Identification Information

Abstract 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 scale of 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.
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 FIS and serves as a means to archive a portion of the information collected during the FIS.

Time Period of Content

Single Date/Time

Calendar Date 2013-09-27

Currentness Reference Represents effective DFIRMs and LOMRs available as of the publication date for the acquired State or Territory data set.

Status

Progress In work
Maintenance and Update Frequency Monthly

Spatial Domain

Bounding Coordinates

West Bounding Coordinate -109.125
East Bounding Coordinate -103.0
North Bounding Coordinate 37.125
South Bounding Coordinate 31.75

Keywords

Theme

Thesaurus FEMA NFIP Topic Category
Keyword DFIRM
Keyword FIRM
Keyword FEMA Flood Hazard Zone
Keyword DFIRM Database
Keyword Special Flood Hazard Area
Keyword Digital Flood Insurance Rate Map
Keyword CBRS
Keyword Coastal Barrier Resources System
Keyword Riverine Flooding
Keyword Coastal Flooding
Keyword NFIP
Keyword Base Flood Elevation
Keyword SFHA
Keyword Flood Insurance Rate Map
Keyword Floodway

Theme

Thesaurus ISO 19115 Topic Categories
Keyword environment

Place

Thesaurus Country
Keyword U.S.

Place

Thesaurus State
Keyword New Mexcio

Access Constraints None

Use Constraints Acknowledgement of FEMA would be appreciated in products derived from these data.

Point of Contact

Contact Information

Contact Person Primary

Contact Person
Contact Organization

Contact Organization Primary

Contact Organization Federal Emergency Management Agency
Contact Person

Contact Position

Contact Address

Address Type mailing address
Address 500 C Street, S.W.
City Washington
State or Province District of Columbia
Postal Code 20472
Country USA

Contact Voice Telephone 1-877-FEMA-MAP

Contact Facsimile Telephone

Contact Electronic Mail Address fema-mscservice@dhs.gov

Hours of Service

Contact Instructions

Native Data Set Environment Microsoft Windows Vista Version 6.1 (Build 7601) Service Pack 1; ESRI ArcCatalog 9.3.1.3000

Cross Reference

Citation Information

Originator Federal Emergency Management Agency

Publication Date 2013-09-27

Publication Time

Title Unknown

Geospatial Data Presentation Form vector digital data

Publication Information

Publication Place Washington, DC
Publisher Federal Emergency Management Agency

Other Citation Details

Online Linkage http://www.msc.fema.gov

Data Quality Information

Attribute Accuracy Report

Report 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 consists of community based vector files and associated attributes produced in conjunction with the hard copy FEMA FIRM. The published effective FIRM and DFIRM maps are issued as the official designation of the Special Flood Hazard Areas (SFHAs). As such they are adopted by local communities and form the basis for administration of the National Flood Insurance Program (NFIP). For these purposes they are authoritative. Provisions exist in the regulations for public review, appeals and corrections of the flood risk information shown to better match real world conditions. As with any engineering analysis of this type, variation from the estimated flood heights and floodplain boundaries is possible. Details of FEMA's requirements for the FISs and flood mapping process that produces these data are available in the Guidelines and Specifications for Flood Hazard Mapping Partners. Attribute accuracy was tested by manual comparison of source graphics with hardcopy plots and a symbolized display on an interactive computer graphic system. Independent quality control testing of FEMA's DFIRM databases was also performed. To obtain more detailed information in areas where Base Flood Elevations (BFEs) and/or floodways have been determined, users are encouraged to consult the Flood Profiles and Floodway Data and/or Summary of Stillwater Elevations tables contained within the FIS report that accompanies the individual components of the DFIRM data. Users should be aware that BFEs shown in the S_BFE table represent rounded whole-foot elevations. These BFEs are intended for flood insurance rating purposes only and should not be used as the sole source of flood elevation information. Accordingly, flood elevation data presented in the FIS report must be used in conjunction with the FIRM for purposes of construction and/or floodplain management. The 1-percent-annual-chance water-surface elevations shown in the S_XS table match the regulatory elevations shown in the FIS report.

Quantitative Attribute Accuracy Assessment

Attribute Accuracy Value
Attribute Accuracy Explanation

Horizontal Positional Accuracy Report

Report The National Flood Hazard Layer data consists of community based vector files and associated attributes produced in conjunction with the hardcopy FEMA FIRM. The published effective FIRM and DFIRM maps are issued as the official designation of the SFHAs. As such they are adopted by local communities and form the basis for administration of the NFIP. For these purposes they are authoritative. Provisions exist in the regulations for public review, appeals and corrections of the flood risk information shown to better match real world conditions. As with any engineering analysis of this type, variation from the estimated flood heights and floodplain boundaries is possible. Details of FEMA's requirements for the FISs and flood mapping process that produces these data are available in the Guidelines and Specifications for Flood Hazard Mapping Partners. Horizontal accuracy was tested by manual comparison of source graphics with hardcopy plots and a symbolized display on an interactive computer graphic system. Independent quality control testing of the individual DFIRM data sets was also performed.

