#  National Flood Hazard Layer 

### Available map layers (32)

Water Areas (0)

Location and attributes for hydrography features shown on FIRM as areas. The S_Wtr_Ar table contains information about surface water area features. A spatial file with location information also corresponds with this data table. The spatial elements representing surface water area features are polygons. Normally lakes, ponds and other wide bodies of water will be represented as polygons. The main purpose of the S_Wtr_Ar table is to provide a cartographic depiction of the areal surface water features for visual interpretation of the mapping data. As a result, the method for structuring surface water features as polygons is very flexible. This information is used in the Transect Locator Map and the FIRM Panel Index in the FIS report, as well as the FIRM panels. 

Subbasins (1)

Location and attributes for subbasins in the hydrologic analysis. The S_Subbasins table contains data specific to each subbasin in the hydrologic analysis, including the relationship of the subbasin to the hydrologic network. The subbasin may be specific to a detailed hydrologic model. It may also correspond to the drainage area used in a regression analysis, or to the drainage area for a stream gage. S_Subbasins is intended to store HUC8 information related to the hydrologic model. This information is used in the Basin Characteristics tables in the FIS report, as well as for the FIRM Panel Index Map. The spatial elements representing the subbasins are polygons. In some cases the extent of these polygons may overlap, for example, cumulative subbasin areas for a regression analysis. 

Alluvial Fans (2)

Location and attributes of alluvial fan studies. Only the 1-percent-annual-chance flood is mapped for alluvial fans. The alluvial fan could be mapped as: Zone AO areas with depths and velocities; Zone AO areas with just depths; or Zone A, AE, or X. This information is needed for the Summary of Alluvial Fan Analyses and Results of Alluvial Fan Analyses tables in the FIS report. 

Submittal Information (3)

Location of areas updated in this flood risk project along with attributes associated with each submittal. The S_Submittal_Info layer contains essential information about the flood risk project such as the FEMA case number and utilized engineering models. The spatial entities representing the flood risk project areas are polygons corresponding to the area to be revised by this case / the area covered by the FIRM being revised / the area where new hydraulic analyses are to be performed and/or the watershed boundaries of the catchments analyzed. These can be one or multiple irregular polygons that capture the extent of the flood risk project area(s). This information is used in the following tables in the FIS report: Summary of Contracted Studies Included in this FIS report, Summary of Hydrologic and Hydraulic Analyses, and Summary of Topographic Elevation Data Used in Mapping. 

Flood Hazard Zones (4)

Labels for flood zones. 

Flood Hazard Boundaries (5)

The S_Fld_Haz_Ln table contains information about the flood zone boundary features for the flood risk project area. Three types of flood hazard lines exist. These are: SFHA / FLOOD ZONE BOUNDARY, LIMIT LINES, and OTHER BOUNDARY. All lines that are associated with flood hazard zone boundaries are coded in the LN_TYP field as SFHA / FLOOD ZONE BOUNDARY, with the exception of LIMIT LINES. OTHER BOUNDARY line types include lines that indicate different source citations, apparent limits, or the end of spatial extents. OTHER BOUNDARY lines are not shown on the FIRM. 

Hydrologic Reaches (6)

Location of hydrologic reach between nodes. The hydrologic reach represents the connectivity between the subbasins and the flow direction between nodes in the hydrologic model. 

Primary Frontal Dunes (7)

Location and attributes for the primary frontal dune features for the coastal flood risk project area. TThe S_PFD_Ln spatial file contains information about the PFD features for the coastal flood risk project area. PFDs are not shown on the FIRM but are used in the coastal floodplain analysis. The spatial entities representing the PFDs are lines that represent the landward dune heel or where the gradient changes from steep to gentle. 

General Structures (8)

This table includes levees, floodwalls, or dikes that have been designed for flood control, including those portions that are closure structures, whether or not they have been demonstrated to meet the NFIP requirements in 44 CFR 65.10. This information is shown in the Levees table in the FIS report and on the FIRM panels. The S_Levee table contains information about levees shown on the FIRMs that are accredited and known to be protecting against the 1-percent-annual-chance flood, as well as levees that are provisionally accredited, de-accredited, and never accredited. The purpose of this table is to document the accreditation status of levees, as well as associated information necessary to be shown on the FIRM and for the population of FIS report text related to levee structures. The spatial entities representing levees are lines, drawn at the centerline of levees, floodwalls, and levee closure structures. 

