Assessing the risk posed by natural hazards to infrastructures

Abstract

Abstract. This paper proposes a model for assessing the risk posed by natural hazards to infrastructures, with a focus on the indirect losses and loss of stability for the population relying on the infrastructure. The model prescribes a three-level analysis with increasing level of detail, moving from qualitative to quantitative analysis. The focus is on a methodology for semi-quantitative analyses to be performed at the second level. The purpose of this type of analysis is to perform a screening of the scenarios of natural hazards threatening the infrastructures, identifying the most critical scenarios and investigating the need for further analyses (third level). The proposed semi-quantitative methodology considers the frequency of the natural hazard, different aspects of vulnerability, including the physical vulnerability of the infrastructure itself, and the societal dependency on the infrastructure. An indicator-based approach is applied, ranking the indicators on a relative scale according to pre-defined ranking criteria. The proposed indicators, which characterise conditions that influence the probability of an infrastructure malfunctioning caused by a natural event, are defined as (1) robustness and buffer capacity, (2) level of protection, (3) quality/level of maintenance and renewal, (4) adaptability and quality of operational procedures and (5) transparency/complexity/degree of coupling. Further indicators describe conditions influencing the socio-economic consequences of the infrastructure malfunctioning, such as (1) redundancy and/or substitution, (2) cascading effects and dependencies, (3) preparedness and (4) early warning, emergency response and measures. The aggregated risk estimate is a combination of the semiquantitative vulnerability indicators, as well as quantitative estimates of the frequency of the natural hazard, the potential duration of the infrastructure malfunctioning (e.g. depending on the required restoration effort) and the number of users of the infrastructure.Case studies for two Norwegian municipalities are presented for demonstration purposes, where risk posed by adverse weather and natural hazards to primary road, water supply and power networks is assessed. The application examples show that the proposed model provides a useful tool for screening of potential undesirable events, contributing to a targeted reduction of the risk.

Integrated risk assessment due to slope instabilities in the roadway network of Gipuzkoa, Basque Country

“…One of the major limitations for the quantitative risk assessment of roadways is the great data demand that it implies. The hazard in terms of probability of an event of a given magnitude requires extensive data on the frequency and also magnitude (volume) of the events (Fell et al, 2008;Jaiswal et al, 2010). Most commonly, landslide inventories are required (Dai et al, 2002;Ferlisi et al, 2012), although in most cases they are scarce.…”

“…A well-known example of semi-quantitative methods is the Rockfall Hazard Rating System (Pierson and Van Vickle, 1993) recommended by the FHWA (Federal Highway Administration of the United States), which was later adapted by Budetta (2004) specifically for rockfall risk along roads. The pure quantitative risk assessment (QRA), however, consists of the hazard assessment in terms of probability of failure or occurrence of an event of a given magnitude multiplied by its respective consequences (Fell et al, 2008), which is not treated by semiquantitative methods. Hungr et al (1999) quantified the rockfall risk along roadways in British Columbia after deriving magnitudecumulative frequency curves.…”

Integrated risk assessment due to slope instabilities at the roadway network of Gipuzkoa, Basque Country

“…Very few examples of roadway vulnerability exist in the literature (e.g. Mansour et al 2011;Eidsvig et al 2017). Their applicability or adjustment to other case-studies is a topic for further research.…”

Editorial to the special issue on resilience and vulnerability assessments in natural hazard and risk analysis

“…Given the conditions of global environmental change such as outlined in the Fifth Assessment Report of the United Nations Intergovernmental Panel on Climate Change (Stocker et al, 2013), impacts from natural hazards on natural and human systems are manifest worldwide (Keiler et al, 2010;Field et al, 2014). Such impacts are the result of both the frequency and magnitude of the hazard and the exposure of the society or elements at risk, such as buildings or infrastructure lines (Keiler and Fuchs, 2016), as well as underlying dynamics (e.g.…”

“…Based on case studies from Norwegian municipalities, Eidsvig et al (2017) propose a model for assessing the risk posed by natural hazards to infrastructure, with a focus on indirect losses and loss of stability for the population relying on the infrastructure. Focusing on a method for semi-quantitative analyses, a screening of possible scenarios of natural hazards threatening the infrastructure is performed, and the most critical scenarios are identified with respect to further quantitative assessment.…”