Hurricane Katrina made landfall in New Orleans, Louisiana, at 6:10 a.m., Central Time, on August 29, 2005. Most of the city’s residents had already evacuated by that time, but according to Smithsonian Magazine, “about 150,000 people, largely low-income or disabled residents, remained.” It has been estimated that 986 of those who stayed lost their lives, more than 50% of the total fatalities from the storm. Those who survived, the magazine goes on to say, “lived in squalid conditions in the weeks and months following the storm,” with tens of thousands of people stranded without access to electricity or potable water.”
As these quotes reveal, the impacts of disasters, be they natural or human-caused, aren’t shared equally. Often, it‘s the people living in the poorest and most vulnerable communities who bear a disproportionate amount of the burden and take the longest to recover.
The degree to which a community can minimize human suffering or cope with the impact of a disaster is often associated with certain social conditions, including poverty and other socioeconomic factors, housing characteristics, and disability status. And when considered in sum, these factors characterize a community’s social vulnerability. To help public health officials and emergency response planners assess social vulnerability across the United States, the Geospatial Research, Analysis, & Services Program (GRASP) of the Centers for Disease Control and Prevention’s (CDC) Agency for Toxic Substances and Disease Registry created the CDC Social Vulnerability Index (SVI), which locates and ranks communities that will most likely need support before, during, and after a hazardous event.
The SVI ranks the vulnerability of every U.S. census tract (i.e., subdivisions of counties for which the U.S. Bureau of the Census collects statistical data) on 15 social factors, including unemployment, minority status, and disability, associated with one of four themes: Socioeconomic, Household Composition and Disability, Minority Status and Language, and Housing Type and Transportation. Each tract is then given a ranking for each theme and overall vulnerability.
Now, NASA’s Socioeconomic Data and Applications Center (SEDAC) has released a U.S. Social Vulnerability Index Grids dataset offering gridded layers for the CDC SVI data. The dataset is based on inputs at the census-tract level for each of the CDC’s 15 social vulnerability variables for the years 2000, 2010, 2014, 2016, and 2018, and aligns with SEDAC′s Gridded Population of the World (GPW) dataset, which is based on detailed U.S. Census geography.
“The primary use of the dataset is the ability to return SVI values for user-defined areas instead of being constrained by the tract-level geographies of the original data set,” said Dr. Alex de Sherbinin, Deputy Manager at SEDAC.
SEDAC, which is hosted at Columbia University’s Center for International Earth Science Information Network (CIESIN), is the NASA Earth Observing System Data and Information System (EOSDIS) Distributed Active Archive Center (DAAC) responsible for archiving and distributing socioeconomic data in the EOSDIS collection. SEDAC synthesizes Earth science and socioeconomic data and serves as an “information gateway” for a wide range of decision makers and other applied users.
According to Dr. Carolynne Hultquist, developer of SEDAC’s U.S. Social Vulnerability Index Grids dataset and postdoctoral research scientist at CIESIN, the U.S. Social Vulnerability Index Grids dataset was created to enhance the CDC’s SVI census tract dataset.