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FEMA

Summary

Contains information about the flood hazards within the Flood Risk Project area. These zones are used by FEMA to designate the Special Flood Hazard Area (SFHA) and for insurance rating purposes. These data are the regulatory flood zones designated by FEMA. Corresponds to the table S_Fld_Haz_ar within the FIRM database.

Description

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 located or to be located in identified areas having special flood hazards, " 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 FIRM Database presents the flood risk information depicted on the FIRM in a digital format suitable for use in electronic mapping applications. The FIRM Database serves to archive the information collected during the Flood Risk Project.

The National Flood Hazard Layer (NFHL) data incorporates all Flood Insurance Rate Map (FIRM) databases published by the Federal Emergency Management Agency (FEMA), and any Letters Of Map Revision (LOMRs) that have been issued against those databases since their publication date. It is updated on a monthly basis. The FIRM Database is the digital, geospatial version of the flood hazard information shown on the published paper FIRMs. The FIRM Database depicts flood risk information and supporting data used to develop the risk data. 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 FIRM Database is derived from Flood Insurance Studies (FISs), previously published 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 FEMA. The NFHL is available as State or US Territory data sets. Each State or Territory data set consists of all FIRM Databases and corresponding LOMRs available on the publication date of the data set. The specification for the horizontal control of FIRM Databases is consistent with those required for mapping at a scale of 1:12,000. This file is georeferenced to the Earth's surface using the Geographic Coordinate System (GCS) and North American Dataum of 1983 (NSRS-2007).

Last Update

11-15-2013

Attributes

Name Type Details Description
DFIRM_ID type: String
width: 6
precision: 0 Study Identifier. For a single jurisdiction Flood Risk Project, the value is composed of the two-digit State FIPS code and the four-digit FEMA CID code (e.g. 480001). For a countywide Flood Risk Project, the value is composed of the two-digit State FIPS code, the three-digit county FIPS code and the letter “C” (e.g. 48107C). Within each FIRM Database, the DFIRM_ID value will be identical.
VERSION_ID type: String
width: 11
precision: 0 Version Identifier. Identifies the product version and relates the feature to standards according to how it was created.
FLD_AR_ID type: String
width: 32
precision: 0 Primary key for table lookup. Assigned by table creator
STUDY_TYP type: String
width: 28
precision: 0 Study Type. This describes the type of Flood Risk Project performed for flood hazard identification. Acceptable values for this field are listed in the D_Study_Typ table.
ZONE_SUBTY type: String
width: 57
precision: 0 Flood Zone Subtype. This field captures additional information about the flood zones not related to insurance rating purposes. For example, Zone X could have “AREA WITH REDUCED FLOOD RISK DUE TO LEVEE” or “0.2 PCT ANNUAL CHANCE FLOOD HAZARD” as a subtype. Types of floodways are also stored in this field. Floodways are designated by FEMA and adopted by communities to provide an area that will remain free of development to moderate increases in flood heights due to encroachment on the floodplain. Normal floodways are specified as ‘FLOODWAY.’ Special cases will have a more specific term for the designation (such as COLORADO RIVER) and will appear as a note on the hardcopy FIRM. See the FIRM Panel Technical Reference for available floodway notes. Acceptable values for this field are listed in the D_Zone_Subtype table
STATIC_BFE type: Double
width: 8
precision: 38 Static Base Flood Elevation. This field will be populated for areas that have been determined to have a constant Base Flood Elevation (BFE) over a flood zone. The BFE value will be shown beneath the zone label. In this situation the same BFE applies to the entire polygon. This normally occurs in lakes or coastal zones.
