Image is from page 29 of the Federal Emergency Agency's "Guidance for Flood Risk Analysis and Mapping, Flood Depth and Analysis Grids", February 2018. Document is available at https://www.fema.gov/media-library-data/1523562952942-4c54fdae20779bb004857f1915236e6c/Flood_Depth_and_Analysis_Grids_Guidance_Feb_2018.pdf Hovering over the image in the PDF documents caused a popup window that says, "An example of the percent annual chance of flooding over a 30-yr period grid is shown, with reds and oranges representing areas more likely to flood, and yellows and greens representing areas less likely to flood over a 30-yr time period."

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