A Comprehensive Disaster Risk Index for the United States
MICHAEL E. SENN
Advisor: Dr. Susan L. Cutter
Risk to life, property, infrastructure and even environmental security emanate from a variety of hazard sources. Key to reducing risk is the ability to measure it and present it to decision-makers and stakeholders in a meaningful and understandable way. Currently, there exist no comprehensive hazard risk indices for the United States that have the ability to capture and convey a contemporary conceptualization of risk to hazards. Such an index, the World Risk Index, exists at the global level. The World Risk Index serves as an analogy for research on risk at various scales.
The purpose of this dissertation is to facilitate an increased awareness of risk and the different factors that contriburte to it and to provide a method for easily assessing risk at subnational scales. The following broad research questions frame this work: a) Can the World Risk Index be customized to a subnational scale in the United States? Which indicators are appropriate for use at the state and county level in the United States? b) Does the disaggregation of disaster risk to state and county scales provide more detailed understanding of the spatial distribution of risks and the componetns of risk? c) How does the risk assessment produced by a top-down approach compare to other US risk assessments at the county scale?
To answer these questions, this dissertation is focused on the development of a risk index, the United States Disaster Risk Index (USDRI), tailored to assess risk at various scales. The USDRI is a proof of concept, and uses the methodology and indicators of the aforementioned World Risk Index to establish a baseline for evaluating risk at the state and country level. The validity of the index is examined through explorator spatial statistical analysis. The results are also compared to loss data in order to assess whether the USDRI explains variability in losss. In addition, the USDRI and its components are compared to existing indices to determine similarities and differences.
The results indicate that the UsDRI provides new insight into risk at the state and county scale in the US. The ability to quickly tailor the index to various hazards of interest--to include potential hazards such as sea-level rise--proves to be one of its strongpoints. The USDRI, with some modification to the exposure component, shows the ability to explain variation in loss, especially at the state level. When compared to existing indices, USDRI risk and vulnerability show many similarities but also some important differences. For example, both the USDR vulnerability component and the established Social Vulnerability Index show clusters of lower vulnerability in the Northeast US, bu the USDRI shows large clusters of vulnerability in the Midwest whereas the Social Vulnerability Index does not. When the lessons learned are taken into consideration, the USDRI is successful in providing a baseline for the future evaluation of risk at the subnational level.