United States Flood Hazard Zones and Insurance Rate Maps

The National Flood Hazard Layer (NFHL) provides digital flood hazard information for the United States, published by the Federal Emergency Management Agency (FEMA). It incorporates all Digital Flood Insurance Rate Map (DFIRM) databases and subsequent map revisions, classifying areas by 1-percent and 0.2-percent annual chance flood events.

Use Cases

• Model flood risk for property valuation by analyzing the 1-percent-annual-chance flood event and Special Flood Hazard Area (SFHA) classifications.
• Assess coastal versus riverine flooding exposure by comparing hazard zones within the Coastal Barrier Resources System (CBRS).
• Update municipal planning maps by integrating DFIRM and Letters Of Map Revision (LOMR) data to reflect current floodways and Base Flood Elevations.

Strengths

• Data is derived from official Flood Insurance Studies (FISs) and Flood Insurance Rate Maps (FIRMs) published by FEMA.
• Horizontal control specifications support mapping at a detailed scale of 1:12,000.
• Includes updates through Letters Of Map Revision (LOMRs) issued against the original DFIRM databases.

Limitations

• The dataset's last update was in December 2020, so it may not reflect the most recent flood hazard analyses or map revisions.
• Specific data volume metrics like row count, column count, and file size are unknown, making it difficult to assess computational requirements.

Provenance

Source

Federal Emergency Management Agency (FEMA).

Collection Method

Derived from Digital Flood Insurance Rate Map (DFIRM) databases, Flood Insurance Studies (FISs), FIRMs, and new mapping data.

Time Range

null

Freshness

Last updated on 2020-12-02.

Geography

United States, available as State or US Territory data sets.