V_DATUM type: String
width: 17
precision: 0 Vertical Datum. The vertical datum indicates the reference surface from which the flood elevations are measured. Normally this would be North American Vertical Datum of 1988 for new studies. This field is only populated if the STATIC_BFE field is populated. Acceptable values for this field are listed in the D_V_Datum table.
DEPTH type: Double
width: 8
precision: 38 Depth This is the depth for Zone AO areas. This value is shown beneath the zone label on the FIRM. This field is only populated if a depth is shown on the FIRM.
LEN_UNIT type: String
width: 16
precision: 0 Length Units. This unit indicates the measurement system used for the BFEs and/or depths. Normally this would be feet. This field is only populated if the STATIC_BFE or DEPTH field is populated. Acceptable values for this field are listed in the D_Length_Units table
VELOCITY type: Double
width: 8
precision: 38 Velocity. This is the velocity measurement of the flood flow in the area. Normally this is applicable to alluvial fan areas (certain Zone AO areas). This value is shown beneath the zone label on the FIRM. This field is only populated when a velocity is associated with the flood zone area
VEL_UNIT type: String
width: 20
precision: 0 Velocity Unit. This is the unit of measurement for the velocity. This field is populated when the VELOCITY field is populated. Acceptable values for this field are listed in the D_Velocity_Units table.
AR_REVERT type: String
width: 17
precision: 0 Flood Control Restoration Zones – Zone AR Classification. If this areais Zone AR in FLD_Zone field, this field would hold the zone that area would revert to if the AR zone were removed. This field is only populated if the corresponding area is Zone AR. Acceptable values for this field are listed in the D_Zone table, but should only include one of AE, AO, AH, A, and X domain values.
AR_SUBTRV type: String
width: 57
precision: 0 Flood Control Restoration Zones – Zone AR Classification Zone Subtype. If this area is Zone AR in FLD_Zone field, this field would hold the zone subtype that area would revert to if the AR zone were removed. This field is only populated if the corresponding area is Zone AR. Acceptable values for this field are listed in the D_Zone_Subtype_ table and must be one of the allowable subtypes for Zones AE, AO, AH, A or X
BFE_REVERT type: Double
width: 8
precision: 38 Flood Control Restoration Zones – BFE Revert. If zone is Zone AR in FLD_Zone field, this field would hold the static base flood elevation for the reverted zone. This field is populated when Zone equals AR and the reverted zone has a static BFE.
DEP_REVERT type: Double
width: 8
precision: 38 Flood Control Restoration Zones – Depth Revert. If zone is Zone AR in FLD_Zone field, this field would hold the flood depth for the reverted zone. This field is populated when Zone equals AR and the reverted zone has a depth assigned.
DUAL_ZONE type: String
width: 1
precision: 0 Flood Control Restoration Zones – Dual Zone Classification. If the flood hazard areas shown on the effective FIRM shall be designated as “dual” flood insurance rate zones (i.e., Zone AR/AE, Zone AR/AH, Zone AR/AO, Zone AR/A), this field will be coded as true. It should be false for any for AR Zones that revert to Shaded X. Acceptable values for this field are listed in the D_TrueFalse table.
FLOODZONE type: String
width: 20
precision: 0 Flood Zone. This is a flood zone designation. These zones are used by FEMA to designate the SFHAs and for insurance rating purposes. Acceptable values for this field are listed in the D_Zone table.
SFHA type: String
width: 3
precision: 0 Special Flood Hazard Area. If the area is within a SFHA this field would be true. This field will be true for any area coded as an A or V flood zone area. It should be false for any X or D flood areas. Acceptable values for this field are listed in the D_TrueFalse table.
SOURCE_CIT type: String
width: 21
precision: 0 Source Citation. Abbreviation used in the metadata file when describing the source information for the feature. The abbreviation must match a value in L_Source_Cit.

