Chenier_Plain_2017_SBB_200m_DEM_metadata: Nearshore Single-Beam Bathymetry XYZ Data Collected in 2017 from the Chenier Plain, Louisiana

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Frequently anticipated questions:

What does this data set describe?

Title:
Chenier_Plain_2017_SBB_200m_DEM_metadata: Nearshore Single-Beam Bathymetry XYZ Data Collected in 2017 from the Chenier Plain, Louisiana
Abstract:
As a part of the Barrier Island Comprehensive Monitoring Program (BICM), scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center conducted a nearshore single-beam bathymetry survey along the Chenier Plain, Louisiana from Marsh Island to Sabine Pass. The goal of the BICM program is to provide long-term data on Louisiana's coastline and use this data to plan, design, evaluate, and maintain current and future barrier island restoration projects. The data described in this metadata record will provide baseline bathymetric information for future research investigating island evolution, sediment transport, recent- and long-term geomorphic change and will support modeling of future changes in response to restoration and storm impacts. Over 3,300-line kilometers of single-beam data were acquired during two field missions: USGS Field Activity numbers (FAN) 2017-323-FA, conducted June 2-14, and 2017-324-FA, which occurred July 8-16, 2017 aboard four separate survey vessels. The final x,y,z data are provided in the native World Geodetic System of 1984 (WGS84) G1150 acquisition format (which is equivalent to the International Terrestrial Reference Frame of 2000 [ITRF00]), with values ranging from -26.62 m to -56.83m ellipsoid height, as well as the North American Datum of 1983 (NAD83) reference frame and the North American Vertical Datum of 1988 (NAVD88) GEOID12A , with values ranging from 0.00 to -30.13 m .
Supplemental_Information:
This record serves as a comprehensive archive for the final Digital Elevation Model (DEM) created using all single-beam bathymetry data collected under the FANs (2017-323-FA; 2017-324-FA), which encompass data from four separate survey platforms; research vessel (RV) Sallenger (17BIM01,17BIM05), RV Jabba Jaw (17BIM02, 17BIM06), RV Shark (17BIM03, 17BIM07), and RV Chum (17BIM04, 17BIM08). The single-beam bathymetry corrected positions were obtained through post processing of the base station data to the concurrent rover data. All datasets were transformed from their initial ITRF00 datum to NAD83 using the GEOID12A model (National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey (NGS) VDatum software 3.6 - http://vdatum.noaa.gov/). The final x,y,z position point data were gridded at a 200-meter cell size resolution to create the digital elevation models, which represent elevations from -26.66 to -56.83 meters ITRF00 and 0 to -30.13 meters NAVD88 GEOID12A.
  1. How might this data set be cited?
    Stalk, Chelsea A., Flocks, James G., Bernier, Julie C., DeWitt, Nancy T., Fredericks, Jake J., Kelso, Kyle W., Farmer, Andrew S., Tuten, Thomas M., and Wilcox, Hunter S., 20180628, Chenier_Plain_2017_SBB_200m_DEM_metadata: Nearshore Single-Beam Bathymetry XYZ Data Collected in 2017 from the Chenier Plain, Louisiana: U.S. Geological Survey Data Release doi:10.5066/F7CV4GZH, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -93.8409
    East_Bounding_Coordinate: -91.7451
    North_Bounding_Coordinate: 29.7772
    South_Bounding_Coordinate: 29.4338
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 02-Jun-2017
    Ending_Date: 16-Jul-2017
    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 187 x 1013 x 1, 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: 15
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -93
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 200
      Ordinates (y-coordinates) are specified to the nearest 200
      Planar coordinates are specified in meters
      The horizontal datum used is WGS84 (G1150), NAD83.
      The ellipsoid used is WGS84, Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: NAVD88 GEOID12A
      Depth_Resolution: 0.10
      Depth_Distance_Units: meter
      Depth_Encoding_Method: Implicit coordinate
  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)
    • Chelsea A. Stalk
    • James G. Flocks
    • Julie C. Bernier
    • Nancy T. DeWitt
    • Jake J. Fredericks
    • Kyle W. Kelso
    • Andrew S. Farmer
    • Thomas M. Tuten
    • Hunter S. Wilcox
  2. Who also contributed to the data set?
    U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center (SPCMSC)
  3. To whom should users address questions about the data?
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher I
    600 4th Street South
    St. Petersburg, FL
    USA

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

Why was the data set created?