Levees (9)

This table includes levees, floodwalls, or dikes that have been designed for flood control, including those portions that are closure structures, whether or not they have been demonstrated to meet the NFIP requirements in 44 CFR 65.10. This information is shown in the Levees table in the FIS report and on the FIRM panels. The S_Levee table contains information about levees shown on the FIRMs that are accredited and known to be protecting against the 1-percent-annual-chance flood, as well as levees that are provisionally accredited, de-accredited, and never accredited. The purpose of this table is to document the accreditation status of levees, as well as associated information necessary to be shown on the FIRM and for the population of FIS report text related to levee structures. The spatial entities representing levees are lines, drawn at the centerline of levees, floodwalls, and levee closure structures. 

Political Jurisdictions (10)

Authoritative CBRS boundary locations are shown on maps administered by the U.S. Fish and Wildlife Service. Normally, these areas are already shown on existing FIRMs for the area. CBRS areas have restrictions on Federal funding (including flood insurance coverage) after specified dates for new or substantially improved structures. This information is needed for the Coastal Barrier Resources System Information table in the FIS report and for the FIRM panels. 

Water Lines (11)

Location and attributes for hydrography features shown on FIRM as lines. The S_Wtr_Ln table contains information about surface water linear features. The spatial elements representing surface water line features are lines. Normally stream centerlines will be represented as line features. However, the main purpose of the S_Wtr_Ar table and the S_Wtr_Ln table is to provide a cartographic depiction of the surface water features for visual interpretation of the mapping data. As a result, the method for structuring surface water features as lines or polygons is very flexible. Lake shorelines and stream channel banks used to show lakes and wide rivers may be represented as polygons. However, they may be represented as lines based on the structure of the data received and the mapping partner’s discretion. Surface water features may appear in either the S_Wtr_Ar table or the S_Wtr_Ln table or both. The hydrologic structure of the modeled stream network will be represented by the S_Profil_Basln layer. This information is used in the Transect Locator Map and the FIRM Panel Index in the FIS report, as well as the FIRM panels. 

Limit of Moderate Wave Action (12)

The S_LiMWA layer is used when a Limit of Moderate Wave Action (LiMWA, previously described as a Coastal Zone A boundary line) is delineated within the coastal floodplain. The spatial entities representing the LiMWA are lines. The line represents the limit of 1.5-foot or greater waves in a Coastal AE Zone. 

Transect Baselines (13)

The S_Tsct_Basln spatial file contains information about the transect baseline used in the coastal flood hazard model. Typically, the S_Tsct_Basln represents the 0.0-foot elevation contour, the starting point for the transect, and the measuring point for the coastal mapping. The spatial elements representing the transect baselines are lines. When a coastal transect baseline and water lines are available for the same study reach, only the transect baseline shall be shown on the FIRM in order to eliminate overlaps. This information is used in the following tables in the FIS report: Transect Locator Map, as well as in the Flooding Sources Included this FIS Report, Summary of Coastal Analyses, Summary of Topographic Elevation Data Used in Mapping, and Coastal Transect Parameters. 

Profile Baselines (14)

The profile baseline shows the path of flood flows on the FIRM and is an accurate representation of the distance between cross sections, structures, nodes, or grids in the hydraulic model. The profile baseline is used for replicating the stationing and water-surface elevations found in the FIS report profiles, but in GIS format. This information is used in the following tables within the FIS report: Flooding Sources Included in this FIS report, Principal Flood Problems, Summary of Hydrologic and Hydraulic Analyses, Summary of Topographic Elevation Data Used in Mapping, the Stream-by_Stream Vertical Datum Conversion, and Summary of Contracted Studies Included in this FIS Report. 

Base Flood Elevations (15)

Base Flood Elevations for the 1% annual chance flood. 

