Climate-related hazards (e.g. flooding & sea level rise currently)

Collection of hazard-related data -- FEMA flood and NOAA SLR

Contents

root

flood-hazard

Details

Visibility: Public
Owner: Carl Boettiger
Created: 25 Jul 2026
Last Updated: 25 Jul 2026

Analytics

Contents

Details

Analytics

Climate-related hazards (e.g. flooding & sea level rise currently)

Collection of hazard-related data -- FEMA flood and NOAA SLR

Contents

root

flood-hazard

Details

Visibility: Public
Owner: Carl Boettiger
Created: 25 Jul 2026
Last Updated: 25 Jul 2026

Analytics

28 days

Downloads

18,560

Data served

339 GB

Countries

28-day downloads

17 Jul 2026

13 Aug 2026

Analytics

README

FEMA National Flood Hazard Layer — Flood Hazard Zones (National)

Flood hazard zones (S_FLD_HAZ_AR) from FEMA's National Flood Hazard Layer (NFHL), the authoritative U.S. inventory of flood-risk areas delineated on effective Flood Insurance Rate Maps (FIRMs). National coverage compiled from FEMA's per-county effective-FIRM products and reprojected to OGC:CRS84.

Source: FEMA Flood Map Service Center / NFHL. Product index: https://hazards.fema.gov/femaportal/NFHL/searchResult.action; per-county products served at https://hazards.fema.gov/nfhlv2/output/County/<DFIRMID>_<date>.zip. Layer: S_FLD_HAZ_AR.
Coverage: 2,662 county products — all U.S. states, DC, and territories (PR, VI, GU, AS, MP). 5,631,998 polygons.
Geometry: simplified to ~10 m (ST_SimplifyPreserveTopology, 0.0001°) for this catalog layer — lossless at the H3 res-10 hex grid (~65 m cells), immaterial at display zooms. Full-precision per-county source zips are kept at s3://public-hazard/raw/county/.
License: public domain (U.S. federal government work, FEMA).

Files

Asset	S3 URL
GeoParquet	`https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.parquet`
PMTiles	`https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.pmtiles`
H3 hex (res 10)	`https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard/hex/h0=*/data_0.parquet`

Flood zone codes (`FLD_ZONE`)

Special Flood Hazard Areas — 1%-annual-chance ("100-year") flood, SFHA_TF = 'T':

Code	Meaning
`A`	1%-annual-chance floodplain, no base flood elevation (BFE)
`AE`	1%-annual-chance floodplain with BFE (`STATIC_BFE`)
`AH`	1%-annual-chance shallow flooding (ponding), 1–3 ft, with BFE
`AO`	1%-annual-chance shallow flooding (sheet flow), with average `DEPTH`
`A99`	1%-annual-chance area with flood-protection system under construction
`V`	1%-annual-chance coastal high-hazard (wave action), no BFE
`VE`	1%-annual-chance coastal high-hazard with BFE

Non-SFHA / other (SFHA_TF = 'F'):

Code	Meaning
`X`	Minimal/moderate hazard — outside the 1%-annual-chance floodplain. The 0.2% ("500-year") band is marked by `ZONE_SUBTY = '0.2 PCT ANNUAL CHANCE FLOOD HAZARD'`
`D`	Possible but undetermined flood hazard (no analysis performed)
`OPEN WATER`	Open-water areas
`AREA NOT INCLUDED`	Area not included in the FIRM study

ZONE_SUBTY carries the sub-classification (FLOODWAY, AREA OF MINIMAL FLOOD HAZARD, 0.2 PCT ANNUAL CHANCE FLOOD HAZARD, …). STATIC_BFE / DEPTH / VELOCITY use -9999 for N/A.

MapLibre GL JS

The PMTiles source-layer is flood-hazard:

DuckDB

H3 hex

One hex row = one (feature, cell) pair, keyed by fid. Per-feature attributes (STATIC_BFE, DEPTH, VELOCITY) are repeated on every cell a polygon covers — never SUM/AVG them across hex rows; dedup by fid first. Estimate the area of a zone from cell counts, not from a source attribute. FLD_ZONE / SFHA_TF / ZONE_SUBTY are safe to GROUP BY/filter.

Provenance

Merged from FEMA NFHL per-county S_FLD_HAZ_AR shapefiles (NAD83, EPSG:4269), reprojected to OGC:CRS84, simplified to ~10 m, written as DuckDB-native GeoParquet, tiled to PMTiles, and indexed to H3 (native resolution 10; parent resolutions 9, 8, 0) via the cng-datasets workflow. Source text fields truncated mid-multibyte in the FEMA DBFs were repaired to valid UTF-8.

Analytics

28 days

Downloads

18,560

Data served

339 GB

Countries

28-day downloads

17 Jul 2026

13 Aug 2026

README

FEMA National Flood Hazard Layer — Flood Hazard Zones (National)

Source: FEMA Flood Map Service Center / NFHL. Product index: https://hazards.fema.gov/femaportal/NFHL/searchResult.action; per-county products served at https://hazards.fema.gov/nfhlv2/output/County/<DFIRMID>_<date>.zip. Layer: S_FLD_HAZ_AR.
Coverage: 2,662 county products — all U.S. states, DC, and territories (PR, VI, GU, AS, MP). 5,631,998 polygons.
Geometry: simplified to ~10 m (ST_SimplifyPreserveTopology, 0.0001°) for this catalog layer — lossless at the H3 res-10 hex grid (~65 m cells), immaterial at display zooms. Full-precision per-county source zips are kept at s3://public-hazard/raw/county/.
License: public domain (U.S. federal government work, FEMA).

