DIGITAL FLOOD INSURANCE RATE MAP DATABASE, Douglas COUNTY, Nevada

Resource lineage description

source

source description  Source Contribution: Spatial and attribute information for flood hazard features taken from effective FIRM including: DFIRM Panel Index (S_FIRM_Pan) Hydrologic Features (S_Wtr_Ln and S_Wtr_Ar), Hydrualic Structures (S_Gen_Struct), Flood Hazard Areas (S_Fld_Haz_Ar & S_Fld_Haz_Ln), Base Flood Elevations (S_BFE), Cross Sections (S_XS).Source Type Paper, CD-ROM

source citation

Title Flood Insurance Study Report and Flood Insurance Rate Maps, Douglas County, Nevada and Incorporated areas.

publication  Date   1999-01-01

cited responsible party - originator

organisation Name  Federal Emergency Management Agency

source

source description  Source Contribution: Spatial and attribute information for various base map and flood hazard features including: Transportation (S_Trans_Ln), Political Boundaries for Douglas County (S_Pol_Ar and S_Pol_Ln), Public Land Survey System (S_PLSS_AR and S_PLSS_LN), Irrigration and drainage features for the Carson River Valley (S_Wtr_Ln, S_Wtr_Ar, and S_Gen_Struct), Flood Hazard Areas (S_Fld_Haz_Ar & S_Fld_Haz_Ln), Base Flood Elevations (S_BFE), Letters of Map Change (S_LOMR). Publication Dates include 1994, 1996 and 2000.Source Type Digital Vector Data

source citation

Title Community Map Information, Douglas County, Nevada

publication  Date   2000-01-01

cited responsible party - originator

organisation Name  Multi-Agency Geographic Information Center (MAGIC), 1615 8th St, P.O.Box 218, Minden, Nevada, 89423

source

source description  Source Contribution: Spatial and attribute information for permanent benchmarks (S_PERM_BMK).Source Type Online

source citation

Title NGS Benchmarks, Douglas County, Nevada

publication  Date   2004-01-01

cited responsible party - originator

organisation Name  National Geodetic Survey

source

source description  Source Contribution: Background Orthoimagery Mosaic of Douglas County, Nevada. Location and layout of orginal orthophotopgrahy (S_Base_Index). Imagery was also used to correct the location of other base map features.Source Type Digital Aerial Photography

source citation

Title National Agriculture Imagery Program (NAIP), Douglas County, Nevada

publication  Date   2007-02-08

cited responsible party - originator

organisation Name  USDA-FSA-APFO Aerial Photography Field Office

source

source description  Source Contribution: Spatial and Attribute Information of Hydrologic Features (S_Wtr_Ln and S_Wtr_Ar)Source Type Online

source citation

Title National Hydrography Data Set (NHD), Douglas County, Nevada

publication  Date  

cited responsible party - originator

organisation Name  U.S. Geological Survey

source

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

source citation

Title USGS 7.5-Minute Series Topographic Maps

publication  Date   1989-01-01

cited responsible party - originator

organisation Name  U.S. Geological Survey

source

source description  Source Contribution: Spatial and attribute information for Flood Hazard Areas and Features used for appeals and updates. Dataset Includes: Flood Hazard Areas (S_Fld_Haz_Ar & S_Fld_Haz_Ln), Base Flood Elevations (S_BFE), Cross Sections (S_XS), Letters of Map Change (S_LOMR). Publication Dates include various dates from 1996 to 2007.Source Type Online

source citation

Title Letter of Map Change, Douglas County, Nevada

publication  Date   2007-01-01

other Citation Details  The Letter of Map Change (LOMC) states new data submitted to and accepted by FEMA that revises an area on the published FIS and/or FIRMs. These LOMCs were incorporated into the new effective FIS and FIRMs

cited responsible party - originator

organisation Name  Federal Emergency Management Agency

source

source description  Source Contribution: Spatial and attribute information for Flood Hazard Areas and Features in a complete Flood Insurance restudy of 11 streams in Douglas County. Dataset Includes: Flood Hazard Areas (S_Fld_Haz_Ar & S_Fld_Haz_Ln), Base Flood Elevations (S_BFE), Cross Sections (S_XS).Source Type CD-ROM

source citation

Title Flood Insurance Restudy of....Douglas County, Nevada

publication  Date   2005-02-01

cited responsible party - originator

organisation Name  Northwest Hydrualic Consultants, 3950 Industrial Blvd, Suite 100C, West Sacramento, California, 95691

source

source description  Source Contribution: Spatial and attribute information for Flood Hazard Areas and Features in a complete stream redelineation of 12 streams in Douglas County. Data derived from LiDAR data with 1 ft contours. Additionally a datum converision from NGVD29 to NAVD88 was applied to all BFE's from Source Citations FIS1, BASE1, BASE6 and STUDY1. Dataset Includes: Flood Hazard Areas (S_Fld_Haz_Ar & S_Fld_Haz_Ln), Base Flood Elevations (S_BFE),Source Type Digital Vector Data

source citation

Title Flood Insurance Study of Douglas County, Nevada

publication  Date   2010-01-20

cited responsible party - originator

organisation Name  Map IX

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.