These 200-meter cell size digital elevation models are an interpretive product that was derived from the processed single-beam bathymetry data collected in June and July 2017 along the Chenier Plain, Louisiana. Additional survey details are available at https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-323-FA and https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-324-FA.

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: 2017 (process 1 of 6)
    DGPS Navigation Processing: A total of 8 Geographic Positioning Systems (GPS) base stations were established throughout the survey area, 5 of which were located on NGS established marks, 1 on a USGS installed mark, and 2 on other marks within the Rockefeller National Wildlife Refuge. Located in the eastern portion of the survey area, NGS mark DN4165 is established at the mouth of the freshwater lock to the west of Marsh Island. USGS established mark MIGP, installed in 2016, is located on the western shore of Marsh Island. Near the middle of the survey area, RFS1 (markings Fish Lab 1), and ME18 were located on the grounds of the Rockefeller National Wildlife Refuge. In the western portion of the survey area, NGS mark DJ9378 is established near the northern grass edge of the boat ramp at the southern end of Calcasieu Pass, this mark was found damaged with a bent rod tip. Because of the damage, coordinates derived from survey occupations were used in final processing. NGS mark DH3817 is located off Highway 27 in Cameron city limits and mark AV0360 is in Holly Beach on the grounds of the torn down church, near the stop sign. The most western NGS mark utilized is DN4168, which is located off Highway 82 past the high school near the Sabine Pass Bridge. All base stations were occupied 24 hours and equipped with Ashtech Proflex GPS receivers recording 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via Thales Choke-ring antennas, recording at a rate of 0.1 seconds (s). The coordinate values for each of the GPS base stations are the time-weighted average of values obtained from the NGS?s OPUS. All base station sessions of recorded data are decimated to 30-seconds (s), and then submitted to OPUS via the online service. All solutions are then returned to the user and entered into a spreadsheet where time-weighted ellipsoid values are calculated for each station, for the entire occupation. Any individual ellipsoid value that falls outside three standard deviations for the entire occupation was excluded and the final coordinate values were then determined. The final base station coordinates were imported into GrafNav version 8.7 (Waypoint Product Group) and the kinematic GPS data from the survey vessel were post-processed to the concurrent GPS data from the base stations. During processing, steps were taken to ensure that the trajectories between the base and rover were clean and resulted in fixed positions. By analyzing the graphs, trajectory maps, and processing logs that GrafNav produces for each GPS session, GPS data from satellites flagged by the program as having poor health or satellite time segments with cycle slips were excluded, and the satellite elevation mask angle was adjusted to improve the position solutions, when necessary. The final, differentially corrected, precise DGPS positions were computed and then exported in ASCII text format. The file was then used to replace the uncorrected real-time rover positions recorded during acquisition. The GPS data were processed and exported in the World Geodetic System of 1984 (WGS84) (G1150) geodetic datum UTM zone 15N. Person who carried out this activity:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher I
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Date: 2017 (process 2 of 6)
    Single-Beam Processing: All data were processed using CARIS HIPS and SIPS (Hydrographic Information Processing System and Sonar Information Processing System) version 10.2.1. The raw HYPACK data files were imported into CARIS, the differentially corrected navigation files were imported using the generic data parser tool within CARIS, and any SVP profile casts were entered and edited using the SVP editor. The bathymetric data components (position, motion, depth, and SOS) were then merged and geometrically corrected in CARIS to produce processed x,y,z data. Next, the data were edited for outliers and then further reviewed in the Subset Editor utility for crossing status, and questionable data points or areas were additionally reviewed. The geometrically corrected point data were then exported as an x,y,z ASCII text file referenced to WGS84 (G1150), equivalent to ITRF00, Universal Transverse Mercator (UTM) 15, and ellipsoid height in meters. The combined single-beam bathymetry dataset consists of 14,345,969 x,y,z data points with an ellipsoidal height range of -56.83 m to -26.62 m. Person who carried out this activity:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher I
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Data sources produced in this process:
    • 17BIM01_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM02_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM03_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM04_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM05_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM06_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM07_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM08_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt
    Date: 2017 (process 3 of 6)
    Quality Control and Quality Assurance (QA/QC): All single-beam data exported from CARIS were imported into Esri ArcMap version 10.3.1, where a shapefile of the individual data points (x,y,z) was created and plotted in 0.5-m color coded intervals. First, all data were visually scanned for any obvious outliers or problems. Next, a Python script was used to evaluate elevation differences at the intersection of crossing tracklines by calculating the elevation difference between points at each intersection using an inverse distance weighting equation. GPS cycle slips, stormy weather conditions, and rough sea surface states can contribute to poor data quality. In all cases where discrepancies in the data, or high (>0.30 m) crossing values were found, there was sufficient data coverage to delete the problem data points and/or lines. The script was run on all vessel point data first on a vessel by vessel basis and then run a final time for all data points from all vessels collectively within a merged file. A total of 4,406 crossing values were observed throughout the survey area, 95% of which are less than 0.30m. Once the dataset passed all QA/QC procedures and manual editing steps, the data were considered final and included in the download section of this data release. Person who carried out this activity:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher I
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Data sources used in this process:
    • 17BIM01_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM02_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM03_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM04_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM05_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM06_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM07_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt 17BIM08_SBB_Level_03_xxx_WGS84_ITRF00_UTM15N.txt
    Data sources produced in this process:
    • Chenier_Plain_2017_SBB_Level_03B_xxx_ITRF00.txt
    Date: 2017 (process 4 of 6)
    Datum Transformation: The text file, Chenier_Plain_2017_SBB_Level_03B_xxx_ITRF00.txt, was converted using NOAA?s VDatum software conversion tool version 3.6 (reported vertical transformation error is 7.6158 cm) from ITRF00 to the NAD83 reference frame and NAVD88 orthometric height using the National Geodetic Survey (NGS) geoid model of 2012A (GEOID12A). Person who carried out this activity:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher I
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Data sources used in this process:
    • Chenier_Plain_2017_SBB_Level_03B_xxx_ITRF00.txt
    Data sources produced in this process:
    • Chenier_Plain_2017_SBB_Level_03B_xxx_NAD83_NAVD88_G12A.txt
    Date: 2015 (process 5 of 6)
    Gridding bathymetric data and computing grid error: The single-beam soundings were imported into Esri's ArcMap version 10.3.1 and gridded using Spatial Analyst tools "create TIN," "TIN to raster," and "extract by raster mask." First a bounding polygon representing the extent of survey tracklines was created and converted into a raster mask using the ArcGIS "polygon to raster" tool. Next, the final point data were constructed into a triangulated irregular network (TIN) using the "create TIN" tool and then the data were converted into a raster DEM by utilizing the "TIN to raster? tool and natural neighbor function with a cell size of 200 m. Finally, the interpolated DEM is clipped to the survey extent by use of the "extract by mask" tool and applying the raster mask created first in this process. The final product is a DEM of the entire survey extent. The grid range values were from -26.66 m to -68.94 m for the ITRF00 ellipsoid DEM and 0.00 m to -30.13 m for the NAVD88 GEOID12A DEM. In order to evaluate how well the final DEM represents the final sounding data both spatially and quantitatively, a comparison of the DEM versus the x,y,z point data was plotted in ArcGIS by use of the "Extract values by points" spatial analyst tool. This tool extracts the value represented by the underlying grid and compares it to that of the overlying point data. By use of the generated shape file and associated attribute table, the root mean square (RMS) error, quantified as the difference between the measured depth and the grid depth values, was calculated. Almost 97% of the point data are represented by the DEM and has an overall RMS of 0.51 m. It is known that gridding algorithms, by nature, do not account well for steep slopes or channel coverage, and when present, usually unnecessarily increase the RMS error value for the entire dataset. To better represent the actual RMS error on the continental shelf, known dredged channels were removed from the. The extraction process and RMS calculation were then repeated resulting in 90% point data utilization with an overall RMS error of 0.19 m. Person who carried out this activity:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher I
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Data sources used in this process:
    • Chenier_Plain_2017_SBB_Level_03B_xxx_ITRF00.txt, Chenier_Plain_2017_SBB_Level_03B_xxx_NAD83_NAVD88_G12A.txt
    Data sources produced in this process:
    • Chenier_Plain_2017_SBB_ITRF00_200_DEM.tif, Chenier_Plain_2017_SBB_NAD83_NAVD88_GEOID12A_200_DEM.tif
    Date: 13-Oct-2020 (process 6 of 6)
    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?