Quantitative Horizontal Positional Accuracy Assessment

Horizontal Positional Accuracy Value
Horizontal Positional Accuracy Explanation

Vertical Positional Accuracy Report

Report The National Flood Hazard Layer data consists of community based vector files and associated attributes produced in conjunction with the hardcopy FEMA FIRM. The published effective FIRM and DFIRM maps are issued as the official designation of the SFHAs. As such they are adopted by local communities and form the basis for administration of the NFIP. For these purposes they are authoritative. Provisions exist in the regulations for public review, appeals and corrections of the flood risk information shown to better match real world conditions. As with any engineering analysis of this type, variation from the estimated flood heights and floodplain boundaries is possible. Details of FEMA's requirements for the FISs and flood mapping process that produces these data are available in the Guidelines and Specifications for Flood Hazard Mapping Partners. Vertical accuracy was tested by manual comparison of source graphics with hardcopy plots and a symbolized display on an interactive computer graphic system. Independent quality control testing of the individual DFIRM data sets was also performed.

Quantitative Vertical Positional Accuracy Assessment

Vertical Positional Accuracy Value
Vertical Positional Accuracy Explanation

Logical Consistency Report 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.

Completeness Report Information contained in the National Flood Hazard Layer data reflects the content of the source materials. Features may have been eliminated or generalized on the source graphic, due to scale and legibility constraints. With new mapping, FEMA plans to maintain full detail in the spatial data it produces. However, older information is often transferred from existing maps where some generalization has taken place. Flood risk data are developed for communities participating in the NFIP for use in insurance rating and for floodplain management. Flood hazard areas are determined using statistical analyses of records of river flow, storm tides, and rainfall; information obtained through consultation with the communities; floodplain topographic surveys; and hydrological and hydraulic analysis. Both detailed and approximate analyses are employed. Generally, detailed analyses are used to generate flood risk data only for developed or developing areas of communities. For areas where little or no development is expected to occur, FEMA uses approximate analyses to generate flood risk data. Typically, only drainage areas that are greater than one square mile are studied. The National Flood Hazard Layer data reflects the most current information available when the distribution data set was created.

Lineage

Source Information

Source Citation

Citation Information

Originator Federal Emergency Management Agency

Publication Date 2013-09-27

Publication Time

Title National Flood Hazard Layer

Geospatial Data Presentation Form

Publication Information

Publication Place
Publisher

Other Citation Details

Source Scale Denominator

Type of Source Media digital tape media

Source Time Period of Content

Source Currentness Reference Available effective DFIRMs and LOMRs issued against those DFIRMs.

Source Citation Abbreviation NFHL

Source Contribution Spatial and attribute information, floodplain widths, BFEs, floodplain location.

Process Step

Process 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.
Process Date 2013-09-27
Process Time
Process Contact

Spatial Data Organization Information

Indirect Spatial Reference Method New Mexico

Direct Spatial Reference Method Vector

Point and Vector Object Information

SDTS Terms Description

SDTS Point and Vector Object Type G-polygon
Point and Vector Object Count 7651

Spatial Reference Information

Spatial Reference

Name North American Datum of 1983
Code EPSG:4269
URL http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:crs:EPSG::4269

Spatial Reference

Name Geodetic Reference System 80
Code EPSG:7019
URL http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:ellipsoid:EPSG::7019

Spatial Reference

Name Mixed
Code EDAC:Unknown
URL http://gstore.unm.edu/spref/EDAC-Unknown

Entity and Attribute Information

Detailed Description

Entity Type

Entity Type LabelS_FLD_HAZ_AR
Entity Type Definition Location and attributes for a tiling index for raster data used for the DFIRM
Entity Type Definition Source FEMA Guidelines and Specifications for Flood Hazard Mapping Partners, Appendix L: Guidance for Preparing Draft Digital Data and DFIRM Databases (available at http://www.fema.gov/fhm/dl_cgs.shtm)

Attribute

Attribute Label FID

Attribute Definition Internal feature number.

Attribute Definition Source ESRI

Attribute Domain Values

Unrepresentable Domain Sequential unique whole numbers that are automatically generated.

Attribute

Attribute Label Shape

Attribute Definition Feature geometry.

Attribute Definition Source ESRI

Attribute Domain Values

Unrepresentable Domain Coordinates defining the features.

Attribute

Attribute Label OBJECTID

Attribute Definition Unknown - contact originator for additional information

Attribute Definition Source Unknown - contact originator for additional information

Attribute Domain Values

Unrepresentable Domain Unknown - contact originator for additional information

Attribute

Attribute Label DFIRM_ID

Attribute Definition Identification number for the Digital Flood Insurance Rate Map