Bathymetric change map of the nearshore around Ship, Horn, and Petit Bois islands, Mississippi: 2008-2009 to 2016

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Frequently anticipated questions:

What does this data set describe?

Title:
Bathymetric change map of the nearshore around Ship, Horn, and Petit Bois islands, Mississippi: 2008-2009 to 2016
Abstract:
To characterize coastal change, historical maps and complementary records were compiled including: topographic sheets (T-sheets), hydrographic sheets (H-sheets, smooth sheets), shorelines, and bathymetric soundings surrounding the Mississippi (MS) barrier islands over several time periods (1916-1920, 2008-2009 and 2016). One goal of this work was to create a time-series of bathymetric change maps around the islands. Data sets include 1916 through 1920 soundings collected by the United States Coast and Geodetic Survey as downloaded H-sheets and some digitized soundings from the National Oceanic and Atmospheric Administration (NOAA), 2008 to 2009 soundings collected by the United States Geological Survey St. Petersburg and Woods Hole Coastal and Marine Science Centers (USGS SPCMSC and WHCMSC, respectively), and 2016 soundings collected by the USGS SPCMSC in the nearshore environment of Ship, Horn, and Petit Bois Islands. This USGS data release includes three interpolated bathymetric change maps created by comparing the 1916 to 1920, 2008 to 2009, and 2016 bathymetry data; however, this metadata file pertains to the bathymetric change digital elevation model (DEM) observed between the 2008-2009 and 2016 bathymetry (2016minus2008to2009_MS_NAD83NAVD88g12B_50m.tif). This work was completed in cooperation with the United States Army Corps of Engineers (Mobile, Alabama) and the National Park Service as part of the Mississippi Coastal Improvements Program (MsCIP).
Supplemental_Information:
Elevation XYZ data used to create the 2008 to 2009 DEM are included in this USGS data release; 2016 XYZ data can be downloaded from DeWitt and others, 2017. The 2008 to 2009 elevation (z) values were adjusted to account for sea-level rise, using the NOAA tide gauge at Pensacola, FL. For further information on XYZ processing, refer to the accompanying elevation point metadata and Dewitt and others (2017). Within ArcGIS 10.4.1, XYZ soundings for 2008-2009 and 2016 were used to create Triangular Irregular Network (TIN) surfaces, individual TIN surfaces were later utilized to create a time-series of 50-m bathymetric rasters. A common snap raster was used to create these DEMs to maximize accuracy of subsequent bathymetric change map calculation. Bathymetric change maps were created using the 'Raster Calculator' and subtracting the one DEM from another. All spatial files provided in this data release are referenced to the Universal Transverse Mercator (UTM) North American Datum (NAD83) horizontal datum and North American Vertical Datum of 1988 (NAVD88) GEOID12B.
  1. How might this data set be cited?
    Buster, Noreen A., Brenner, Owen T., and Flocks, James G., 20171121, Bathymetric change map of the nearshore around Ship, Horn, and Petit Bois islands, Mississippi: 2008-2009 to 2016: U.S. Geological Survey Data Release doi:10.5066/F7028QFV, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -89.001779
    East_Bounding_Coordinate: -88.499847
    North_Bounding_Coordinate: 30.266217
    South_Bounding_Coordinate: 30.187818
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2008
    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 159 x 964, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 16
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -87.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 50
      Ordinates (y-coordinates) are specified to the nearest 50
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum 1988 GEOID12B
      Altitude_Resolution: 0.0001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Noreen A. Buster
    • Owen T. Brenner
    • James G. Flocks
  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?
    Noreen A. Buster
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

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

Why was the data set created?

The purpose of this effort was to create bathymetric grids and bathymetric change maps around the MS barrier islands to broadly characterize subaqueous morphologic change both spatially and temporally.

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: Jul-2017 (process 1 of 2)
    Using Esri ArcGIS 10.4.1, elevation pixel values from the 2008-2009 bathymetry DEM (2008_2009_MS_NAD83NAVD88g12B_50m.tif) were subtracted from co-located elevation pixel values of the 2016 bathymetry DEM pixel values (2016_MS_NAD83NAVD88g12B_50m.tif) using the 'Raster Calculator' tool. The resulting bathymetric change DEM was saved as a TIFF raster file (.tif) and associated TIFF worldfile (.tfw). Person who carried out this activity:
    Noreen A. Buster
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    nbuster@usgs.gov
    Date: 13-Oct-2020 (process 2 of 2)
    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?
    DeWitt, Nancy T., Flocks, James G., Pendleton, Elizabeth A., Hansen, Mark E., Reynolds, B.J., Kelso, Kyle W., Wiese, Dana S., and Worley, Charles R., 2012, Archive of single beam and swath bathymetry data collected nearshore of the Gulf Islands National Seashore, Mississippi, from West Ship Island, Mississippi, to Dauphin Island, Alabama: Methods and data report for USGS Cruises 08CCT01 and 08CCT02, July 2008, and 09CCT03 and 09CCT04, June 2009: U.S. Geological Survey Data Series DS 675, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

