Land-Cover Data Derived from Landsat Satellite Imagery, Assateague Island to Metompkin Island, Maryland and Virginia, 1984 to 2014

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Frequently anticipated questions:

What does this data set describe?

Title:
Land-Cover Data Derived from Landsat Satellite Imagery, Assateague Island to Metompkin Island, Maryland and Virginia, 1984 to 2014
Abstract:
The U.S. Geological Survey has a long history of responding to and documenting the impacts of storms along the Nation’s coasts and incorporating these data into storm impact and coastal change vulnerability assessments. These studies, however, have traditionally focused on sandy shorelines and sandy barrier-island systems, without consideration of impacts to coastal wetlands. The goal of the Barrier Island and Estuarine Wetland Physical Change Assessment project is to integrate a wetland-change assessment with existing coastal-change assessments for the adjacent sandy dunes and beaches, initially focusing on Assateague Island along the Maryland and Virginia coastline. Assateague Island was impacted by waves and storm surge associated with the passage of Hurricane Sandy in October 2012, including erosion and overwash along the ocean-facing sandy shoreline as well as erosion and overwash deposition in the back-barrier and estuarine bay environments. This report serves as an archive of data that were derived from Landsat 5 and Landsat 8 imagery from 1984 to 2014, including wetland and terrestrial habitat extents; open-ocean, back-barrier, and estuarine mainland shoreline positions; and sand-line positions along the estuarine mainland and barrier shorelines from Assateague Island, Maryland to Metompkin Island, Virginia. The geographic information system data files with accompanying formal Federal Geographic Data Committee (FGDC) metadata can be downloaded from http://pubs.usgs.gov/ds/0968/ds968_data.html.
Supplemental_Information:
Information about the Landsat missions, sensor and band specifications, Level 1 data products, and data acess can be found at http://landsat.usgs.gov/index.php.
  1. How might this data set be cited?
    Bernier, Julie C., 2015, Land-Cover Data Derived from Landsat Satellite Imagery, Assateague Island to Metompkin Island, Maryland and Virginia, 1984 to 2014:.

    Online Links:

    This is part of the following larger work.

    Bernier, Julie C., Douglas, Steven H., Terrano, Joseph F., Barras, John A., Plant, Nathaniel G., and Smith, Christopher G., 2015, Land-Cover Types, Shoreline Positions, and Sand Extents Derived from Landsat Satellite Imagery, Assateague Island to Metompkin Island, Maryland and Virginia, 1984 to 2014: U.S. Geological Survey Data Series 968, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.590337
    East_Bounding_Coordinate: -74.993480
    North_Bounding_Coordinate: 38.327347
    South_Bounding_Coordinate: 37.739426
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 24-Nov-1984
    Currentness_Reference:
    Ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Raster digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 2169 x 1739 x 1, type Pixel
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75.0
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using Coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.001
      Ordinates (y-coordinates) are specified to the nearest 0.001
      Planar coordinates are specified in Meters
      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    lt5_p14r33_p14r34_a2a_lc_final.gdb
    Esri file geodatabase containing thematic raster datasets representing land-cover classes for each of 19 Landsat 5 image acquisition dates (Source: USGS)
    lc8_p14r33_p14r34_a2a_lc_final.gdb
    Esri file geodatabase containing thematic raster datasets representing land-cover classes for each of 4 Landsat 8 image acquisition dates (Source: USGS)
    OBJECTID
    Internal feature number (Source: Esri) Sequential unique whole numbers that are automatically generated
    Value
    Land-cover class number (Source: USGS)
    ValueDefinition
    0OUT - pixels outside of analysis extent
    1WATER - pixels classified as water
    4WET MARSH - pixels classified as wet marsh land cover
    6MARSH - pixels classified as marsh land cover
    7FORESTED - pixels classified as forested land cover
    8MIXED VEGETATION - pixels classified as mixed vegetation land cover
    10VEGETATED BARE EARTH - pixels classified as vegetated bare earth land cover
    11BARE EARTH - pixels classified as bare earth
    Description
    Land-cover description (Source: USGS)
    ValueDefinition
    OUTPixels outside of analysis extent
    WATERPixels classified as water
    WET MARSHPixels classified as wet marsh land cover
    MARSHPixels classified as marsh land cover
    FORESTEDPixels classified as forested land cover
    MIXED VEGETATIONPixels classified as mixed vegetation land cover
    VEGETATED BARE EARTHPixels classified as vegetated bare earth land cover
    BARE EARTHPixels classified as bare earth

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Julie C. Bernier
  2. Who also contributed to the data set?
    U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Julie Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov

Why was the data set created?