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

  1. How well have the observations been checked?
    The accuracy of the data is determined during data collection. Methods are employed to maintain data collection consistency aboard all survey platforms. During mobilization, each piece of equipment is isolated to obtain internal and external offset measurements with respect to the survey platform. Offsets between the single-beam transducers and the Ashtech antenna reference point (ARP) were measured and accounted for in post-processing. Differential Global Positioning System (DGPS) coordinates were obtained using post-processing software packages (National Geodetic Survey On-Line Positioning User Service, OPUS, and Waypoint Product Group GrafNav, version 8.7.
  2. How accurate are the geographic locations?
    All static base station sessions were processed through OPUS maintained by NOAA and the NGS. The OPUS solutions were entered into a spreadsheet to compute a final, time-weighted position (latitude, longitude, and ellipsoid height) for each base station. The time-weighted positions for all base stations occupying established NGS benchmarks (DN4165, DH3817, DN4168, AV0360, and DJ9378) were compared against the published NGS coordinates. The time-weighted positions at base stations DN4165, DH3817, and DN4168 were within 3 standard deviations of the published positions for each NGS mark (DN4165: +/-0.31 cm North, +/-0.27 cm East; DH3817: +/-0.66 cm North, +/-0.57 cm East; and DN4168: +/-0.29 cm North +/-0.25 cm East), and the published positions for those base stations were used in subsequent processing steps. The time-weighted positions at base stations AV0360 and DJ9378, however, varied by more than 3 standard deviations from the published coordinates. At these base stations, the time-weighted average coordinates computed from the survey occupations were used. The horizontal variability of the base station coordinates at AV0360 and DJ9378 as well as UGSG-installed mark MIGP, and other marks ME18, and RFS1, were determined by calculating the maximum difference of any individual occupation from the time-weighted average latitude and longitude values (MIGP: 0.00030 seconds latitude, 0.00021 seconds longitude; ME18: 0.00022 seconds latitude, 0.00014 seconds longitude; RFS1: 0.00036 seconds latitude, 0.00035 seconds longitude; AV0360: 0.0022 seconds latitude, 0.00044 seconds longitude; and DJ9378: 0.0029 seconds latitude, 0.00018 seconds longitude). Continuously Operating Reference Station (CORS) station TXPT data were also utilized, reported horizontal error equals +/-1.2 cm east and north.
  3. How accurate are the heights or depths?
    All static base station sessions were processed through OPUS, which is maintained by NOAA and the NGS. The OPUS solutions were entered into a spreadsheet to compute a final, time-weighted position (latitude, longitude, and ellipsoid height) for each base station. The time-weighted positions for all base stations occupying established NGS marks (DN4165, DH3817, DN4168, AV0360, and DJ9378) were compared against the published NGS coordinates. The time-weighted positions at base stations DN4165, DH3817, and DN4168 were within 3 standard deviations of the published positions for each NGS mark (DN4165: +/-0.97 cm; DH3817: +/-2.80 cm; and DN4168: +/-0.98 cm), and the published positions for those base stations were used in subsequent processing steps. The time-weighted positions at base stations AV0360 and DJ9378, however, varied by more than 3 standard deviations from the published coordinates. At these base stations, the time-weighted average coordinates computed from the survey occupations were used. The vertical variability of the base station coordinates at AV0360 and DJ9378 as well as UGSG-installed mark MIGP, and other marks ME18, and RFS1, were determined by calculating the maximum difference of any individual occupation from the time-weighted average ellipsoid height values (MIGP: +/-2 cm; ME18: +/-3.2 cm; RFS1: +/-2.7 cm; AV0360: +/-1.4 cm; and DJ9378: +/-1.4 cm). CORS station TXPT data were also utilized, reported vertical error equals +/- 0.4 cm ellipsoid height.
  4. Where are the gaps in the data? What is missing?
    This dataset is considered complete for the information presented, as described in the abstract section. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    These datasets are from two field activities with consistent instrument calibrations. The DEM is a 200-meter cell size interpolated grid; data gaps between acquisition tracklines are predicted values generated by the gridding algorithm - Natural Neighbors.

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)
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher I
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
  2. What's the catalog number I need to order this data set? Chenier_Plain_2017_SBB_ITRF00_200m_DEM.tif, Chenier_Plain_2017_SBB_NAD83_NAVD88_GEOID12A_200m_DEM.zip
  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, 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?
  5. What hardware or software do I need in order to use the data set?
    The raster contained in the .zip file is available as GeoTIFF. To utilize this data, the user must have a GIS software package capable of reading .tif format.

Who wrote the metadata?

Dates:
Last modified: 02-Nov-2023
Metadata author:
Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Attn: Chelsea A Stalk
Researcher I
600 4th Street South
St. Petersburg, FL
USA

727-502-8000 (voice)
cstalk@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/Chenier_Plain_2017_SBB_200m_DEM_metadata.faq.html>
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