Name	Type Details	Description
DFIRM_ID	type: String width: 6 precision: 0	Study Identifier. For a single jurisdiction Flood Risk Project, the value is composed of the two-digit State FIPS code and the four-digit FEMA CID code (e.g. 480001). For a countywide Flood Risk Project, the value is composed of the two-digit State FIPS code, the three-digit county FIPS code and the letter “C” (e.g. 48107C). Within each FIRM Database, the DFIRM_ID value will be identical.
VERSION_ID	type: String width: 11 precision: 0	Version Identifier. Identifies the product version and relates the feature to standards according to how it was created.
FLD_AR_ID	type: String width: 32 precision: 0	Primary key for table lookup. Assigned by table creator
STUDY_TYP	type: String width: 28 precision: 0	Study Type. This describes the type of Flood Risk Project performed for flood hazard identification. Acceptable values for this field are listed in the D_Study_Typ table.
ZONE_SUBTY	type: String width: 57 precision: 0	Flood Zone Subtype. This field captures additional information about the flood zones not related to insurance rating purposes. For example, Zone X could have “AREA WITH REDUCED FLOOD RISK DUE TO LEVEE” or “0.2 PCT ANNUAL CHANCE FLOOD HAZARD” as a subtype. Types of floodways are also stored in this field. Floodways are designated by FEMA and adopted by communities to provide an area that will remain free of development to moderate increases in flood heights due to encroachment on the floodplain. Normal floodways are specified as ‘FLOODWAY.’ Special cases will have a more specific term for the designation (such as COLORADO RIVER) and will appear as a note on the hardcopy FIRM. See the FIRM Panel Technical Reference for available floodway notes. Acceptable values for this field are listed in the D_Zone_Subtype table
STATIC_BFE	type: Double width: 8 precision: 38	Static Base Flood Elevation. This field will be populated for areas that have been determined to have a constant Base Flood Elevation (BFE) over a flood zone. The BFE value will be shown beneath the zone label. In this situation the same BFE applies to the entire polygon. This normally occurs in lakes or coastal zones.
V_DATUM	type: String width: 17 precision: 0	Vertical Datum. The vertical datum indicates the reference surface from which the flood elevations are measured. Normally this would be North American Vertical Datum of 1988 for new studies. This field is only populated if the STATIC_BFE field is populated. Acceptable values for this field are listed in the D_V_Datum table.
DEPTH	type: Double width: 8 precision: 38	Depth This is the depth for Zone AO areas. This value is shown beneath the zone label on the FIRM. This field is only populated if a depth is shown on the FIRM.
LEN_UNIT	type: String width: 16 precision: 0	Length Units. This unit indicates the measurement system used for the BFEs and/or depths. Normally this would be feet. This field is only populated if the STATIC_BFE or DEPTH field is populated. Acceptable values for this field are listed in the D_Length_Units table
VELOCITY	type: Double width: 8 precision: 38	Velocity. This is the velocity measurement of the flood flow in the area. Normally this is applicable to alluvial fan areas (certain Zone AO areas). This value is shown beneath the zone label on the FIRM. This field is only populated when a velocity is associated with the flood zone area
VEL_UNIT	type: String width: 20 precision: 0	Velocity Unit. This is the unit of measurement for the velocity. This field is populated when the VELOCITY field is populated. Acceptable values for this field are listed in the D_Velocity_Units table.
AR_REVERT	type: String width: 17 precision: 0	Flood Control Restoration Zones – Zone AR Classification. If this areais Zone AR in FLD_Zone field, this field would hold the zone that area would revert to if the AR zone were removed. This field is only populated if the corresponding area is Zone AR. Acceptable values for this field are listed in the D_Zone table, but should only include one of AE, AO, AH, A, and X domain values.
AR_SUBTRV	type: String width: 57 precision: 0	Flood Control Restoration Zones – Zone AR Classification Zone Subtype. If this area is Zone AR in FLD_Zone field, this field would hold the zone subtype that area would revert to if the AR zone were removed. This field is only populated if the corresponding area is Zone AR. Acceptable values for this field are listed in the D_Zone_Subtype_ table and must be one of the allowable subtypes for Zones AE, AO, AH, A or X
BFE_REVERT	type: Double width: 8 precision: 38	Flood Control Restoration Zones – BFE Revert. If zone is Zone AR in FLD_Zone field, this field would hold the static base flood elevation for the reverted zone. This field is populated when Zone equals AR and the reverted zone has a static BFE.
DEP_REVERT	type: Double width: 8 precision: 38	Flood Control Restoration Zones – Depth Revert. If zone is Zone AR in FLD_Zone field, this field would hold the flood depth for the reverted zone. This field is populated when Zone equals AR and the reverted zone has a depth assigned.
DUAL_ZONE	type: String width: 1 precision: 0	Flood Control Restoration Zones – Dual Zone Classification. If the flood hazard areas shown on the effective FIRM shall be designated as “dual” flood insurance rate zones (i.e., Zone AR/AE, Zone AR/AH, Zone AR/AO, Zone AR/A), this field will be coded as true. It should be false for any for AR Zones that revert to Shaded X. Acceptable values for this field are listed in the D_TrueFalse table.
FLOODZONE	type: String width: 20 precision: 0	Flood Zone. This is a flood zone designation. These zones are used by FEMA to designate the SFHAs and for insurance rating purposes. Acceptable values for this field are listed in the D_Zone table.
SFHA	type: String width: 3 precision: 0	Special Flood Hazard Area. If the area is within a SFHA this field would be true. This field will be true for any area coded as an A or V flood zone area. It should be false for any X or D flood areas. Acceptable values for this field are listed in the D_TrueFalse table.
SOURCE_CIT	type: String width: 21 precision: 0	Source Citation. Abbreviation used in the metadata file when describing the source information for the feature. The abbreviation must match a value in L_Source_Cit.

Coordinate System

NAD 1983 StatePlane Massachusetts Mainland FIPS 2001 Feet

Credits

FEMA

Use Limitations

The hardcopy FIRM and FIRM Database and the accompanying FIS are the official designation of SFHAs and Base Flood Elevations (BFEs) for the NFIP. For the purposes of the NFIP, changes to the flood risk information published by FEMA may only be performed by FEMA and through the mechanisms established in the NFIP regulations (44 CFR Parts 59-78). These digital data are produced in conjunction with the hardcopy FIRMs and generally match the hardcopy map exactly. Acknowledgement of FEMA would be appreciated in products derived from these data.

Legal Constraints

There are no legal constraints for this item.

Data Dictionary

FEMA Flood Zones