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Lookup NU author(s): David Alderson,
Professor Stuart Barr
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The failure of critical infrastructures can be far reaching, and detrimental not only to the nation’s economy, but to the health and wellbeing of the populace. The vulnerability of the UK’s national Infrastructure was dramatically highlighted during the summer of 2007 when instances of flooding caused damages to energy, water, and transportation assets resulting in an estimated cost of £3.6 billion. As well as direct damages associated with the flooding, indirect damages and disruptions where experienced through interdependencies between infrastructure sectors. Understanding the direct and indirect consequences of interdependent infrastructure failure is therefore important for providing decision makers with a more complete overview of the national infrastructure systems performance and reliability for a range of given hazards. Research in this area has grown steadily over the past few years, but often fails to accurately represent the spatial characteristics of both the hazard and downstream consequences. Recognising the need to capture the spatial characteristics of all elements within the failures causal chain, a methodology has been developed utilising a well-populated spatial database of the UK’s national infrastructure. Starting with a spatially coherent natural hazard, an algorithm is used to calculate the direct consequences of such a failure by intersecting the infrastructure assets located directly in the hazard area. Indirect consequences are then calculated through the implementation of a number of interdependency rules, which are stored within the database in an interdependency matrix. The indirect consequences brought about by demand (physical) interdependencies are used to produce a failure footprint. In order to estimate the downstream consequences of such failures; spatially explicit demographic data is allocated to supply nodes within the network. This approach facilitates the analysis of indirect economic consequences of failure and recovery at regional and national scales using an input-output modelling approach, which can be extended to consider long-term changes in the economy. This model has been implemented to analyse the risk to the UK’s infrastructure assets to extreme flood events, such as those seen in the summer of 2007. Where previous estimates have intersected the number of assets which are located directly in the floodplain – this study attempts to provide more realistic estimates of at-risk infrastructure by accounting for the indirect consequences arising through interdependent failures. Calculation of the indirect consequences is completed using a set of interdependency rules – whose mechanisms were derived from historical flood events. Extensions to this model are planned through the inclusion of spatially coherent probabilistic flood scenarios, a more accurate representation of failure through the use of infrastructure node fragility curves and coupling strengths, and finally a dynamic component; capable of analysing the time-dependent propagation of failure through system components.
Author(s): Thacker S, Henriques J, Hall J, Alderson D, Barr S
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: Network of Networks: Systemic Risk and Infrastructural Interdependencies
Year of Conference: 2012