DIGITAL FLOOD INSURANCE RATE MAP DATABASE, LAKE COUNTY, TENNESSEE AND INCORPORATED AREAS

Resource lineage description

source

source description  Source Contribution: Spatial and attribute information, floodplain widths, BFEs, floodplain location, general structures, FIRM Panel Neatlines, cross sectionsSource Type paper

source citation

Title Flood Insurance Study, LAKE County, Tennessee and Incorporated Areas

publication  Date   2010-06-04

other Citation Details  The sources of authority for this Flood Insurance Study are the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. This FIS was prepared to include the incorporated communities within LAKE County in a countywide format. The authority and acknowledgements for LAKE County, Tennessee, including the incorporated communities is not available since FIS reports have never been published for these communities. For this countywide FIS, new hydrologic and hydraulic analyses were performed by Watershed IV Alliance (the Study Contractor), for the Federal Emergency Management Agency (FEMA), under Contract No. EMA-2002-CO-0011A. Task Order No. 016. Base map information shown on this FIRM was derived from multiple sources. Base map information for LAKE County and all incorporated communities within LAKE County was provided in digital format by the State of Tennessee. This information was compiled from tax maps and aerial photography. The digital FIRMs were produced in Universal Transverse Mercator coordinates referenced to the North American Datum of 1988 and the Clarke 1866 spheroid.

cited responsible party - originator

organisation Name  Federal Emergency Management Agency

source

source description  Source Contribution: USGS Quad IndexSource Type online

source citation

Title USGS Quad Index

publication  Date   2002-01-01

cited responsible party - originator

organisation Name  USGS

source

source description  Source Contribution: BenchmarksSource Type online

source citation

Title Benchmarks

publication  Date   2006-11-29

cited responsible party - originator

organisation Name  NOAA, NGS

source

source description  Source Contribution: Incorporated CommunitiesSource Type online

source citation

Title Incorporated Communities

publication  Date   2006-10-30

cited responsible party - originator

organisation Name  State of Tennessee Department of Finance and Administration GIS Department

source

source description  Source Contribution: County BoundarySource Type online

source citation

Title County Boundary

publication  Date   2006-10-30

cited responsible party - originator

organisation Name  State of Tennessee Department of Finance and Administration GIS Department

source

source description  Source Contribution: TransportationSource Type online

source citation

Title Transportation

publication  Date   2006-10-30

cited responsible party - originator

organisation Name  State of Tennessee Department of Finance and Administration GIS Department

source

source description  Source Contribution: HydrologySource Type online

source citation

Title Hydrology

publication  Date   2006-10-30

cited responsible party - originator

organisation Name  State of Tennessee Department of Finance and Administration GIS Department

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.