Lifeline Issue in Social Vulnerability Indexing: A Review of Indicators and Discussion of Indicator Application

The article reviews ways to improve measurements of lifeline vulnerability, defining lifeline vulnerability as aspects of social vulnerability to natural hazards influenced by lifeline failure. First, a literature review of indicators commonly used to address lifeline vulnerability within social vulnerability indexing is presented, in order to provide a theoretical basis for the study. Then, nine lifeline vulnerability indicators for central Norway are mapped to provide a practical basis. Thereafter, the author uses the theoretical and practical basis to discuss some problematic issues with respect to indicator selection. The review shows that to date assessments have addressed narrow segments of the broad range of factors influencing lifeline vulnerability. The map examples underscore that an indicator must be validated for each context, and that minor variations on the definition of a lifeline indicator is a critical process. Lifeline indicators represent life situations that conceptually stand apart from indicators representing social categories or exposure. Due to interdependencies among lifeline systems and because of the spatial irregularity of people's dependence on lifelines, it is difficult to determine both the spatial extent of outage and the social consequences. Further, because of lifeline vulnerability's distinct conceptual and spatial characteristics, the author suggests that it should be indexed separately from social factors, exposure, and risk. (C) 2014 American Society of Civil Engineers.