Preprints
https://doi.org/10.5194/nhess-2020-371
https://doi.org/10.5194/nhess-2020-371

  14 Nov 2020

14 Nov 2020

Review status: a revised version of this preprint was accepted for the journal NHESS and is expected to appear here in due course.

Indirect flood impacts and cascade risk across interdependent linear infrastructures

Chiara Arrighi1, Maria Pregnolato2, and Fabio Castelli1 Chiara Arrighi et al.
  • 1Department of Civil and Environmental Engineering, University of Firenze, Florence, Italy
  • 2Department of Civil Engineering, University of Bristol, Bristol, UK

Abstract. Floods are the most frequent and damaging natural threat worldwide. Whereas the assessment of direct impacts is well advanced, the evaluation of indirect impacts is less frequently achieved. Indirect impacts are not due to the physical contact with flood water but result from the reduced performance of infrastructures. Linear critical infrastructures (such as roads and pipes) have an interconnected nature that may lead to failure propagation, so that impacts extend far beyond the inundated areas and/or period. This work presents the risk analysis of two linear infrastructure systems, i.e. the water distribution system (WSS) and the road network system. The evaluation of indirect flood impacts on the two networks is carried out for four flooding scenarios, obtained by a coupled 1D-quasi 2D hydraulic model. Two methods are used for assessing the impacts on the water distribution system and on the road network, a Pressure-Driven Demand network model and a transport network disruption model respectively. The analysis is focused on the identification of: (i) common impact metrics; (ii) vulnerable elements exposed to the flood; (iii) similarities and differences of the methodological aspects for the two networks; (iv) risks due to systemic interdependency. The study presents an application to the metropolitan area of Florence (Italy). When interdependencies are accounted for, results showed that the risk to the WSS in terms of Population Equivalent (PE/year) can be reduced by 71.5 % and 41.8 %, if timely repairs to the WSS stations are accomplished by 60 and 120 minutes respectively; the risk to WSS in terms of pipes length (km/year) reduces by 53.1 % and 15.6 %. The study highlights that resilience is enhanced by system risk-informed planning, which ensures timely interventions on critical infrastructures; however, temporal and spatial scales are difficult to define for indirect impacts and cascade effects. Perspective research could further improve this work by applying a system-risk analysis to multiple urban infrastructures.

Chiara Arrighi et al.

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Chiara Arrighi et al.

Chiara Arrighi et al.

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Short summary
Floods may affect critial infrastructure which provide essential services to people. In this work we analyse the impact of flood on road network and water supply system and we investigate how cascade effects propagate if interdepencies among networks are not considered. The analysis shows that if preparedness plans include information on accessibility to key sections of water supply plant less people suffer of water shortage in case of flood. The method is tested in the city of Florence (Italy).
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