Files

Asset	S3 URL
GeoParquet	`https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.parquet`
PMTiles	`https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.pmtiles`
H3 hex (res 10)	`https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard/hex/h0=*/data_0.parquet`

Flood zone codes (`FLD_ZONE`)

Special Flood Hazard Areas — 1%-annual-chance ("100-year") flood, SFHA_TF = 'T':

Code	Meaning
`A`	1%-annual-chance floodplain, no base flood elevation (BFE)
`AE`	1%-annual-chance floodplain with BFE (`STATIC_BFE`)
`AH`	1%-annual-chance shallow flooding (ponding), 1–3 ft, with BFE
`AO`	1%-annual-chance shallow flooding (sheet flow), with average `DEPTH`
`A99`	1%-annual-chance area with flood-protection system under construction
`V`	1%-annual-chance coastal high-hazard (wave action), no BFE
`VE`	1%-annual-chance coastal high-hazard with BFE

Non-SFHA / other (SFHA_TF = 'F'):

Code	Meaning
`X`	Minimal/moderate hazard — outside the 1%-annual-chance floodplain. The 0.2% ("500-year") band is marked by `ZONE_SUBTY = '0.2 PCT ANNUAL CHANCE FLOOD HAZARD'`
`D`	Possible but undetermined flood hazard (no analysis performed)
`OPEN WATER`	Open-water areas
`AREA NOT INCLUDED`	Area not included in the FIRM study

ZONE_SUBTY carries the sub-classification (FLOODWAY, AREA OF MINIMAL FLOOD HAZARD, 0.2 PCT ANNUAL CHANCE FLOOD HAZARD, …). STATIC_BFE / DEPTH / VELOCITY use -9999 for N/A.

MapLibre GL JS

The PMTiles source-layer is flood-hazard:

DuckDB

H3 hex

Provenance

1map.addSource('flood-hazard', {
2  type: 'vector',
3  url: 'pmtiles://https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.pmtiles'
4});
5map.addLayer({
6  id: 'flood-hazard-fill',
7  type: 'fill',
8  source: 'flood-hazard',
9  'source-layer': 'flood-hazard',
10  paint: {
11    'fill-color': [
12      'match', ['get', 'FLD_ZONE'],
13      'AE', '#2b8cbe', 'A', '#74a9cf', 'AH', '#a6bddb', 'AO', '#bdc9e1', 'A99', '#d0d1e6',
14      'VE', '#d7301f', 'V', '#fc8d59',
15      'X', '#f0f0f0', 'D', '#dfdfdf', 'OPEN WATER', '#9ecae1',
16      '#cccccc'
17    ],
18    'fill-opacity': 0.6
19  }
20});

1map.addSource('flood-hazard', {
2  type: 'vector',
3  url: 'pmtiles://https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.pmtiles'
4});
5map.addLayer({
6  id: 'flood-hazard-fill',
7  type: 'fill',
8  source: 'flood-hazard',
9  'source-layer': 'flood-hazard',
10  paint: {
11    'fill-color': [
12      'match', ['get', 'FLD_ZONE'],
13      'AE', '#2b8cbe', 'A', '#74a9cf', 'AH', '#a6bddb', 'AO', '#bdc9e1', 'A99', '#d0d1e6',
14      'VE', '#d7301f', 'V', '#fc8d59',
15      'X', '#f0f0f0', 'D', '#dfdfdf', 'OPEN WATER', '#9ecae1',
16      '#cccccc'
17    ],
18    'fill-opacity': 0.6
19  }
20});

1INSTALL spatial; LOAD spatial;
2-- Special Flood Hazard Area polygons in a county (DFIRM_ID prefix = state+county FIPS)
3SELECT FLD_ZONE, ZONE_SUBTY, STATIC_BFE, geom
4FROM read_parquet('https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.parquet')
5WHERE SFHA_TF = 'T' AND DFIRM_ID LIKE '06037%';   -- Los Angeles County, CA

1INSTALL spatial; LOAD spatial;
2-- Special Flood Hazard Area polygons in a county (DFIRM_ID prefix = state+county FIPS)
3SELECT FLD_ZONE, ZONE_SUBTY, STATIC_BFE, geom
4FROM read_parquet('https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard.parquet')
5WHERE SFHA_TF = 'T' AND DFIRM_ID LIKE '06037%';   -- Los Angeles County, CA

1-- Approx SFHA area by H3 res-10 cell count, per state (h0 partition)
2SELECT h0, COUNT(DISTINCT h10) AS cells_res10
3FROM read_parquet('https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard/hex/h0=*/data_0.parquet')
4WHERE SFHA_TF = 'T'
5GROUP BY h0;

1-- Approx SFHA area by H3 res-10 cell count, per state (h0 partition)
2SELECT h0, COUNT(DISTINCT h10) AS cells_res10
3FROM read_parquet('https://s3-west.nrp-nautilus.io/public-hazard/flood-hazard/hex/h0=*/data_0.parquet')
4WHERE SFHA_TF = 'T'
5GROUP BY h0;

Climate-related hazards (e.g. flooding & sea level rise currently)

Climate-related hazards (e.g. flooding & sea level rise currently)

FEMA National Flood Hazard Layer — Flood Hazard Zones (National)

Files

Flood zone codes (FLD_ZONE)

MapLibre GL JS

DuckDB

H3 hex

Provenance

FEMA National Flood Hazard Layer — Flood Hazard Zones (National)

Files

Flood zone codes (FLD_ZONE)

MapLibre GL JS

DuckDB

H3 hex

Provenance

Flood zone codes (`FLD_ZONE`)

Flood zone codes (`FLD_ZONE`)