# NLCD 2001 Percent Developed Imperviousness (2011 Edition, amended 2014) - National Geospatial Data Asset (NGDA) Land Use Land Cover, 3 x 3 Degree: NLCD2001_IMP_N27W078

Metadata also available as

# Metadata:

- Identification_Information
- Data_Quality_Information
- Spatial_Data_Organization_Information
- Spatial_Reference_Information
- Entity_and_Attribute_Information
- Distribution_Information
- Metadata_Reference_Information

Identification_Information:
  Citation:
    Citation_Information:
      Originator: U.S. Geological Survey
      Publication_Date: 20141010
      Title:
        NLCD 2001 Percent Developed Imperviousness (2011 Edition, amended 2014) - National Geospatial Data Asset (NGDA) Land Use Land Cover, 3 x 3 Degree: NLCD2001_IMP_N27W078
      Edition: 2011
      Geospatial_Data_Presentation_Form: remote-sensing image
      Series_Information:
        Series_Name: None
        Issue_Identification: None
      Publication_Information:
        Publication_Place: Sioux Falls, SD
        Publisher: U.S. Geological Survey
      Other_Citation_Details:
        References: Yang, L, C. Huang, C. Homer, B. Wylie, and M. Coan, 2003. An approach for mapping large-area impervious surfaces: Synergistic use of Landsat 7 ETM+ and high spatial resolution imagery. Canadian Journal of Remote Sensing, 29: 2, 230-240. Homer, C., C. Huang, L. Yang, B. Wylie and M. Coan, 2004. Development of a 2001 national land cover database for the United States. Photogrammetric Engineering and Remote Sensing.
      Online_Linkage:
        <http://gisdata.usgs.gov/tdds/downloadfile.php?TYPE=nlcd2001_imp_3x3&ORIG=META&FNAME=NLCD2001_IMP_N27W078.zip>
      Online_Linkage:
        <http://tdds.cr.usgs.gov/metadata/nlcd/2001/impervious/conus/NLCD2001_IMP_N27W078.htm>
      Online_Linkage: <http://nationalmap.gov/viewer.html>
  Description:
    Abstract:
      The National Land Cover Database 2001 Percent Developed Imperviousness was produced through a cooperative project conducted by the Multi-Resolution Land Characteristics (MRLC) Consortium. The MRLC Consortium is a partnership of federal agencies (www.mrlc.gov), consisting of the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the U.S. Environmental Protection Agency (EPA), the U.S. Department of Agriculture - Forest Service (USDA-FS), the National Park Service (NPS), the U.S. Fish and Wildlife Service (FWS), the Bureau of Land Management (BLM) and the USDA Natural Resources Conservation Service (NRCS).
      One of the primary goals of the project is to generate a current, consistent, seamless, and accurate National Land Cover Database (NLCD) circa 2001 for the United States at medium spatial resolution. For a detailed definition and discussion on MRLC and the NLCD 2001 products, refer to Homer et al. (2003) and <http://www.mrlc.gov/mrlc2k.asp>.
      The NLCD 2001 was created by partitioning the U.S. into mapping zones. A total of 66 mapping zones were delineated within the conterminous U.S. based on ecoregion and geographical characteristics, edge-matching features and the size requirement of Landsat mosaics. This update represents a seamless assembly of updated NLCD 2001 Percent Developed Imperviousness for all 66 MRLC mapping zones. Questions about the NLCD 2001 Percent Developed Imperviousness 2011 Edition can be directed to the NLCD 2001 land cover mapping team at USGS EROS, Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov.
    Purpose:
      The goal of this project is to provide the Nation with complete, current and consistent public domain information on its land use and land cover.
    Supplemental_Information:
      Corner Coordinates (center of pixel, projection meters) Upper Left Corner: -2493045 meters(X), 3310005 meters(Y) Lower Right Corner: -177285 meters(X), 2342655 meters(Y)
  Time_Period_of_Content:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: 19990428
        Ending_Date: 20040726
    Currentness_Reference: ground condition
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: Every 5 years
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -81
      East_Bounding_Coordinate: -78
      North_Bounding_Coordinate: 30
      South_Bounding_Coordinate: 27
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: NGDA Portfolio Themes
      Theme_Keyword: NGDA
      Theme_Keyword: National Geospatial Data Asset
      Theme_Keyword: Land Use Land Cover Theme
    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: Imperviousness
      Theme_Keyword: GIS
      Theme_Keyword: U.S. Geological Survey
      Theme_Keyword: USGS
      Theme_Keyword: digital spatial data
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: imageryBaseMapsEarthCover
      Theme_Keyword: 010
    Place:
      Place_Keyword_Thesaurus:
        U.S. Department of Commerce, 1995, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions, Federal Information Processing Standard 10-4,): Washington, D.C., National Institute of Standards and Technology
      Place_Keyword: United States
      Place_Keyword: U.S.
      Place_Keyword: US
  Access_Constraints: None
  Use_Constraints: None
  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
      Contact_Position: Customer Services Representative
      Contact_Address:
        Address_Type: mailing and physical
        Address: USGS EROS
        Address: 47914 252nd Street
        City: Sioux Falls
        State_or_Province: SD
        Postal_Code: 57198-0001
        Country: USA
      Contact_Voice_Telephone: 605/594-6151
      Contact_TDD/TTY_Telephone: 605/594-6933
      Contact_Facsimile_Telephone: 605/594-6589
      Contact_Electronic_Mail_Address: custserv@usgs.gov
      Hours_of_Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
      Contact_Instructions:
        The USGS point of contact is for questions relating to the data display and download from this web site. For questions regarding data content and quality, refer to: <http://www.mrlc.gov/mrlc2k.asp> or email: mrlc@usgs.gov
  Browse_Graphic:
    Browse_Graphic_File_Name:
      <http://tdds.cr.usgs.gov/browse/nlcd/2001/impervious/conus/NLCD2001_IMP_N27W078.jpg>
    Browse_Graphic_File_Description: Tiled NLCD Browse Image
    Browse_Graphic_File_Type: JPEG
  Data_Set_Credit: U.S. Geological Survey
  Security_Information:
    Security_Classification_System: None
    Security_Classification: Unclassified
    Security_Handling_Description: N/A
  Native_Data_Set_Environment:
    Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; ESRI ArcCatalog 9.3.1.4000

Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
      The information on data quality for NLCD 2001 Percent Developed Imperviousness 2011 Edition seamless data product was generated by the Regression Tree algorithm that conducts a cross-validation for assessing classification and prediction reliability. No formal independent accuracy assessment for this product has been made. The regression tree algorithm employed in NLCD 2001 mapping protocols offers a cross-validation option for assessing classification and prediction reliability. Cross-validation can provide relatively reliable estimates for imperviousness predictions if the reference data used for cross-validation are collected based on a statistically valid sampling design. For each mapping zone, a 5-fold cross-validation was conducted by dividing the entire training data set into 5 subsets of equal size. For each model run, an accuracy estimate was derived using one subset to evaluate the model prediction (with the model developed using the remaining training samples). This process was repeated 5 times. After all 5 runs, an average value of all accuracy estimates from the 5 runs was computed. Users should be cautioned that these cross-validation results provide users with only first-order estimates of data quality, and should not be considered a formal accuracy assessment.
    Quantitative_Attribute_Accuracy_Assessment:
      Attribute_Accuracy_Value: 87.6
      Attribute_Accuracy_Explanation:
        The above listed value is the mean accuracy obtained for imperviousness data in cross-validation studies for all 66 MRLC Zones. The table below provides individual zone accuracy values derived from protocols described in the accuracy report above. MRLC Zone Imperviousness Accuracy 1 86.2 2 86.7 3 89 4 90 5 85.8 6 90 7 83 8 86.7 9 85.6 10 86.1 12 85.4 13 89.5 14 93 15 93 16 80 17 87 18 88.1 19 82 20 87.3 21 92.7 22 83.8 23 85 24 87 25 88 26 91 27 90 28 86 29 89 30 88.2 31 85.6 32 91.8 33 90 34 87 35 91 36 88 37a 91 37b 91 38 89 39 88.2 40 86.5 41 85.8 42 86.5 43 85.4 44 92 45 95 46a 86 46b 86 47 81 48 85 49 85 50 90 51 89 52 88 53 71 54 84 55 85 56 90 57 84 58 82 59 86 60 91 61 86.5 62 90.5 63 95 64 93 65 92 66 88
  Logical_Consistency_Report:
    The method employed to map percent developed imperviousness for NLCD 2001 consists of three key steps: deriving reference data of imperviousness from the high spatial resolution images, calibrating density prediction models using reference data and Landsat spectral bands, and extrapolating the developed models spatially to map per-pixel imperviousness.
  Completeness_Report:
    This NLCD 2001 Percent Developed Imperviousness data product is the version dated October 10, 2014.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report: N/A
    Vertical_Positional_Accuracy:
      Vertical_Positional_Accuracy_Report: N/A
  Lineage:
    Process_Step:
      Process_Description:
        The method employed to map percent developed imperviousness for NLCD 2001 consists of three key steps: deriving reference data of imperviousness from the high spatial resolution images, calibrating density prediction models using reference data and Landsat spectral bands, and extrapolating the developed models spatially to map per-pixel imperviousness. This method is described in detail in Yang et al. (2003).
      Process_Date: Unknown
    Process_Step:
      Process_Description:
        To develop adequate training data for impervious estimation, approximately 20 DOQQ's across each mapping zone with a nominal spatial resolution of 1-m were classified into either pervious or non-pervious surfaces, and then summed within each 30 meter Landsat pixel cell to obtain percentage of imperviousness. Training data were selected based on the degree of variance each training data set possesses with regards to Landsat ETM+ imagery used for mapping. Each added training data set decreased the amount of variance present within the Landsat data as a whole. The selection process was repeated until the amount of variance explained reached a pre-defined threshold. By combining