DIGITAL FLOOD INSURANCE RATE MAP DATABASE, LAKE AND PENINSULA BOROUGH, AK, USA

Resource lineage description

source

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

representative resolution scale:

Scale denominator: 24000

source citation

Title USGS 7.5-Minute Series Topographic Maps

publication  Date   1989-01-01

presentationForm  DIGITAL VECTOR DATA

other Citation Details  USGS has mapped the county with 1:24,000 scale topographic maps (also referred to as 7.5-minute quadrangles). The entire county was mapped by the late 1980s. From the raster topographic maps, a vector index of the USGS topographic maps with its corresponding tile identification number and name was created.

cited responsible party - publisher

organisation Name  U.S. Geological Survey

Contact information

Address

, Reston, VA

cited responsible party - originator

organisation Name  U.S. Geological Survey

source

source description  Source Contribution: Spatial and attribute information for PLSS boundaries.Source Type online

representative resolution scale:

Scale denominator: 63360

source citation

Title secgrid

publication  Date   2001-02-07

presentationForm  mapDigital

other Citation Details  Township boundaries were generated from geodetic latitude and longitude coordinate pairs as recorded on BLM's official protraction diagrams of the state of Alaska. Section positions are computed from BLM official protraction diagrams based on township positions, subdivision shape codes, and parenthetical distances. The values used for this data were initially obtained from U.S., Department of the Interior, Bureau of Land Management, Alaska State Office, Division of Cadastral Survey and Geomatics's (BLM) AEH (acronym unknown) coordinate files.

cited responsible party - publisher

organisation Name  U.S. Dept. of Interior, Bureau of Land Management, Division of Cadastral Survey and Geomatics, Branch of Spatial Records

Contact information

Address

, Washington, DC

cited responsible party - originator

organisation Name  U.S. Dept. of Interior, Bureau of Land Management, Division of Cadastral Survey and Geomatics, Branch of Spatial Records

source

source description  Source Contribution: Spatial and attribute information for political boundaries.Source Type online

representative resolution scale:

Scale denominator: 63360

source citation

Title Incorporated City Boundaries of Alaska

publication  Date   2003-01-01

presentationForm  mapDigital

other Citation Details  This data contains the boundaries of incorporated cities according to the State of Alaska Department of Community and Economic Development (DECED). The city boundaries were updated from an older version of the data by various means. The primary source of information that was used for the creation of new boundaries was the legal descriptions found within the city certificates. Other means used included rectifying status plats, digitizing features found on USGS Topographic Quadrangle maps, and digital data availible for download from borough web sites. This data set was created using the Web Extraction Tool (WET) coverage offset, region.b_city as a base data set. With information provided by the State of Alaska Department of Community and Economic Development (DCED) the city boundaries coverage was created with new updates (i.e. dissolved cities, newly incorporated city boundaries, and city boundary changes). The editing and creation of the data set was mainly performed by the legal descriptions found in the city certificate. In the event that the legal description was absent and/or means of locating areas described in the legal description was not available, other actions of editing and creating the boundaries were taken (i.e. rectification and digitizing BLM and DNR Status Plats, digitizing known boundaries and features found on USGS Topographic Quadrangle maps, and simple edits of existing boundaries such as merge, join, delete, etc.).

cited responsible party - publisher

organisation Name  AK Department of Community and Economic Development

Contact information

Address

, Anchorage, AK

cited responsible party - originator

organisation Name  AK Department of Community and Economic Development

source

source description  Source Contribution: Spatial and attribute information for transportation features.Source Type CD-ROM

representative resolution scale:

Scale denominator: 9600

source citation

Title Road Centerlines Digitized from Orthoimagery

publication  Date   2007-12-01

presentationForm  mapDigital

other Citation Details  Road centerlines digitized from 2002 orthoimagery (BASE9, BASE10, BASE11). Attribute information obtained from online mapping site.

cited responsible party - publisher

organisation Name  L-3 Services, Inc.

Contact information

Address

, Portland, OR

cited responsible party - originator

organisation Name  L-3 Services, Inc.

source

source description  Source Contribution: Spatial and attribute information transportation features.Source Type CD-ROM

representative resolution scale:

Scale denominator: 9600

source citation

Title Airports Digitized from Orthoimagery

publication  Date   2007-12-01

presentationForm  mapDigital

other Citation Details  Airports digitized from 2002 orthoimagery (BASE9, BASE10, BASE11). Attribute information obtained from online mapping site.

cited responsible party - publisher

organisation Name  L-3 Services, Inc.

Contact information

Address

, Portland, OR

cited responsible party - originator

organisation Name  L-3 Services, Inc.

source

source description  Source Contribution: Spatial and attribute information for transportation features.Source Type online

representative resolution scale:

Scale denominator: 63360

source citation

Title Alaska Airstrips 1:63,360

publication  Date   2007-11-19

presentationForm  mapDigital

other Citation Details  This data depicts airstrip and runway locations in Alaska as digitized primarily from 1:24,000, 1:63,360, and 1:250,000 USGS quadrangles. The source document that represented the newest information and best geographic location was used to capture the data. All infrastructure from the primary source document was digitized and then supplemented with the information from other source documents for additional or updated infrastructure or attributes.

cited responsible party - publisher

organisation Name  Alaska Department of Natural Resources - Land Records Information Section

