National Flood Hazard Layer (NFHL) for development of the Parcel Inventory dataset for the Housing Element Site Selection (HESS) Pre-Screening Tool. This 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. In addition to the identification of Special Flood Hazard Areas, the risk zones shown on the FIRMs are the basis for the establishment of premium rates for flood coverage offered through the National Flood Insurance Program. 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. ** This flood zone data should not be used for flood insurance purposes, but rather hazard mapping. FIRM data retrieved directly from the FEMA should be used for insurance programs. Source data, by county, was downloaded from https://msc.fema.gov/portal/advanceSearch.
This dataset has the following 24 columns:
| Column Name | API Column Name | Data Type | Description | Sample Values |
|---|---|---|---|---|
| dfirm_id | dfirm_id | text | Study Identifier. This is the Digital Flood Insurance Rate Map (DFIRM) identification value for the countywide Flood Risk Project, the values for this column are composed of the two-digit State Federal Information Processing Series (FIPS) code, the three-digit county FIPS code and the letter “C” (e.g., 48107C). Within each Flood Insurance Rate Map Database, the DFIRM_ID value will be identical. | 06013C 06085C 06001C 06097C 06095C view top 100 |
| version_id | version_id | text | Version Identifier. Identifies the product version and relates the feature to standards according to how it was created. | 1.1.1.0 2.3.2.0 2.3.3.2 2.3.2.1 2.1.3.0 view top 100 |
| fld_ar_id | fld_ar_id | text | Primary key for table lookup. Assigned by table creator. | 06001C_100 06001C_1001 06001C_1004 06001C_1006 06001C_1011 view top 100 |
| study_typ | study_typ | text | Study Type. This describes the type of Flood Risk Project performed for flood hazard identification. Column values are DIGITAL CONVERSION (Mapping products created by converting non-revised effective FIRM information to digital format), NP (Not populated), REDELINEATION (Mapping products created by redelineating floodplains using updated topographic data), SFHAs WITH HIGH FLOOD RISK (Shaded X - an area of moderate flood hazard that is determined to be outside the Special Flood Hazard Area between the limits of the base flood and the 0.2-percent-annual-chance (or 500-year) flood), and SFHAs WITH LOW FLOOD RISK (Unshaded X - an area of minimal flood hazard that is determined to be outside the Special Flood Hazard Area and higher than the elevation of the 0.2-percent-annual-chance (or 500-year) flood). | NP SFHAs WITH HIGH FLOOD RISK REDELINEATION SFHAs WITH LOW FLOOD RISK view top 100 |
| fld_zone | fld_zone | text | Flood Zone. This is a flood zone designation. These zones are used by FEMA to designate the SFHAs and for insurance rating purposes. Column values are A (Areas subject to inundation by the 1-percent-annual-chance flood event generally determined using approximate methodologies. Because detailed hydraulic analyses have not been performed, no Base Flood Elevations (BFEs) or flood depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply), A99 (Areas subject to inundation by the 1-percent-annual-chance flood event, but which will ultimately be protected upon completion of an under-construction Federal flood protection system. These are areas of special flood hazard where enough progress has been made on the construction of a protection system, such as dikes, dams, and levees, to consider it complete for insurance rating purposes. Zone A99 may only be used when the flood protection system has reached specified statutory progress toward completion. No Base Flood Elevations (BFEs) or depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply), AE (Areas subject to inundation by the 1-percent-annual-chance flood event determined by detailed methods. Base Flood Elevations (BFEs) are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply), AH (Areas subject to inundation by 1-percent-annual-chance shallow flooding (usually areas of ponding) where average depths are between one and three feet. Base Flood Elevations (BFEs) derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance purchase requirements and floodplain management standards apply), AO (Areas subject to inundation by 1-percent-annual-chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between one and three feet. Average flood depths derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance purchase requirements and floodplain management standards apply. Some Zone AO have been designated in areas with high flood velocities such as alluvial fans and washes. Communities are encouraged to adopt more restrictive rquirements for these areas), AREA NOT INCLUDED (An area that is located within a community or county that is not mapped on any published FIRM), D (The Zone D designation is used for areas where there are possible but undetermined flood hazards, as no analysis of flood hazards has been conducted. The designation of Zone D is also used when a community incorporates portions of another community’s area where no map has been prepared), OPEN WATER (Open water), V (Areas along coasts subject to inundation by the 1-percent-annual-chance flood event with additional hazards associated with storm-induced waves. Because detailed hydraulic analyses have not been performed, no Base Flood Elevations (BFEs) or flood depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply), VE (Areas subject to inundation by the 1-percent-annual-chance flood event with additional hazards due to storm-induced velocity wave action. Base Flood Elevations (BFEs) derived from detailed hydraulic analyses are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply), and X (Zone X is classified as Shaded or Unshaded. (1) Shaded Zone X: Areas of 0.2% annual chance flood hazards and areas of 1% annual chance flood hazards with average depths of less than 1 foot or with drainage areas less than 1 square mile. (2) Future Conditions: 1% Annual Chance Flood Hazard - Zone X: The flood insurance rate zone that corresponds to the 1% annual chance floodplains that are determined based on future-conditions hydrology. No base flood elevations or flood depths are shown within this zone. (3) Area with Reduced Flood Risk due to Levee: Areas where an accredited levee, dike, or other flood control structure has reduced the flood risk from the 1% annual chance flood. See Notes to Users for important information. (4) Area with Flood Risk due to Levee: Areas where a non-accredited levee, dike, or other flood control structure is shown as providing protection to less than the 1% annual chance flood. (5) Unshaded Zone X: Areas of minimal flood hazard). | AE A AO VE AH view top 100 |