Coastal Transects (16)

The S_Cst_Tsct_Ln table contains information about the Coastal Transect Lines within the flood risk project area, if applicable. The transect lines indicate the location that was used to provide representative topographic information for the coastal flood models used. Hydraulic analyses of coastal flood effects are executed along transects, which are cross sections taken perpendicular to the shoreline, representing a segment of coast with similar characteristics. Transect elevations are interpolated to delineate the coastal flood zones. The spatial elements representing coastal transects are lines that generally extend from offshore all the way across the coastal floodplain. Transects can also extend seaward when wave runup modeling is used to determine coastal flood hazards. This information is needed for the Transect Locator Map table and Coastal Transect Parameters table in the FIS report. 

Cross-Sections (17)

Normally, any FIRM that has associated flood profiles has cross sections. The S_XS table contains information about cross section lines. These lines usually represent the locations of channel surveys performed for input into the hydraulic model used to calculate flood elevations. Sometimes cross sections are interpolated between surveyed cross sections using high accuracy elevation data. Depending on the zone designation (Zone AE, Zone A, etc.), these locations may be shown on Flood Profiles in the FIS report and can be used to cross reference the Flood Profiles to the planimetric depiction of the flood hazards. This information is used in the Floodway Data Tables in the FIS report, as well as on the FIRM panels. 

Station Start Points (18)

Location and attributes for starting points for stream distance measurements. This table is used to populate the Floodway Data Tables and Flood Profiles, as well as the Flood Hazard and Non-Encroachment Data for Selected Streams table in the FIS report. The S_Stn_Start table contains information about station starting locations. These locations indicate the reference point that was used as the origin for distance measurements along streams and rivers. 

High Water Marks (19)

Location of high water marks. S_HWM table contains information about high water marks for the flood risk project area. This table is used for the Historic Flooding Elevations table in the FIS report, if this information is available. 

Nodes (20)

Location and attributes of points used to define the topology of the hydrologic network. The S_Nodes layer is used for hydrologic analyses where nodes were defined as part of the analysis. The contributing drainage area and the discharges for all frequencies required for the flood risk project (e.g. the 10-percent, 2-percent, 1-percent, and 0.2-percent-annual-chance floods) represent the discharges based on the cumulative upstream drainage area. The points or nodes usually lie on the profile baseline, which reside in S_Profil_Basln, or the hydro reach line which resides in S_Hydro_Reach. Nodes can represent sub basin outlets, junctions, reservoirs, structures, or diversions. Note that nodes are required at all flow change locations. This information is used in the following tables in the FIS report: Summary of Discharges, Summary of Summary of Non-Coastal Stillwater Elevations, and Flood Hazard and Non-Encroachment Data for Selected Streams. For hydraulic models that use nodes, such as SWMM or ICPR, the nodes can be used to represent structures or hydraulic elements. In these cases, the nodes and the profile baseline layer are used to represent the hydraulic connectivity of the network. Nodes can also represent more detailed inventory, such as manholes or curb inlets. 

Gages (21)

Information about gage locations used in this flood risk project. S_Gage table contains information about riverine gages for the flood risk project area. Coastal gages are stored in S_Cst_Gage. The spatial location of these gages may be some distance from areas from which flood hazards were determined. This information is needed for the Stream Gage Information Used to Determine Discharges table in the FIS report. 

Coastal Gages (22)

The S_Cst_Gage layer is used when gage information (from tide, wind, or buoy stations) is used in the determination or to support flood height calculations. Specifically, this table is used in the following situations: when tide gage information is used to support the calibration and validation of hydrodynamic models; when tide gage information is used in the determination of flood elevations by statistical analyses of annual extrema; when wave buoy data provides information regarding the wave climate in the flood risk project area; when wave buoy data has been used in the estimation of offshore wave conditions; for calibration and validation of a numerical wave model; and when data from wind stations has been used for water level hindcasts or wave estimation. This information is needed for the Tide Gage Analysis Specifics table in the FIS report. 

