Mapping vulnerability in Arlington County, Virginia
SeanPavonePhoto via Getty Images
Local leaders last month released the Community Vulnerability Index Map, which uses various data points to find vulnerable populations and inform where resources should be allocated.
Policymakers, residents, developers and anyone else with an interest in Arlington County, Virginia, can now use a new tool to better identify pockets of vulnerable populations there.
The Community Vulnerability Index Map, which the county released last month, ranks census tracts from the highest to lowest concentrations of vulnerable populations, partly by using geographic information systems mapping and analytics.
“We’re advising that this should be part of an analysis, this should be your driver,” said Elizabeth Hardy, principal planner and demographer at Arlington County’s Department of Community Planning, Housing and Development. “Start with this, overlay your data points, look at where your programs are or where you want to change policy.”
To build CVIM, county staff analyzed several variables of vulnerability that they determined to be most relevant to Arlington’s residents. Those include race, age (younger than 18 and older than 65), income by household and individual, linguistic isolation (non-English speakers), education, and whether someone was born in a foreign country.
“Then we calculate a disparity score for each of those measures,” Hardy said. The county then ultimately gets percentile rankings that inform priority categories.
The result is that when users click on a tract on the color-coded map, a pop-up shows the overall vulnerability index ranking, from lowest to highest, and the ranking for each variable. Clicking “View Additional Details” pulls up just that: exact numbers, such as how many people are older than 65.
“We have it in ACMaps, which is where you can look at most of the county’s [geographic information system] data,” Hardy said. “What’s nice about this is that you can draw on here. You can make your own map. You can also upload your own data, so if you have data points that you want to overlay, you can do that here. If you want to put on other county data, you can do that, too.”
CVIM, built mainly with ArcGIS Pro from mapping software company Esri and Microsoft Excel, is also available as an application that has two tabs: Vulnerability Index and Demographics. The former lets users overlay data from other county initiatives to see how they are playing out in vulnerable areas. For instance, with a click, users can see where affordable housing units are located in relation to populations with high levels of need.
The Demographics tab gives the tract’s total population and percentages based on the variables, rather than rankings. “This is a really handy tool for folks that don’t have GIS experience,” Hardy said.
All of the CVIM data is open and available for public use via the county’s open data portal. What’s more, CVIM is designed to work alone or in tandem with the county’s Race and Ethnicity Dashboard and the Census Tracts Demographic Dashboard.
“The CVIM really merges these two together and looks at vulnerable populations in Arlington and what that means,” Hardy said.
Because CVIM is only a month old, Hardy said she doesn’t yet know how it’s being used internally by the county or externally by the public yet. Some use cases she envisions include understanding where to focus outreach — “It gives you more of an idea of who to reach out to,” Hardy said — and for the public to understand their community.
The next phase of the project, which she hopes to kick off soon, will be to “break down the demographic information into more disaggregate data,” Hardy said.
“We are hoping that we can click on the census tract and then have the whole profile of the age distribution, not just those under 18 and over 65,” she added. “You’ll see the breakout for every age group. You’ll see the breakout for every race.”
Arlington County isn’t alone in its use of GIS to serve the public good. Neighboring Fairfax County has a similar vulnerability index, for instance, and Jefferson County, Colorado, uses GIS in the form of the Food Systems Access and Analysis Tool to identify and offer help to food-deprived areas and demographic groups.
At the state level, California’s Office of Environmental Health Hazard Assessment uses CalEnviroScreen to pinpoint areas with high pollution levels and vulnerable populations, while Oregon has a Social Equity Index Map for prioritizing investments in high-disparity communities.
The county plans to continue to update CVIM depending on the feedback that comes in. For instance, they expect to add more data overlays.
“We’re always open to modifying what we have to really meet the public’s needs,” Hardy said.
NEXT STORY: New bill would loosen various BEAD rules