Our team often meets with floodplain managers looking to leverage flood risk insight to conduct better outreach, plan dynamically for emergencies, and distribute resources more intelligently. Drawing links between sociodemographics, economics, and flood exposure to develop a holistic understanding of residents living in floodplains is core to these goals. While effective floodplain management is dependent on these linkages, making these connections is not always easy.
If you’re thinking about bringing additional data into your floodplain programs to inform your work, you might find it helpful to start with data from the U.S. Census Bureau. Census data is widely available, easily accessed online, and used by local governments throughout the country. Below we outline how you can mobilize these federal datasets to enrich your floodplain programs.
Integrating community census data analysis into your floodplain programs can help you...
You can access census information online using the Census Bureau’s Data Explorer. Through the explorer, data is searchable by topic (such as housing) or by geographic unit. It’s a large amount of information, so it can be difficult to know how to begin. The easiest first step would be to search for data for your specific region to see what’s available. Every census dataset has a geographic unit identifier (county, census tract, block etc.). To visualize the data in a mapping software such as QGIS or ArcMap, you can join the census data to one of these geographic boundary shapefiles based on the geographic unit identifier. Learn more about accessing the data and the different datasets available here.
As you’re diving into the data, you’ll need to hone in on which fields are relevant for your uses. This might be a tricky task, because there’s a lot of it! For floodplain management in particular, you’ll probably be interested in fields like population count, population growth, age distribution, median household income, income levels, race, and ethnicity. Digging deeper, you might find additional fields that are able to describe your community more precisely and provide greater insight. Some that might be of interest are: accessibility to public transit, unemployment rates, residential units occupied by an owner versus a renter, and education levels.
Once you identify the data fields most relevant for your community, FMPs are a good place to start using census data in your work. To get you started, here are a few ideas for analysis and integration of census information in FMPs:
As you utilize census data to inform FMPs and your floodplain management practices, it’s important to keep in mind some limitations of federal demography. Data available through the American Community Survey (ACS) is based on samples and estimates. As such, it has the potential to misrepresent a community. Error values are available for most data points in the ACS. This can help you evaluate accuracy. In general, much of the data available through the Census Bureau is presented as an average or median value for a predefined area (such as a census tract or block). If there’s a large variance within that area, the data point might be misleading. This article describes how measuring values based on varying geographic boundaries might significantly affect the result data.
Lastly, not all population groups are equally represented in census data. Historically, communities of color and marginalized populations have been critically underrepresented in census-taking. Because census data is widely used for decision-making across government scales and agencies, undercounting over time has contributed to imbalances in funding, investment, and resource distribution throughout the country.
This blog post was written by our former data analysis intern, Kama Lee-Tal! Have questions about integrating census data into your floodplain management work? Send us an email, we'd love to chat.
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