Datum Conversion Points (23)

Information regarding the location of points used to determine the datum conversion factor performed as part of this flood risk project. The S_Datum_Conv_Pt table is required when a vertical datum conversion was performed as part of the flood risk project. The spatial elements representing this layer are points. This information is used in the FIS report Datum Conversion Locations and Values table. 

River Mile Markers (24)

The S_Riv_Mrk table contains information about the river marks shown on the FIRM if applicable. A spatial file with location information also corresponds with this data table. The spatial entities representing the river marks are points. The points are generally located along the centerline of the river at regular intervals, or as indicated by the data source. 

Topographic Low Confidence Areas (25)

Location of topographic low confidence areas. This table is used for tracking areas of low confidence in topographic data, whether it be LiDAR, photogrammetry or IFSAR, as a required in the Data Capture Standards Technical Reference. The spatial entities representing topographic low confidence areas are polygons. The spatial information contains the bounding polygon for each topographic low confidence area, matching the full extents of the corresponding S_Submittal_Info terrain submittal record. 

PLSS (26)

The S_PLSS_Ar table contains information about the PLSS areas that are associated within the flood risk project area. These include the attributes for the range, township, and section areas. The spatial elements representing the PLSS areas are polygons. Generally, there is one polygon per section. 

Base Index (27)

Location and attributes of the raster base map files used for the FIRM. The S_Base_Index table contains information about the raster data used as a base map for the flood risk project area. The spatial elements representing raster base map tile index features are rectangular polygons. 

FIRM Panels (28)

The S_FIRM_Pan table contains information about the FIRM panel area. A spatial file with location information also corresponds with this data table. The spatial entities representing FIRM panels are polygons. The polygon for the FIRM panel corresponds to the panel neatlines. Panel boundaries are generally derived from USGS DOQQ boundaries. As a result, the panels are generally rectangular. In situations where a portion of a panel lies outside the jurisdiction being mapped, the user must refer to the S_Pol_Ar table to determine the portion of the panel area where the FIRM Database shows the effective flood hazard data for the mapped jurisdiction. This information is needed for the FIRM Panel Index and the following tables in the FIS report: Listing of NFIP Jurisdictions, Levees, Incorporated Letters of Map Change, and Coastal Barrier Resources System Information. The spatial entities representing FIRM panels are polygons. The polygon for the FIRM panel corresponds to the panel neatlines. Panel boundaries are generally derived from USGS DOQQ boundaries. As a result, the panels are generally rectangular. FIRM panels must not overlap or have gaps within a study. In situations where a portion of a panel lies outside the jurisdiction being mapped, the user must refer to the S_Pol_Ar table to determine the portion of the panel area where the FIRM Database shows the effective flood hazard data for the mapped jurisdiction. This information is needed for the FIRM Panel Index and the following tables in the FIS report: Listing of NFIP Jurisdictions, Levees, Incorporated Letters of Map Change, and Coastal Barrier Resources System Information. 

LOMAs (29)

The LOMA point layer indicates coordinates for Letters of Map Amendment, which can affect flood zone determination without a map change. Please be aware that LOMA point layer is provided ‘as is’ and that there are several issues that must be considered before using this information. The first is its positional accuracy. Where the point is shown on the map may, or may not, be totally accurate as there are a variety of methods that can be used to translate a mailing address into a geographic coordinate (geocoding). The second is the completeness of the dataset. This point layer only includes LOMAs that have a coordinate associated with them. There are a number of LOMAs that have been processed by FEMA which do not have any type of a coordinate associated with them and those LOMAs are not included within this data. The contents of the LOMA shapefile are derived from user input in eLOMA(within the MIP) as well as SOMA(also within the MIP), which is converted by the FME model into the shapefile. This process runs on a nightly basis automatically during the week. In addition, there is an https location where the public can download the LOMA Point shapefile and the metadata upon request from MIP help. 

LOMRs (30)

The S_LOMR feature class should contain at least one record for each Letter of Map Revision incorporated into the NFHL. Multipart polygons are not allowed. The spatial entities representing LOMRs are polygons. The spatial information contains the bounding polygon for each LOMR area, broken on panel boundaries. 

NFHL Availability (31)

Indicates availability of NFHL data by jurisdiction.