FLORIDA GEOGRAPHIC DATA LIBRARY DOCUMENTATION
VERSION 2007

TITLE: BASE FLOOD ELEVATION (BFE) LINES OF THE DIGITAL FLOOD INSURANCE RATE MAP (DFIRM) - APRIL 2008

Geodataset Name:       DFIRM_BFE_APR08
Geodataset Type:       SHAPEFILE
Geodataset Feature:    Polyline
Feature Count:         6682
GENERAL DESCRIPTION:
This dataset contains information about the Base Flood Elevations (BFE) within a study area. BFE lines indicate the rounded whole-foot water surface elevation of the 1-percent-annual-chance flood. The spatial elements representing BFE features are lines extending from Special Flood Hazard Area (SFHA) boundary to SFHA boundary. The BFE lines will have no visible gaps or overshoots between the SFHA boundary and the end of the BFE line at the publication scale of the DFIRM. However, the ends of the BFE lines are not necessarily snapped precisely to the SFHA boundary. Each BFE is represented by a single line. The Base Flood Elevation (BFE) information is required for any digital data where BFE lines will be shown on the corresponding Flood Insurance Rate Map (FIRM). Normally if there are any riverine AE zones, BFE lines are required. While BFE lines are depicted as wavy lines on the hardcopy FIRM, they should be primarily straight lines in the spatial data, although they may bend consistent with procedures described in Volume 1 of these Guidelines. The Digital Flood Insurance Rate Map (DFIRM) 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 (100 year), the 0.2-percent-annual-chance flood event (500 year), and areas of minimal flood risk. The DFIRM Database is 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 FEMA. This dataset is an update to the DFIRM_BFE_DEC07.shp layer.
DATA SOURCE(S):                    Federal Emergency Management Agency
SCALE OF ORIGINAL SOURCE MAPS:     12000
DATE OF AUTOMATION OF SOURCE:      20070928
GEODATASET EXTENT:                 Alachua County, Baker County, Bay County, Charlotte County, 
Dixie County, Escambia County, Flagler County, Gilchrist County, Gulf County, Lafayette County, 
Lake County, Leon County, Okaloosa County, Osceola County, Pinellas County, 
Santa Rosa County, Seminole County, St. Johns County, Suwannee County, Volusia County.

FEATURE ATTRIBUTE TABLES:

Datafile Name: DFIRM_BFE_APR08.DBF
ITEM NAME WIDTH TYPE N. DECIMAL DEGREES
OBJECTID
4 OID ---
BFE_LN_ID
11 String ---
ELEV
15 Number 2
LEN_UNIT
20 String ---
V_DATUM
6 String ---
SOURCE_CIT
11 String ---
COUNTY
20 String ---
DESCRIPT
30 String ---
SOURCEDATE
8 Date ---
FGDLAQDATE
8 Date ---
AUTOID
6 Number ---
SHAPE
4 Geometry ---
SHAPE.LEN
0 Double ---

FEATURE ATTRIBUTE TABLES CODES AND VALUES:

Item
Item Description
OBJECTID Internal feature number.

BFE_LN_ID Primary key for table lookup. Assigned by table creator.

ELEV BFE. The rounded, whole-foot elevation of the 1-percent-annual-chance flood. This is the value of the BFE that is printed next to the BFE line on the FIRM.

LEN_UNIT BFE Units. This unit indicates the measurement system used for the BFEs. Normally this would be feet. Acceptable values for this field are listed in the D_Length_Units table.

V_DATUM 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. Acceptable values for this field are listed in the D_V_Datum table.

SOURCE_CIT Source Citation. Abbreviation used in the metadata file when describing the source information for the S_BFE table.

COUNTY The county name.

DESCRIPT Based on fields [ELEV] and [LEN_UNIT].

SOURCEDATE The date the Source created the data.

FGDLAQDATE The date FGDL acquired the data from the Source.

AUTOID FGDL feature identification number.

SHAPE Feature geometry.

SHAPE.LEN Length in meters

The DFIRM Database is made up of several data themes containing both spatial and attribute information.
These data together represent the current flood risk for the subject area as identified by FEMA. The
attribute tables include SFHA locations, flood zone designations, BFEs, political entities, cross-section
locations, FIRM panel information, and other data related to the NFIP.
USER NOTES:
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.
Data contained in the DFIRM Database files reflect 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.
GeoPlan relied on the integrity of the attribute information within
the original data.
**  The following FEMA DFIRM information is from the frm_gsalb.pdf  **

Table: S_BFE
The Base Flood Elevation (BFE) table is required for any digital data where BFE 
lines will be shown on the corresponding Flood Insurance Rate Map (FIRM). 
Normally if there are any riverine AE zones, BFE lines are required.
The S_BFE table contains information about the BFEs within a study area. A 
spatial file with locational information also corresponds with this data table. BFE 
lines indicate the rounded whole-foot water surface elevation of the 
1-percent-annual-chance flood.
The spatial elements representing BFE features are lines extending from Special 
Flood Hazard Area (SFHA) boundary to SFHA boundary. The BFE lines will have 
no visible gaps or overshoots between the SFHA boundary and the end of the 
BFE line at the publication scale of the DFIRM. However, the ends of the BFE 
lines are not necessarily snapped precisely to the SFHA boundary. Each BFE is 
represented by a single line. While BFE lines are depicted as wavy lines on the 
hardcopy FIRM, they should be primarily straight lines in the spatial data, although 
they may bend consistent with procedures described in Volume 1 of these 
Guidelines.

