Two different physical processes

Inland flood risk in FEMA's National Risk Index covers riverine and flash flooding — rain and snowmelt overwhelming rivers, streams, and drainage. Coastal flood risk covers storm surge, pushed inland by hurricanes and nor'easters. They peak in different seasons, respond to different infrastructure (levees and drainage versus seawalls and elevation), and a county's exposure to one says little about its exposure to the other.

What pure coastal risk looks like

Virginia Beach city, VA and Beaufort County, SC carry real coastal storm-surge exposure while sitting nowhere near the top of the national list for inland river flooding — landlocked-adjacent risk simply doesn't apply to them, which this site records as "Not Applicable," not a zero score standing in for low risk.

Where both hazards matter at once

Los Angeles County, CA and Bergen County, NJ are among roughly 128 counties in this dataset where inland and coastal scores land within 10 points of each other — close enough that this site reports both rather than picking a dominant one arbitrarily. For a county like that, flood defense genuinely means two separate problems, not one.

Landlocked counties aren't being shortchanged

Roughly 2,644 of the 3144 counties in this dataset have no coastal exposure at all, correctly recorded as "Not Applicable" rather than a coastal score of zero — the distinction matters because a true zero would suggest FEMA evaluated coastal risk and found none, when in fact the hazard type simply doesn't apply inland.