Another important element of the risk assessment is identifying any particularly vulnerable populations in the community. The consequences of a disaster event extend well beyond physical damages, often causing or amplifying human suffering, economic loss, and social disruption. This is especially true for those who may not easily access the resources typically offered to assist with individual actions before, during, or after an emergency or disaster event.
These vulnerable populations may include children, the elderly, the physically or mentally disabled, non-English speakers, or the medically or chemically dependent. They may include those in low-to-moderate income households with limited mobility or means to pay for personal protections such as insurance or other risk mitigation activities, and even more limited means to cover disaster losses. They may also include transient populations such as students, homeless, migrant farm workers, and visitors that may be less familiar with local hazards and less prepared to protect themselves during an event.
A variety of data sources are available to help collect and assess the demographic and socioeconomic characteristics of people within the community, particularly statistical data provided by the U.S. Census Bureau at the tract, block group, and block levels. Similar to the way in which data on buildings, infrastructure, and critical facilities are used to assess the potential exposure of physical assets to hazard risks, census data can be used to identify and analyze vulnerable populations. Although methods vary, one widely recognized and replicated approach is the Social Vulnerability Index (SoVI®) developed by the University of South Carolina’s Hazards & Vulnerability Research Institute. The index is a comparative metric that synthesizes 30 variables, primarily from census data, that research suggests contribute to increased social vulnerability. An example of a Colorado application of the SoVI® technique is shown below.
Using the Social Vulnerability Index, the Colorado Division of Water Resources Dam Safety Branch conducted a Colorado social vulnerability analysis at the census-tract level. Local socioeconomic and demographic data were used to identify spatial patterns in social vulnerability across the state and have been applied to the hazards identified in the Colorado Natural Hazards Mitigation Plan. The tan and red areas reflect higher social vulnerability, and the yellow and blue areas reflect lower social vulnerability. Source - Colorado Natural Hazards Mitigation Plan (2013)
Regardless of the approach, the outcome of assessing vulnerable populations should be the identification of people most susceptible to harm and loss from hazards, as well as information that can be used to reduce vulnerability. In addition to resident locations, facilities that house or support people with functional needs such as medical care facilities, nursing homes, daycares, and others should be considered. Whether through illustrative maps, data tables, or simply a listing of particular locations or segments of the population, the objective is to ensure that specific vulnerabilities are incorporated in the risk assessment and addressed in the mitigation strategy.