Table: D_Length_Units
LEN_LID            LEN_UNIT 
1000               CENTIMETERS 
1010               FEET 
1020               INCHES 
1030               KILOMETERS 
1040               METERS 
1050               MILES 
1060               MILLIMETERS

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 DFIRM Database presents the flood risk information depicted on the FIRM in a digital format suitable
for use in electronic mapping applications. The DFIRM database is a subset of the Digital FIS database that
serves to archive the information collected during the FIS.

The DFIRM Database consists of countywide vector files and associated attributes produced in conjunction
with the hardcopy FEMA FIRM. The published effective FIRM and DFIRM 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 FEMA's DFIRM database was also performed.

The DFIRM Database consists of countywide 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 FEMA's DFIRM database was also performed.

THE DATA INCLUDED IN FGDL ARE 'AS IS' AND SHOULD NOT BE CONSTRUED
AS LEGALLY BINDING. THE UNIVERSITY OF FLORIDA GEOPLAN CENTER SHALL
NOT BE LIABLE FOR ANY DAMAGES SUFFERED AS A RESULT OF USING,
MODIFYING, CONTRIBUTING OR DISTRIBUTING THE MATERIALS.

A note about data scale: 

Scale is an important factor in data usage.  Certain scale datasets
are not suitable for some project, analysis, or modeling purposes.
Please be sure you are using the best available data. 

1:24000 scale datasets are recommended for projects that are at the
county level.
1:24000 data should NOT be used for high accuracy base mapping such
as property parcel boundaries.
1:100000 scale datasets are recommended for projects that are at the
multi-county or regional level.
1:125000 scale datasets are recommended for projects that are at the
regional or state level or larger.

Vector datasets with no defined scale or accuracy should be
considered suspect. Make sure you are familiar with your data
before using it for projects or analysis. Every effort has been
made to supply the user with data documentation. For additional
information, see the References section and the Data Source Contact
section of this documentation. For more information regarding
scale and accuracy, see our webpage at:
http://geoplan.ufl.edu/education.html

REFERENCES:
FEMA Map Service Center
http://msc.fema.gov

** What are you looking for?
**** DFIRM Databases

Guidelines and Specifications for Flood Hazard Mapping Partners
http://www.fema.gov/library/viewRecord.do?id=2206

** Appendix L: Guidance for Preparing Draft Digital Data and DFIRM Database
** Appendix L: Part 1
** Appendix L: Part 2

DATA LINEAGE SUMMARY:
The DFIRM Database is 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 report. 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.
Process Date: 20060616

GeoPlan Center ordered the DFIRM database for the 20 available Florida Counties on 20071210. Data ordered contained both Unincorporated and Incorporated Areas. http://msc.fema.gov The data arrived on DVD for the following 20-counties; Alachua County Bay County Charlotte County Dixie County Escambia County Flagler County Gilchrist County Gulf County Lafayette County Lake County Leon County Monroe County - (NOTE: No BFE Data Available) Okaloosa County Osceola County Pinellas County Santa Rosa County Seminole County St. Johns County Suwannee County Volusia County The countywide Digital Flood Insurance Rate Map (DFIRM) Base Flood Elevations (BFE) Databases were originally called: S_BFE.shp The data was reprojected from various UTM projections to the FGDL Albers HPGN NAD83 projection. GeoPlan then added the following fields. COUNTY DESCRIPT SOURCEDATE FGDLAQDATE AUTOID The final process step involved the merging of the 19 counties to create one partial coverage statewide layer. Process Date: 20071210
Data imported to ArcSDE and exported as a shapefile. Process Date: 20080125
GeoPlan Center ordered the DFIRM database for Baker County Florida on 20080411. The data arrived on DVD and the order contained both Unincorporated and Incorporated Areas. http://msc.fema.gov The countywide Digital Flood Insurance Rate Map (DFIRM) Base Flood Elevations (BFE) Database was originally called: S_BFE.shp The data was reprojected from NAD_1983_StatePlane_Florida_North_FIPS_0903_Feet to the FGDL Albers HPGN NAD83 projection. GeoPlan then added the following fields. COUNTY DESCRIPT SOURCEDATE FGDLAQDATE AUTOID The final process step involved the merging of the Baker County information with the existing SDE layer DFIRM_BFE_DEC07, creating a partial coverage statewide layer consisting of 20 counties. Process Date: 20080425
Data imported to ArcSDE and exported as a shapefile. Process Date: 20080521
MAP PROJECTION PARAMETERS:

Projection                          ALBERS
Datum                               HPGN
Units                               METERS
Spheroid                            GRS1980
1st Standard Parallel               24  0  0.000
2nd Standard Parallel               31 30  0.000
Central Meridian                   -84 00  0.000
Latitude of Projection's Origin     24  0  0.000
False Easting (meters)              400000.00000
False Northing (meters)             0.00000

DATA SOURCE CONTACT (S):

Name:
Abbr. Name:
Address:


Phone:

Web site:
E-mail:
Contact Person:
         Phone:
        E-mail:
Federal Emergency Management Agency
FEMA
500 C Street, S.W.
Washington, District of Columbia
20472
1-800-358-9616

www.msc.fema.gov www.msc.fema.gov

FGDL CONTACT:
Name:                   FLORIDA GEOGRAPHIC DATA LIBRARY
Abbr. Name:             FGDL
Address:                Florida Geographic Data Library
                        431 Architecture Building
                        PO Box 115706
                        Gainesville, FL  32611-5706
Web site:               http://www.fgdl.org

Contact FGDL: 

      Technical Support:	        http://www.fgdl.org/fgdlfeed.html
      FGDL Frequently Asked Questions:  http://www.fgdl.org/fgdlfaq.html
      FGDL Mailing Lists:		http://www.fgdl.org/fgdl-l.html
      For FGDL Software:                http://www.fgdl.org/software.html