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 |
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GENERAL DESCRIPTION:
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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. |
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BFE_LN_ID |
Primary key for table lookup. Assigned by table creator. |
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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. |
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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. |
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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. |
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SOURCE_CIT |
Source Citation. Abbreviation used in the metadata file when describing the source information for the S_BFE table. |
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COUNTY |
The county name. |
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DESCRIPT |
Based on fields [ELEV] and [LEN_UNIT]. |
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SOURCEDATE |
The date the Source created the data. |
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FGDLAQDATE |
The date FGDL acquired the data from the Source. |
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AUTOID |
FGDL feature identification number. |
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SHAPE |
Feature geometry. |
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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. |
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 |
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 |
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 |
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 |
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