    DeWitt, Nancy T., Stalk, Chelsea A., Fredericks, Jake J., Flocks, James G., Kelso, Kyle W., Farmer, Andrew S., Tuten, Thomas M., and Buster, Noreen A., 2017, Coastal bathymetry data collected in 2016 nearshore from West Ship Island to Horn Island, Gulf Islands National Seashore, Mississippi: U.S. Geological Survey Data Release doi:10.5066/F7B8571Q, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

    Weber, Kathryn M., List, Jeffrey H., and Morgan, Karen L.M., 2005, An Operational Mean High Water Datum for Determination of Shoreline Position from Topographic Lidar Data: U.S. Geological Survey Open-File Report OFR 2005-1027, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

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

  1. How well have the observations been checked?
    The accuracy of this bathymetric change DEM is entirely dependent upon the accuracy of the two DEM surfaces (2008-2009 and 2016) used to calculate the elevation change it represents. DEM surfaces were created using a common snap raster to ensure direct pixel value comparison in quantifying bathymetric change. The accuracy of the 2008-2009 DEM is directly linked to the accuracy of the XYZ point data on which it is based (Dewitt and others, 2012). As reported (Dewitt and others, 2017) GPS base station, spaced approximately 15 to 20 km of the survey area, collected continuous data for GPS post-processing corrections. All static base station sessions were run through On-Line Positioning User Service (OPUS) resulting corrections produced +/-3.3 cm or less accuracy in the vertical component. The accuracy of the 2016 DEM is directly linked to the accuracy of the XYZ point data on which it is based (Dewitt and others, 2017). As reported (Dewitt and others, 2017) GPS base stations (spaced at 15-km from any roving vessel), collected continuous data for GPS post-processing corrections. All static base station sessions were run through the On-Line Positioning User Service (OPUS) and resulting corrections produced +/-0.023 m accuracy in the vertical component. Additionally, vertical datums associated with XYZ data have been recalculated (using VDatum and a NOAA tide gauge at Pensacola, FL) to allow for time series comparisons and this process introduces uncertainties into the data. Uncertainties are also introduced in interpolating DEM surfaces within Esri ArcGIS. The DEMs have not been independently verified for accuracy. For full accuracy and error information please see Dewitt and others (2012 and 2017), and metadata associated with each bathymetric DEM within this data release.
  2. How accurate are the geographic locations?
    The horizontal accuracy of this bathymetric change map is entirely linked to the accuracy of the DEMs used to create it (2008_2009_MS_NAD83NAVD88g12B_50m.tif and 2016_MS_NAD83NAVD88g12B_50m.tif). Dewitt and others (2012) report a horizontal accuracy value of +/- 10 to 13 cm for the orginal 2008-2009 bathymetric dataset used to create the 2008-2009 DEM. Dewitt and others (2017) report a horizontal accuracy value of +/- 0.013 m (maximum for latitude and longitude) for the original 2016 bathymetric dataset used to create the 2016 DEM. Additional sources of error include 1) vertical datum conversion using NOAA's Vdatum software and, 2) creation of a TIN and interpolation of the DEM raster, with 50-m cell size and using nearest neighbor interpolation, within ArcGIS (version 10.4.1).
  3. How accurate are the heights or depths?
    The vertical accuracy of this bathymetric change map is entirely linked to the accuracy of the 2008-2009 and 2016 DEMs (2008_2009_MS_NAD83NAVD88g12B_50m.zip and 2016_MS_NAD83NAVD88g12B_50m.zip). Dewitt and others (2012) report a vertical accuracy value of 3.3 cm for the original XYZ dataset used to create the 2008-2009 DEM. Dewitt and others (2017) report a vertical accuracy value of +/- 0.0992 m (0.023 m [OPUS] + 0.0762 m [Vdatum])for the 2016 XYZ bathymetric dataset used to create the 2016 DEM. Subsequent data processing steps, specifically converting vertical datum of the XYZ data and interpolating DEM surfaces within Esri ArcGIS, introduce additional sources of uncertainty that have not been fully assessed.
  4. Where are the gaps in the data? What is missing?
    The source data is historical and therefore not complete in its coverage. The source data was used to create DEM surfaces that best represent the historical soundings and were used to calculate bathymetric change, all while using best practice methods to keep the data as accurate as possible. See above accuracy report information for additonal details.
  5. How consistent are the relationships among the observations, including topology?
    This dataset includes the post-processed bathymetric data (XYZ) presented as an interpolated DEM representing bathymetric change occurring between July 2008 until 2016. The source data for the DEM was collected during multiple bathymetry surveys from 2008 to 2009 and 2016 near Ship, Horn, and Petit Bois in Mississippi. All spatial files provided in this data release are referenced in NAD83 UTM 16N (meters) and NAVD88 GEOID12B.

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:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Noreen A. Buster
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    nbuster@usgs.gov
  2. What's the catalog number I need to order this data set? 2016minus2008to2009_MS_NAD83NAVD88g12B_50m.tif
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), 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 constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data described or contained herein. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
Noreen A. Buster
U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
Geologist
600 4th Street South
St. Petersburg, FL
USA

(727) 502-8114 (voice)
nbuster@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/2016minus2008to2009_MS_NAD83NAVD88g12B_50m_metadata.faq.html>
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