the training data with Landsat spectral data and other ancillary data, percent imperviousness prediction models were developed using a regression tree algorithm (named "Cubist"). All data layers used as input for running the Cubist, in order to establish the prediction model for imperviousness are listed in the "Supplemental Information" section. Three ancillary data sets were used for urban/suburban delineation masking, which is essential to confine the imperviousness mapping within the developed areas. After the best combination of possible input data layers had been determined and the final percent impervious layer produced, the urban mask created was used to eliminate those pixels from the final percent impervious file that fall outside identified impervious surface areas. Thus, the impervious pixels identified within the mask were retained, while all non-impervious surface pixels were removed from the final product. This corrected for any small areas of pixels that may have been included as part of the impervious surface layer because their spectral signature was not covered in the Cubist modeling process. Finally, visual inspection of imperviousness layer was made with limited manual editing to eliminate non-urban areas based on area of interest delineated by the mapping team. For Landsat Scene Acquisition dates and identification numbers for imagery used in the NLCD 2001 land, please see: appendix2_nlcd2001_scene_list_by_zone.txt
      Source_Used_Citation_Abbreviation: Landsat ETM, DEM
      Process_Date: Unknown
      Source_Produced_Citation_Abbreviation: USGS NLCD
    Process_Step:
      Process_Description:
        NLCD 2001 Impervious (2011 Edition) Processing To improve NLCD imperviousness the 2011 project included a process to reduce omission and commission error in NLCD 2001, 2006, and 2011 products. This activity was completed for urban areas in most of the eastern of the conterminous United States. High resolution (one-meter ground sample distance) National Aerial Imagery Program (NAIP <http://fsa.usda.gov/FSA/>) imagery was used to verify imperviousness. Using hand-edits imperviousness was removed from areas incorrectly identified as developed and added to areas where developed land cover was missed. A modeling process was implemented to parse imperviousness changes to the correct era. These improvements were incorporated with the derived developed classes in all areas of imperviousness and land cover versions released with NLCD 2011 editions.
      Process_Date: Unknown
    Process_Step:
      Process_Description:
        Process Step for NLCD 2001 Percent Developed Imperviousness (2011 edition, amended 2014): The release in 2014 of amended versions of Imperviousness for 2001, 2006, and 2011 was made to correct for unintended differences between the impervious dataset and the four land cover developed classes (Open Space, Low Intensity, Medium Intensity, and High Intensity). NLCD developed classes are tied directly to the impervious product values. However, the land cover product Minimum Mapping Unit (MMU) is five pixels whereas the impervious product MMU is single pixel. This MMU difference creates problems when the impervious single pixel MMU product is directly crosswalked into the 5-pixel MMU land cover developed classes. The smoothing process, which generalizes the land cover product to a 5-pixel MMU, can create small areas which are no longer directly represented in the imperviousness product because they are artifacts of the smoothing. Since these changes are not real and not present in the impervious layer, the new version removes these artifacts and re-establishes the direct linkage between the imperviousness and land cover products for any developed area. Combined developed areas (all developed classes combined into a group) in the land cover product must still meet the 5-pixel MMU threshold; however, the four NLCD land cover individual developed classes within the group patch are now represented by a single pixel MMU to retain the direct linkage to the imperviousness product.
      Process_Date: Unknown

Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type: Pixel
    Row_Count: 12585
    Column_Count: 11575
    Vertical_Count: 1

Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Map_Projection:
        Map_Projection_Name: Albers Conical Equal Area
        Albers_Conical_Equal_Area:
          Standard_Parallel: 29.500000
          Standard_Parallel: 45.500000
          Longitude_of_Central_Meridian: -96.000000
          Latitude_of_Projection_Origin: 23.000000
          False_Easting: 0.000000
          False_Northing: 0.000000
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 30.000000
          Ordinate_Resolution: 30.000000
        Planar_Distance_Units: meters
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: Geodetic Reference System 80
      Semi-major_Axis: 6378137.0
      Denominator_of_Flattening_Ratio: 298.2572221

Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: nlcd_2001_impervious_2011_edition_2014_10_10.img.vat
      Entity_Type_Definition: NLCD Imperviousness Layer
      Entity_Type_Definition_Source: National Land Cover Database 2001
    Attribute:
      Attribute_Label: ObjectID
      Attribute_Definition: Internal feature number
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain:
          Sequential unique whole numbers that are automatically generated.
    Attribute:
      Attribute_Label: Value
      Attribute_Definition: Percent Imperviousness
      Attribute_Definition_Source: NLCD 2001
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 100
          Attribute_Units_of_Measure: percentage
          Attribute_Measurement_Resolution: 0.1
    Attribute:
      Attribute_Label: Count
      Attribute_Definition:
        A nominal integer value that designates the number of pixels that have each value in the file; histogram column in ERDAS Imagine raster attributes table
      Attribute_Definition_Source: NLCD 2001
      Attribute_Domain_Values:
        Unrepresentable_Domain: Integer
    Attribute:
      Attribute_Label: Red
      Attribute_Definition:
        Red color code for RGB slice by value for imperviousness image display purposes. The value is arbitrarily assigned by the display software package, unless defined by user. Standard user defined ramp for NLCD project is start color light gray, end color red.
      Attribute_Definition_Source: NLCD 2001
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 100
          Attribute_Units_of_Measure: CSS Color Value Percentage
          Attribute_Measurement_Resolution: 0.1
    Attribute:
      Attribute_Label: Green
      Attribute_Definition:
        Green color code for RGB slice by value for imperviousness image display purposes. The value is arbitrarily assigned by the display software package, unless defined by user. Standard user defined ramp for NLCD project is start color light gray, end color red.
      Attribute_Definition_Source: NLCD 2001
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 100
          Attribute_Units_of_Measure: CSS Color Value Percentage
          Attribute_Measurement_Resolution: 0.1
    Attribute:
      Attribute_Label: Blue
      Attribute_Definition:
        Blue color code for RGB slice by value for imperviousness image display purposes. The value is arbitrarily assigned by the display software package, unless defined by user. Standard user defined ramp for NLCD project is start color light gray, end color red.
      Attribute_Definition_Source: NLCD 2001
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 100
          Attribute_Units_of_Measure: CSS Color Value Percentage
          Attribute_Measurement_Resolution: 0.1
    Attribute:
      Attribute_Label: Opacity
      Attribute_Definition:
        A measure of how opaque, or solid, a color is displayed in a layer.
      Attribute_Definition_Source: NLCD 2001
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 100
          Attribute_Units_of_Measure: Percentage
          Attribute_Measurement_Resolution: 0.1
  Overview_Description:
    Entity_and_Attribute_Overview: Imperviousness Attributes
    Entity_and_Attribute_Detail_Citation: Attributes defined by USGS and ESRI.

Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
      Contact_Position: Customer Services Representative
      Contact_Address:
        Address_Type: mailing and physical
        Address: USGS National Geospatial Program Office
        Address: 12201 Sunrise Valley Drive
        City: Reston
        State_or_Province: VA
        Postal_Code: 20192
        Country: USA
      Contact_Voice_Telephone: 1-888-ASK-USGS (1-888-275-8747)
      Contact_Electronic_Mail_Address: tnm_help@usgs.gov
      Hours_of_Service: Monday through Friday 8:00 AM to 4:00 PM Eastern Time Zone USA
      Contact_Instructions: Please visit <http://www.usgs.gov/ask/> to contact us.
  Resource_Description: Downloadable Data
  Distribution_Liability:
    Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty. Data may have been compiled from various outside sources. Spatial information may not meet National Map Accuracy Standards. This information may be updated without notification. The USGS shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results.
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: TIFF
        Transfer_Size: 5.455997
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name:
                <http://gisdata.usgs.gov/tdds/downloadfile.php?TYPE=nlcd2001_imp_3x3&ORIG=META&FNAME=NLCD2001_IMP_N27W078.zip>
          Access_Instructions:
            The URL <http://nationalmap.gov/viewer.html> provides a map interface that allows for viewing and data downloads within a customer defined area of interest. Zoom tools are available that can be used to investigate areas of interest on the map interface. The download tool allows the customer to capture layers from the map, utilizing The National Map process for downloading. The file can be unzipped and imported into various user software applications.
          Online_Computer_and_Operating_System: Not available for dissemination
    Fees: None
    Turnaround: Variable
  Technical_Prerequisites:
    ESRI ArcGIS Suite and/or Arc/Info or other compatible software, and supporting operating systems
  Available_Time_Period:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: 2014
        Ending_Date: Unknown

Metadata_Reference_Information:
  Metadata_Date: 20141205
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
        Contact_Person: Customer Services Representative
      Contact_Position: Customer Services Representative
      Contact_Address:
        Address_Type: mailing and physical
        Address: USGS EROS
        Address: 47914 252nd Street
        City: Sioux Falls
        State_or_Province: SD
        Postal_Code: 57198-0001
        Country: USA
      Contact_Voice_Telephone: 605/594-6151
      Contact_TDD/TTY_Telephone: 605/594-6933
      Contact_Facsimile_Telephone: 605/594-6589
      Contact_Electronic_Mail_Address: custserv@usgs.gov
      Hours_of_Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
  Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Time_Convention: local time
  Metadata_Access_Constraints: None
  Metadata_Use_Constraints: None

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