DIGITAL FLOOD INSURANCE RATE MAP DATABASE, LEA COUNTY, NM, USA

Resource lineage description

source

source description  Source Contribution: Spatial and attribute information, floodplain widths, BFEs, cross sections, water features, floodplain location.Source Type digital tape media

source citation

Title DIGITAL FLOOD INSURANCE RATE MAP DATABASE, LEA COUNTY, NEW MEXICO AND INCORPORATED AREAS

publication  Date   2005-12-16

presentationForm  mapDigital

cited responsible party - originator

organisation Name  Federal Emergency Management Agency

source

source description  Source Contribution: spatial and attribute information for political boundaries, and township, range and section information (plss).Source Type online

source citation

Title New Mexico Base

publication  Date   2004-08-02

cited responsible party - originator

organisation Name  New Mexico Resource Information System Program

source

source description  Source Contribution: spatial and attribute information for street centerlines. Street centerlines are provided by Lea County 911 and were compiled from GPS units between 2000 and 2002. Although the quantitative horizontal accuracy is not known, based upon the collection method, the street centerlines should meet or exceed FEMA accuracy requirements of 38 feet.Source Type vector digital data

source citation

Title Transportation File

publication  Date   2002-06-20

cited responsible party - originator

organisation Name  Lea County 911

source

source description  Source Contribution: Spatial and attribute information for the index of USGS 7.5-Minute Series Topographic Map boundaries.Source Type online

source citation

Title USGS 7.5-Minute Series Topographic Maps

publication  Date   2008-12-16

cited responsible party - originator

organisation Name  U.S. Geological Survey

source

source description  Source Contribution: spatial and attribute information for benchmarks.Source Type online

source citation

Title Horizontal and Vertical Geodetic Control Data

publication  Date   2004-01-01

cited responsible party - originator

organisation Name  NOAA, National Geodetic Survey

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.