Contact information

Address

, Anchorage, AK

cited responsible party - originator

organisation Name  Alaska Department of Natural Resources - Land Records Information Section

source

source description  Source Contribution: Spatial and attribute information for water features.Source Type online

representative resolution scale:

Scale denominator: 63360

source citation

Title Alaska Hydrography 1:63360

publication  Date   2007-01-29

presentationForm  mapDigital

other Citation Details  DNR, LRIS, Status Graphics Unit (SGU) maintains a hydrography coverage consisting of data that was digitized by SGU staff, primarily from 1:63,360 USGS quadrangles photo-revised by BLM from aerial high altitude photography flown between 1978-1985. In addition, data from other sources was digitized or obtained in digital format if BLM data was not available..

cited responsible party - publisher

organisation Name  Alaska Department of Natural Resources-Land Records Information Section

Contact information

Address

, Anchorage, AK

cited responsible party - originator

organisation Name  Alaska Department of Natural Resources-Land Records Information Section

source

source description  Source Contribution: Base map features.Source Type CD-ROM

representative resolution scale:

Scale denominator: 9600

source citation

Title Chignik Bay 2002

publication  Date   2002-07-31

presentationForm  REMOTE SENSING IMAGE

other Citation Details  Digital Orthomosaic of Chignik Bay based on 31 July 2002 aerial photography with a pixel ground resolution of 1 foot. Aerial Photography Capture: A twin-engine aircraft with an on-board 6 (six) inch focal length film camera was used to capture 14 exposures along 3 (three) flight lines. Scanning Process: The photographic negatives were scanned on a photogrammetric scanner at a resolution 16 microns to produce pixels with a nominal ground distance of about 0.5039 feet. Aerotriangulation Process: The aerotriangulation was performed using GPS/IMU data and was refined using conventional photogrammetric methods. Orthorectification Process: The scanned images, aerotriangulation information, and DEM were processed using orthoimagery software to remove systematic and geographic distortions while georeferencing the scanned imagery. The resulting orthorectified images were then mosaicked and color balanced into a single image with a ground resolution of 1.0 foot.

cited responsible party - publisher

organisation Name  Aero-Metric, Anchorage

Contact information

Address

, Anchorage, AK

cited responsible party - originator

organisation Name  Aero-Metric, Anchorage

source

source description  Source Contribution: Base map features.Source Type CD-ROM

representative resolution scale:

Scale denominator: 9600

source citation

Title Chignik Lake 2002

publication  Date   2002-07-31

presentationForm  REMOTE SENSING IMAGE

other Citation Details  Digital Orthomosaic of Chignik Lake based on 31 July 2002 aerial photography with a pixel ground resolution of 1 foot. Aerial Photography Capture: A twin-engine aircraft with an on-board 6 (six) inch focal length film camera was used to capture 8 (eight) exposures along 1 (one) flight line. Scanning Process: The photographic negatives were scanned on a photogrammetric scanner at a resolution 16 microns to produce pixels with a nominal ground distance of about 0.5039 feet. Aerotriangulation Process: The aerotriangulation was performed using GPS/IMU data and was refined using conventional photogrammetric methods. Orthorectification Process: The scanned images, aerotriangulation information, and DEM were processed using orthoimagery software to remove systematic and geographic distortions while georeferencing the scanned imagery. The resulting orthorectified images were then mosaicked and color balanced into a single image with a ground resolution of 1.0 foot.

cited responsible party - publisher

organisation Name  Aero-Metric, Anchorage

Contact information

Address

, Anchorage, AK

cited responsible party - originator

organisation Name  Aero-Metric, Anchorage

source

source description  Source Contribution: Base map features.Source Type CD-ROM

representative resolution scale:

Scale denominator: 9600

source citation

Title Chignik Lagoon 2002

publication  Date   2002-07-31

presentationForm  REMOTE SENSING IMAGE

other Citation Details  Digital Orthomosaic of Chignik Lagoon based on 31 July 2002 aerial photography with a pixel ground resolution of 1 foot.Aerial Photography Capture: A twin-engine aircraft with an on-board 6 (six) inch focal length film camera was used to capture 8 (eight) exposures along 1 (one) flight line. Scanning Process: The photographic negatives were scanned on a photogrammetric scanner at a resolution 16 microns to produce pixels with a nominal ground distance of about 0.5039 feet. Aerotriangulation Process: The aerotriangulation was performed using GPS/IMU data and was refined using conventional photogrammetric methods. Orthorectification Process: The scanned images, aerotriangulation information, and DEM were processed using orthoimagery software to remove systematic and geographic distortions while georeferencing the scanned imagery. The resulting orthorectified images were then mosaicked and color balanced into a single image with a ground resolution of 1.0 foot.

cited responsible party - publisher

organisation Name  Aero-Metric, Anchorage

Contact information

Address

, Anchorage, AK

cited responsible party - originator

organisation Name  Aero-Metric, Anchorage

source

source description  Source Contribution: Spatial and attribute information for flood hazard features.Source Type CD-ROM

representative resolution scale:

Scale denominator: 6000

source citation

Title Delineated Flood Hazard Features for Lake & Peninsula Borough AK

publication  Date   2008-01-01

presentationForm  mapDigital

other Citation Details  Flood hazard features delineated from topographic data and orthoimagery.

cited responsible party - publisher

organisation Name  Northwest Hydraulic Consultants, Inc.

Contact information

Address

, Seattle, WA

cited responsible party - originator

organisation Name  Northwest Hydraulic Consultants, Inc.

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.