDNs are fractal. Moreover, the application of the fractal property is demonstrated via critical pipe identification and optimal rehabilitation of benchmark real-world WDNs. All results show that the fractal-based approach can achieve better or equally good solutions compared with conventional methods in a much more efficient way, e.g. via automation of some processes or significant reduction in the search space/components to consider.
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    Global resilience analysis of water distribution systems
    (Elsevier, 2016-10-04) Diao, Kegong; Sweetapple, Chris; Farmani, Raziyeh; Fu, Guangtao; Ward, Sarah; Butler, David
    Evaluating and enhancing resilience in water infrastructure is a crucial step towards more sustainable urban water management. As a prerequisite to enhancing resilience, a detailed understanding is required of the inherent resilience of the underlying system. Differing from traditional risk analysis, here we propose a global resilience analysis (GRA) approach that shifts the objective from analysing multiple and unknown threats to analysing the more identifiable and measurable system responses to extreme conditions, i.e. potential failure modes. GRA aims to evaluate a system's resilience to a possible failure mode regardless of the causal threat(s) (known or unknown, external or internal). The method is applied to test the resilience of four water distribution systems (WDSs) with various features to three typical failure modes (pipe failure, excess demand, and substance intrusion). The study reveals GRA provides an overview of a water system's resilience to various failure modes. For each failure mode, it identifies the range of corresponding failure impacts and reveals extreme scenarios (e.g. the complete loss of water supply with only 5% pipe failure, or still meeting 80% of demand despite over 70% of pipes failing). GRA is also able to illustrate the similarities or differences in responses of different systems to various failure modes. Moreover, GRA reveals that increased resilience to one failure mode may decrease resilience to another and the same fraction of component failure could result in tremendously different level of failure impacts. The method can be used as a comprehensive diagnostic framework to evaluate a range of interventions for improving system resilience in future studies.
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    Modular interdependency analysis for water distribution systems
    (Elsevier, 2021-06-02) Diao, Kegong; Jung, Donghwi; Farmani, Raziyeh; Fu, Guangtao; Butler, David; Lansey, Kevin
    Complexity in water distribution systems (WDSs) poses a challenge for analysis and management of the systems. To reduce the complexity, the recent development of complex network science provides a system decomposition technique that converts a complex WDS with a large number of components into a simple system with a set of interconnected modules. Each module is a subsystem with stronger internal connections than external connections. Thus far, the topological features of the modular structure in WDS have been extensively studied but not the behavioural features, e.g. the hydraulic interdependencies among modules. Therefore, this paper aims to quantitatively measure and graphically visualize the module interdependency in WDSs, which helps understanding the behavioural complexity of WDSs and thus various WDS analyses, such as pipe maintenance, model calibration, rehabilitation, and District Metered Areas planning. Specifically, this study first identifies the WDS’s modular structure then measures how changes in the state of one module (i.e. any single pipe failure or perturbed demand within each module) affect the state of another module. Modular interdependencies are summarized in an interdependency matrix and visualized by the digraph. Four real-world systems are analysed, and three of them shows low interdependencies among most of the modules and there are only a few critical modules whose status changes will substantially affect a number of other modules. Hence, highly interconnected topologies may not result in strong and complex module interdependency, which is a fact that simplifies several WDS analysis for practical applications as discussed in this paper.
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    Optimal Rehabilitation of Water Distribution Systems using a Cluster-based Technique
    (ASCE, 2017-03-20) Muhmmed, Karwan; Farmani, Raziyeh; Behzadian, Kourosh; Diao, Kegong; Butler, David
    Optimal rehabilitation of large water distribution system (WDS) with many decision variables, is often time-consuming and computationally expensive. This paper presents a new optimal rehabilitation methodology for WDSs based on graph theory clustering concept. The methodology starts with partitioning the WDS based on its connectivity properties into a number of clusters (small sub-systems). Pipes which might have direct impact on system performance are identified and considered for rehabilitation problem. Three optimisation-based strategies are then considered for pipe rehabilitation in the clustered network: 1) rehabilitation of some of the pipes inside the clusters; 2) rehabilitation of pipes in the path supplying water to the clusters; 3) combination of strategies 1 and 2. In all optimisation strategies, the decision variables for rehabilitation problem are the diameters of duplicated pipes; the objective functions are to minimise the total cost of duplicated pipes and to minimise the number of nodes with pressure deficiency. The performance of proposed strategies was demonstrated in a large WDS with pressure deficiencies. The performance of these strategies were also compared to the full search space optimisation strategy and engineering judgement based optimisation strategy in which all pipes and selection of pipes are considered as decision variables respectively. The results show that strategy 3 is able to generate solutions with similar performance that are cheaper by around 53% and 35% in comparison with the full search space and engineering judgement based optimisation strategies respectively. The results also demonstrate that the cluster-based approach can reduce the computational efforts for achieving optimum solutions compared to the other optimization strategies.
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    Reliable, resilient and sustainable water management: the Safe & SuRe approach
    (Wiley Online Library, 2017-06-17) Butler, David; Ward, Sarah; Sweetapple, Chris; Astaraie‐Imani, Maryam; Diao, Kegong; Farmani, Raziyeh; Fu, Guangtao
    Global threats such as climate change, population growth, and rapid urbanization pose a huge future challenge to water management, and, to ensure the ongoing reliability, resilience and sustainability of service provision, a paradigm shift is required. This paper presents an overarching framework that supports the development of strategies for reliable provision of services while explicitly addressing the need for greater resilience to emerging threats, leading to more sustainable solutions. The framework logically relates global threats, the water system (in its broadest sense), impacts on system performance, and social, economic, and environmental consequences. It identifies multiple opportunities for intervention, illustrating how mitigation, adaptation, coping, and learning each address different elements of the framework. This provides greater clarity to decision makers and will enable better informed choices to be made. The framework facilitates four types of analysis and evaluation to support the development of reliable, resilient, and sustainable solutions: “top-down,” “bottom-up,” “middle based,” and “circular” and provides a clear, visual representation of how/when each may be used. In particular, the potential benefits of a middle-based analysis, which focuses on system failure modes and their impacts and enables the effects of unknown threats to be accounted for, are highlighted. The disparate themes of reliability, resilience and sustainability are also logically integrated and their relationships explored in terms of properties and performance. Although these latter two terms are often conflated in resilience and sustainability metrics, the argument is made in this work that the performance of a reliable, resilient, or sustainable system must be distinguished from the properties that enable this performance to be achieved.