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Reasons for occasional, random pipe bursts in water distribution networks (WDNs) might come from numerous factors (e.g. pH value of the soil, the pipeline material). Still, the isolation of the damaged section is inevitable. While the corresponding area is segregated by closing the isolation valves, there is a shortfall in drinking water service. This paper analyses the vulnerability of segments of WDNs from the viewpoint of the consumers that is the product of the failure rate and the relative demand loss. Real pipe failure database, pipe material and pipe age data are used to increase the accuracy of the failure rate estimation for 27 real-life WDNs from Hungary. The vulnerability analysis revealed the highly exposed nature of the local vulnerabilities; the distribution of local vulnerability values follows a power-law distribution. This phenomenon is also found by investigating the artificial WDNs from the literature using N rule in terms of isolation valve layout, namely the ky networks, with similar results.

One of the basic infrastructures of every settlement is the water distribution system, which provides clean and potable water for both private houses, industrial consumers and institution establishments. The operational robustness and vulnerabilities of these networks is an essential issue, both for the quality of life and for the preservation of the environment. Even with frequent and careful maintenance, unintentional pipe bursts might occur, and during the reparation time, the damaged section must be isolated hydraulically from the main body of the water distribution network. Due to the size and complexity of these networks, it might not be trivial how to isolate the burst section, especially if one wishes to minimize the impact on the overall system. This paper presents an algorithmic method that is capable of creating isolation plans for real-life networks in a computationally efficient way, based on the graph properties of the network. Besides this segmentation plan, the topological behavior of the structural graph properties was analyzed with the help of the complex network theory to create a method for the quantitative topology based categorization of the water distribution networks.

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Purpose: Occasional, random pipe bursts are inevitable in water distribution networks; thus, the proper operation of isolation valves is critical. The damaged segment is segregated using the neighbouring valves during shutdown, causing the smallest isolation possible. This study analyses the importance of isolation valves individually from the perspective of the demand shortfall increment. Methods: An in-house, open-source software called STACI performs demand-driven simulations to solve the hydraulic equations with pressure-dependent demand determining the nodal pressures, the volumetric flow rates, and the consumption loss. The system has an additional consumption loss if an isolation valve cannot be closed. The criticality of an isolation valve is the increment in the relative demand shortfall caused by its malfunction. Moreover, centrality indices from complex network theory are applied to estimate the criticality without the need for computationally expensive hydraulic simulations. Results: The distribution of criticality values follows a power-law trend, i.e. some of the isolation valves have significantly higher importance during a shutdown. Moreover, Spearman's rank correlation coefficients between the centrality and criticality values indicate limited applicability. Conclusion: The criticality analysis can highlight which isolation valves have higher importance during reconstruction planning or maintenance. The Katz and the Degree centrality show a moderate positive correlation to the criticality, i.e., if numerous hydraulic simulations are not feasible, these quantities give an acceptable estimation.