Mapping Those Most At Risk

by | Aug 24, 2022

When planning for climate disaster, many federal agencies assess risk on the scale of cities and counties. But in reality, neighborhoods within a city are impacted very differently from one another. A flood that hits Bayview-Hunters Point in San Francisco would pummel a dense, 96% minority community with a poverty rate nearly three times as high as the county average. That same flood in the Marina District would encounter a spread-out, predominantly white, and highly educated population with an average salary nearly ten times greater than Bayview-Hunters Point’s — making the area far  more able to withstand the flood and bounce back.

With the National Oceanic and Atmospheric Administration’s recent update to their long-running Billion Dollar Disaster Map, urban planners and citizens can see for themselves how disaster risk and vulnerability vary at the much finer “census tract” scale, representing about 4,000 people in a geographic area. Using the tool to look at “hazard risk” and “social vulnerability,” one can see how frontline communities like San Jose’s Alviso, Marin City, the San Rafael Canal District, East Oakland, and others stand out in stark contrast to the wealthier, whiter neighborhoods around them. The tool shows which census tracts have a significant number of people with characteristics that contribute to social vulnerability — for instance, those without vehicles, senior citizens, or the mobility-challenged. Or race, income, and educational level, which correlate with lower access to essential government programs and services that are essential to helping people and communities rebuild after a disaster. 

Map of the Bay Area color-coded to show proportion of people below the poverty line.

As risk maps go — and there are an overwhelming number out there — NOAA’s is still a little clunky. The census tract view is hidden in a drop-down menu above and to the right of the map, and to look at historic flood hazard risk one has to manually de-select all six other hazard types. The Bay Conservation and Development Commission’s regional Community Vulnerability map is even more granular, analyzing vulnerability at the small “census block” scale (geographic areas of 3,000 people or less), and it also indicates contamination exposure. But hopefully NOAA’s update represents progress toward seeing pre-existing risk and vulnerability disparities within a city or county, and taking ameliorative steps before the next disaster exposes and widens them. 

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About The Author

Isaac Pearlman

covers sea level rise, flooding, and other topics around the San Francisco Bay Area. His stories and essays have been featured in Sierra Magazine, Earth Island Journal, Estuary News, and the Progressive Populist, among other outlets.