This zip archive includes thematic raster data representing land-cover classes derived from 19 Landsat 5 Thematic Mapper (TM) and four Landsat 8 Operational Land Imager (OLI) image datasets from Assateague Island to Metompkin Island, Maryland and Virginia. For each image acquisition date, the Level 1 data products were stacked into composite 6-band (visible blue, green, and red; near infrared; and two short-wave infrared bands) image files and converted to at-sensor radiance and top-of-atmosphere reflectance. Adjacent scenes (Worldwide Reference System 2, path 14 row 33 and path 14 row 34) were mosaicked to a single image and then clipped to the study area extent. Seven land-cover classes (water, wet marsh, marsh, forested, mixed vegetation, vegetated bare earth, and bare earth) were derived for each image acquisition date using a hybrid classification approach to minimize misclassification of small interior water bodies and tidal channels with surrounding marsh environments.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2014 (process 1 of 5)
    Each Landsat Level 1 data product was stacked into a composite multi-band image file using Intergraph Corporation ERDAS IMAGINE 2014 software. The six reflective bands (visible blue, green, and red; near infrared; and two short-wave infrared bands) for each sensor were stacked and used in subsequent processing and analyses. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Julie Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
    Date: 2014 (process 2 of 5)
    The composite multi-band image files were converted to at-sensor radiance and top-of-atmosphere (TOA) reflectance using Intergraph Corporation ERDAS IMAGINE 2014 software. Radiometric processing reduces scene-to-scene variability due to gain changes between scenes or differences in solar zenith angles, exoatmospheric solar irradiance, and the earth-sun distance resulting from different acquisition dates and times. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Julie Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
    Date: 2014 (process 3 of 5)
    For each image acquisition date, adjacent scenes (Worldwide Reference System 2, path 14 row 33 and path 14 row 34) were mosaicked to a single image and clipped to the study area extent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Julie Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
    Date: 2015 (process 4 of 5)
    Image classification was performed using Intergraph Corporation ERDAS IMAGINE 2014 software. A hybrid classification approach was used to minimize misclassification of small interior water bodies and tidal channels with surrounding marsh environments: (1) A 3×3 (pixel) edge enhancement convolution filter was applied to the radiometrically corrected, mosaicked images to enhance small water features; (2) Unsupervised classification was performed on the edge-enhanced image to identify and extract water areas; (3) Water areas from (2) were masked from the non edge-enhanced image and unsupervised classification of the remaining pixels was grouped into seven classes (water, wet marsh, marsh, forested, mixed vegetation, vegetated bare earth, and bare earth); and (4) Results of (2) and (3) were merged to generate a final thematically classified raster dataset. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Julie Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
    Date: 13-Oct-2020 (process 5 of 5)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Guy, Kristy K., 2015, Back-island and open-ocean shorelines, and sand areas of Assateague Island, Maryland and Virginia, April 12, 1989, to September 5, 2013: U.S. Geological Survey Data Series 928, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Geodetic accuracy of the Standard Terrain Correction (Level 1T) data product depends on the accuracy of the ground control points and the resolution of the DEM used.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Nineteen Landsat 5 Thematic Mapper (TM) and four Landsat 8 Operational Land Imager (OLI) image acquisition dates were selected for analysis. Image acquisition dates correspond to 5-year intervals beginning in 1984 supplemented with additional images from intervening years for which high-resolution aerial photography was also analyzed (Guy, 2015). If available, spring (April preferred) and late fall (November preferred) image acquisition dates were used for each analysis year. The spring and fall images were supplemented with additional scenes corresponding to aerial photography acquisition dates (Guy, 2015). A gap in imagery dates from August 31, 2011 to April 14, 2013, corresponding to the decommissioning of the Landsat 5 TM mission and the first data available from the recently launched Landsat 8 OLI mission. Data from the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) satellite are available for this time period; however, data gaps exist over the study area in all Landsat 7 images acquired since May 2003 due to the failure of the scan line corrector early in May 2003, limiting the use of these Landsat 7 data in quantitative land-change analyses.
  5. How consistent are the relationships among the observations, including topology?
    Landsat standard data products, processed using the Level 1 Product Generation System (LPGS), were downloaded from the USGS Earth Resources Observation and Science (EROS) Center data archives. Even after using a hybrid classification approach, some areas that were classified as wet marsh in the final thematic raster dataset appeared, upon visual inspection, to include submerged aquatic vegetation and submerged sand flats that would be more appropriately classified as open water. These ambiguities are not consistent through time but most commonly occur in Sinepuxent Bay south of Ocean City Inlet, north of Green Run Bay and Pirate Islands, in impoundments behind Chincoteague Island, and at Chincoteague Inlet. Similarly, in some instances, areas that were classified as water in the final thematic raster dataset were interpreted as wet sand on visual inspection. This most commonly occurs along the narrowest part of Assateague Island south of Ocean City Inlet, at the Tom’s Cove spit, and along Metompkin Island. Additionally, some near-shore estuarine areas exhibit “speckling” caused by misclassification of isolated higher reflectance pixels within the water body. No manual cleaning of open-water speckling or potentially misclassified pixels was performed.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
The U.S. Geological Survey requests that it be acknowledged as the originator of this dataset in any future products or research derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: Julie Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable data
  3. What legal disclaimers am I supposed to read?
    This publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: This zip file contains two file geodatabases, one each for the Landsat 5 and Landsat 8 thematic land-cover rasters, and this metadata. in format Esri file geodatabase (version 10.2.2) Raster dataset Size: 3.12
      Network links: http://pubs.usgs.gov/ds/0968/downloads/landsat_a2a_lc_final.zip
    • Cost to order the data: None, if obtained online

  5. What hardware or software do I need in order to use the data set?
    These file geodatabase raster datasets were created using Esri ArcGIS version 10.2.2 and can be opened using Esri ArcGIS version 10.0 or higher; these data may also be viewed using the free GIS viewer ArcGIS Explorer.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
U.S. Geological Survey
Attn: Julie Bernier
Geologist
600 4th Street South
St. Petersburg, FL
USA

727-502-8000 (voice)
jbernier@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/DS968_landsat_a2a_lc_final-met.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:49 2021