| zone_subty | zone_subty | text | 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. NOTE: The symbol ‘%’ is a reserved symbol in most software packages, so the word ‘percent’ was abbreviated to ‘PCT’. Column values are 0.2 PCT ANNUAL CHANCE FLOOD HAZARD (500-year flood zone), 0.2 PCT ANNUAL CHANCE FLOOD HAZARD CONTAINED IN CHANNEL (500-year flood zone in channel), 1 PCT ANNUAL CHANCE FLOOD HAZARD CONTAINED IN CHANNEL (100-year flood zone in channel), 1 PCT ANNUAL CHANCE FLOOD HAZARD CONTAINED IN STRUCTURE (100-year flood zone in structure), 1 PCT DEPTH LESS THAN 1 FOOT (Shaded Zone X: 1% annual chance flood hazards with average depths of less than 1 foot. This zone is classified as being within the 500 year floodplain and not the 100 year floodplain because of the following: Flood zones AH and AO reference a base flood depth between 1 and 3 feet. This is in place of a Base Flood Elevation. An area that has a base flood depth below 1 foot is considered to be flood zone X, since the area affected by the 100 year flooding event would be too shallow or too small to identify on the Flood Insurance Rate Map. Please refer to the Shallow Flooding Analyses and Mapping technical document at https://www.fema.gov/media-library-data/1484865782763-4d150592d6eae9fdb5e2c2ab597928a6/Shallow_Flooding_Guidance_Nov_2016.pdf for more information on this classification), AREA OF MINIMAL FLOOD HAZARD (Unshaded Zone X: Areas of minimal flood hazard), AREA WITH REDUCED FLOOD RISK DUE TO LEVEE (Area with Reduced Flood Risk due to Levee: Areas where an accredited levee, dike, or other flood control structure has reduced the flood risk from the 1% annual chance flood (100-year flood zone)), FLOODWAY (A "Regulatory Floodway" means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height. Communities must regulate development in these floodways to ensure that there are no increases in upstream flood elevations. For streams and other watercourses where FEMA has provided Base Flood Elevations (BFEs), but no floodway has been designated, the community must review floodplain development on a case-by-case basis to ensure that increases in water surface elevations do not occur, or identify the need to adopt a floodway if adequate information is available), and FLOODWAY CONTAINED IN CHANNEL (An area where the floodway is contained within the channel banks and the channel is too narrow to show to scale. An arbitrary channel width of 3 meters is shown. BFEs are not shown in this area, although they may be reflected on the corresponding profile). | FLOODWAY 1 PCT ANNUAL CHANCE FLOOD HAZARD CONTAINED IN CHANNEL FLOODWAY CONTAINED IN CHANNEL 1 PCT ANNUAL CHANCE FLOOD HAZARD CONTAINED IN STRUCTURE view top 100 |
| sfha_tf | sfha_tf | text | 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. Column values are T (True/Yes - area is within a Special Flood Hazard Area) and F (False/No - area is not within a Special Flood Hazard Area). | T view top 100 |
| static_bfe | static_bfe | number | 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. | -9999.0 10.0 11.0 12.0 9.0 view top 100 |
| v_datum | v_datum | text | 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. | NAVD88 view top 100 |
| depth | depth | number | 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. | -9999.0 1.0 2.0 3.0 0.0 view top 100 |
| len_unit | len_unit | text | 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. Column values are either Feet (Measurement system used for Base Flood Elevations and/or depths is feet (US Feet)) or | Feet view top 100 |
| velocity | velocity | number | 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. | -9999.0 0.0 view top 100 |
| vel_unit | vel_unit | text | Velocity Unit. This is the unit of measurement for the velocity. This field is populated when the VELOCITY field is populated. *There are no values in this field* | view top 100 |
| ar_revert | ar_revert | text | Flood Control Restoration Zones – Zone AR Classification. If this area is 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. *There are no values in this field* | view top 100 |
| ar_subtrv | ar_subtrv | text | 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. NOTE: The symbol ‘%’ is a reserved symbol in most software packages, so the word ‘percent’ was abbreviated to ‘PCT.’ Acceptable values for this field must be one of the allowable subtypes for Zones AE, AO, AH, A or X. *There are no values in this field* | view top 100 |
| bfe_revert | bfe_revert | number | 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. | -9999.0 0.0 view top 100 |
| dep_revert | dep_revert | number | 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. | -9999.0 0.0 view top 100 |
| dual_zone | dual_zone | text | 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. *There are no values in this field* | view top 100 |
| source_cit | source_cit | text | Source Citation. Abbreviation used in the metadata file when describing the source information for the feature. | 06085C_FIRM1 06097C_FIRM1 06013C_STUDY9 06013C_STUDY29 06085C_FIRM12 view top 100 |
| st_area_sh | st_area_sh | number | Feature area in square meters. | 0.000158425036848 0.000344719937845 0.00166838003274 0.00318497496313 0.00594376982428 view top 100 |
| st_perimet | st_perimet | number | Feature perimeter length in meters. | 0.148304155693 0.285809821657 0.400171357864 0.729325992046 0.740051858701 view top 100 |
| Shape_Length | shape_length | number | Feature perimeter length in decimal degrees. | 0.000001389769150331493 0.0000026073703459674354 0.0000037400316269861555 0.000007438031510108239 0.000007462060860463327 view top 100 |
| Shape_Area | shape_area | number | Feature perimeter length in square decimal degrees. | 1.5977501958295038E-14 3.525149154798274E-14 1.7269047591507745E-13 3.242219848293278E-13 6.113163952351656E-13 view top 100 |
| geometry | geometry | multipolygon | Feature geometry. Coordinates defining the features. | view top 100 |