The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by
FEMA, and any Letters Of Map Revision (LOMRs) that have been issued against those databases since their publication date.
The DFIRM Database is the digital, geospatial version of the flood hazard information shown on the published paper Flood Insurance
Rate Maps(FIRMs). The primary risk classifications used are the 1-percent-annual-chance flood event, the 0.2-percent-annual-chance
flood event, and areas of minimal flood risk. The NFHL data are derived from Flood Insurance Studies (FISs), previously published
Flood Insurance Rate Maps (FIRMs), flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data
where available. The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). The specifications for
the horizontal control of DFIRM data are consistent with those required for mapping at a scaleof 1:12,000. The NFHL data contain
layers in the Standard DFIRM datasets except for S_Label_Pt and S_Label_Ld. The NFHL is available as State or US Territory
data sets. Each State or Territory data set consists of all DFIRMs and corresponding LOMRs available on the publication date
of the data set.
Citation
Title Flood Hazard Area
publication Date
2009-08-03T00:00:00
cited responsible party
-
originator
organisation Name
Federal Emergency Management Agency
cited responsible party
-
publisher
organisation Name
Federal Emergency Management Agency
other Citation Details
Cinergi keyword enhanced at Sat Nov 12 11:37:51 UTC 2016
purpose:
The FIRM is the basis for floodplain management, mitigation, and insurance activities for the National Flood Insurance Program
(NFIP). Insurance applications include enforcement of the mandatory purchase requirement of the Flood Disaster Protection
Act, which "... requires the purchase of flood insurance by property owners who are being assisted by Federal programs or
by Federally supervised, regulated or insured agencies or institutions in the acquisition or improvement of land facilities"
(Section 2 (b) (4) of the Flood Disaster Protection Act of 1973). In addition to the identification of Special Flood Hazard
Areas (SFHAs), the risk zones shown on the FIRMs are the basis for the establishment of premium rates for flood coverage offered
through the NFIP. The NFHL data present the flood risk information depicted on the FIRM in a digital format suitable for use
in electronic mapping applications. The NFHL database is a subset of the information created for the FISand serves as a means
to archive a portion of the information collected during the FIS.
Resource language:
eng; USA
Resource progress code:
in work
Resource Maintenance Information
maintenance or update frequency:
unknown
Constraints on resource usage:
Legal Constraints
Access Constraints
otherRestrictions
use constraint:
otherRestrictions
Other constraints
Access Constraints: None. Use Constraints: Acknowledgement of FEMA would be appreciated in products derived from these data.
Spatial representation type code:
vector
Processing environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.3000
Resource extent
Geographic Extent
Geographic Bounding Box
westBoundLongitude
-108.298858040792
eastBoundLongitude
-103.052610053201
northBoundLatitude
36.2198750411121
southBoundLatitude
32.0002060095296
Temporal Extent
Represents effective DFIRMs and LOMRs available as of the publication date for the acquired State or Territory data set.
2009-01-16
point of contact
-
pointOfContact
organisation Name
Federal Emergency Management Agency
Contact information
Telephone
Voice 1-877-FEMA-MAP
Address
500 C Street, S.W., Washington, District of Columbia, 20472
Country USA
description The individual components of the National Flood Hazard Layer data are compiled in conjunction with the hardcopy FIRM and the
final FIS report. The specifics of the hydrologic and hydraulic analyses performed are detailed in the FIS reports available
for each community. The results of these studies are submitted in digital format to FEMA. These data and unrevised data from
effective FIRMs are compiled onto the base map used for DFIRM publication and checked for accuracy and compliance with FEMA
standards. As new DFIRM data sets are received the individual DFIRM layers are sewn into the nationwide layers of the NFHL.
LOMRs for the DFIRMs in the NFHL are cut directly into the NFHL data layers as they are being produced and finalized.
organisation Name
Federal Emergency Management Agency
Resource extent
Temporal Extent
Available effective DFIRMs and LOMRs issued against those DFIRMs.
2009-01-16
Completeness Commission
ConceptualConsistency
measure Description
When FEMA revises an FIS, adjacent studies are checked to ensure agreement between flood elevations at the boundaries. Likewise
flood elevations at the confluence of streams studied independently are checked to ensure agreement at the confluence. The
FIRM and the FIS are developed together and care is taken to ensure that the elevations and other features shown on the flood
profiles in the FIS agree with the information shown on the FIRM. However, the elevations as shown on the FIRM are rounded
whole-foot elevations. They must be shown so that a profile recreated from the elevations on the FIRM will match the FIS profiles
within one half of one foot.