DIGITAL FLOOD INSURANCE RATE MAP DATABASE, Edgefield County, SC

Resource lineage description

source

source description  Source Contribution: Spatial and attribute information for revised FIRM panels, BFEs, floodplain widths, and floodplain location.Source Type Paper

source citation

Title DIGITAL FLOOD INSURANCE RATE MAP DATABASE, Edgefield COUNTY AND INCORPORATED AREAS

publication  Date   2011-03-03

cited responsible party - originator

organisation Name  Federal Emergency Management Agency

source

source description  Source Contribution: Spatial and attribute information for county, and corporate boundary.Source Type online

source citation

Title Base map for Edgefield County, SC

publication  Date   2008-01-01

cited responsible party - originator

organisation Name  South Carolina Department of Natural Resources

source

source description  Source Contribution: Spatial and attribute information for hydrographic featuresSource Type online

source citation

Title Base map for Edgefield County, SC

publication  Date   2008-11-25

cited responsible party - originator

organisation Name  U.S. Geologic Survey, National Hydrography Dataset (NHD)

source

source description  Source Contribution: Geodetic Control data, bench marksSource Type online

source citation

Title Base map for Edgefield County, SC

publication  Date   2004-01-01

cited responsible party - originator

organisation Name  National Geodetic Survey (NGS)

source

source description  Source Contribution: Spatial and attribute information for airports, railroads, and road centerlines.Source Type online

source citation

Title Base map for Edgefield County, SC

publication  Date   2008-11-14

cited responsible party - originator

organisation Name  University of South Carolina Campus GIS Support

source

source description  Source Contribution: Source and attribute information for the Profile Base Lines, dams, and cross sections.Source Type paper

source citation

Title Flood Insurance Rate Map, EDGEFIELD COUNTY, SOUTH CAROLINA, USA and Incorporated areas.

publication  Date   2008-11-25

cited responsible party - originator

organisation Name  Federal Emergency Management Agency

AbsoluteExternalPositionalAccuracy

name Of Measure Horizontal Positional Accuracy Report

evaluation Method Description  The DFIRM Database consists of community based 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.

AbsoluteExternalPositionalAccuracy

name Of Measure Vertical Positional Accuracy Report

evaluation Method Description  The DFIRM Database consists of community based 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.

Completeness Commission

evaluation Method Description  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.

Completeness Omission

evaluation Method Description  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.

ConceptualConsistency

measure Description  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.