Coastal Multibeam Bathymetry and Backscatter Data Collected in August 2024 From Breton Island, Louisiana

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Frequently anticipated questions:

What does this data set describe?

Title:
Coastal Multibeam Bathymetry and Backscatter Data Collected in August 2024 From Breton Island, Louisiana
Abstract:
An Ellipsoidally Referenced Survey (ERS) using two Teledyne Reson SeaBat T50-P multibeam echosounders, in dual-head configuration, was conducted by the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) covering the nearshore, Gulf side of Breton Island, Louisiana (LA), from August 6-9, 2024. This dataset, Breton_2024_MBES_xyz.zip, includes the processed elevation point data (x,y,z), as derived from a 1-meter (m) bathymetric grid. The download file, Breton_2024_MBES_Backscatter.zip, includes acoustic backscatter intensity data in 32-bit floating point GeoTIFF (Geographic Tagged Image File Format, .tif) format.
Supplemental_Information:
The processed sonar data are provided as American Standard Code for Information Interchange (ASCII) x,y,z point data files. These values are not the individual soundings, but nodes from a 1-m bathymetric grid. The Z value for the node is generated by utilizing a Combined Uncertainty and Bathymetry Estimator (CUBE) surface and has an estimated total value of uncertainty (Calder and Wells, 2007). The bathymetry data were collected and processed in the World Geodetic System of 1984 (WGS84) (G1150 realization) horizontal and vertical datums, and were subsequently transformed using the National Oceanic and Atmospheric Administration's (NOAA) VDatum version 4.7 (v.4.7) transformation software (https://vdatum.noaa.gov/) horizontally to the North American Datum of 1983 (NAD83 [2011]) and vertically to the North American Vertical Datum of 1988 (NAVD88) relative to the GEOID model of 2018 (GEOID18).
  1. How might this data set be cited?
    Bemelmans, Christopher C., Stalk, Chelsea A., and Flocks, James G., 20250402, Coastal Multibeam Bathymetry and Backscatter Data Collected in August 2024 From Breton Island, Louisiana:.

    This is part of the following larger work.

    Bemelmans, Christopher C., Stalk, Chelsea A., and Flocks, James G., 20250402, Coastal Multibeam Bathymetry and Backscatter Data Collected in August 2024 From Breton Island, Louisiana: U.S. Geological Survey data release doi:10.5066/P13BWAJC, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -89.20431444
    East_Bounding_Coordinate: -89.05087613
    North_Bounding_Coordinate: 29.4974589
    South_Bounding_Coordinate: 29.4324337
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 06-Aug-2024
    Ending_Date: 09-Aug-2024
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: tabular and 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 Point data set. It contains the following vector data types (SDTS terminology):
      • Point (15,303,492)
    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: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in meters
      The horizontal datum used is World Geodetic System of 1984.
      The ellipsoid used is WGS_84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: World Geodetic System of 1984
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    2024-320-FA_MBES_Breton_1m_WGS84_UTM16N.txt
    ASCII text (.txt) file containing the processed 1-m bathymetric grid x,y,z data in the WGS84 [G1150] realization (ellipsoid height). (Source: HYPACK®)
    WGS84_UTM16N_X
    WGS84 UTM Zone 16N X-coordinate (easting) of sample point, in meters. (Source: HYPACK®)
    Range of values
    Minimum:287728.000
    Maximum:296774.000
    Resolution:0.001
    WGS84_UTM16N_Y
    WGS84 UTM Zone 16N Y-coordinate (northing) of sample point, in meters. (Source: HYPACK®)
    Range of values
    Minimum:3263610.000
    Maximum:3258937.000
    Resolution:0.001
    WGS84_Z (m)
    WGS84 (ellipsoid height) of sample point, in meters. (Source: HYPACK®)
    Range of values
    Minimum:-39.776
    Maximum:-28.204
    Resolution:0.001
    TPU (m)
    TPU = Total Propagated Uncertainty, in meters. (Source: Teledyne CARIS™)
    Range of values
    Minimum:0.040
    Maximum:0.254
    Resolution:0.001
    2024-320-FA_MBES_Breton_1m_NAD83_UTM16N_NAVD88_G18.txt
    ASCII text (.txt) file containing the processed 1-m bathymetric grid x,y,z data in NAD83 [2011], NAVD88, which were derived using the GEOID18 model (orthometric height). (Source: VDatum)
    NAD83_UTM16N_X
    NAD83 UTM Zone 16N X-coordinate (easting) of sample point, in meters. (Source: VDatum)
    Range of values
    Minimum:287728.87000
    Maximum:296774.86700
    Resolution:0.00001
    NAD83_UTM16N_Y
    NAD83 UTM Zone 16N Y-coordinate (northing) of sample point, in meters. (Source: VDatum)
    Range of values
    Minimum:3258936.45000
    Maximum:3263609.44800
    Resolution:0.00001
    NAVD88_GEOID18_Z (m)
    NAVD88 (orthometric height) of sample point, in meters, with respect to GEOID12B. (Source: VDatum)
    Range of values
    Minimum:-14.072
    Maximum:-2.529
    Resolution:0.001
    TPU_WGS84 (m)
    Total Propagated Uncertainty, in meters, as reported for WGS84 (G1150) data. A static uncertainty value of 5.991 cm is associated with the transformation of this data. (Source: Teledyne CARIS™)
    Range of values
    Minimum:0.040
    Maximum:0.254
    Resolution:0.001
    Entity_and_Attribute_Overview:
    2024-320-FA_Breton_MBES_1m_Backscatter.tif: Dataset is a GeoTIFF included in the download file, Breton_2024_MBES_Backscatter.zip, which is acoustic backscatter intensity data in 32-bit floating point GeoTIFF (.tif) format with 14761 columns and 6940 rows. Dataset is projected to the WGS 1984 UTM Zone 16N coordinate system, with intensity values ranging from 21.327 to -37.204 dB.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Christopher C. Bemelmans
    • Chelsea A. Stalk
    • James G. Flocks
  2. Who also contributed to the data set?
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
  3. To whom should users address questions about the data?
    Christopher C. Bemelmans
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    Electronics Technician (Marine Instrumentation)
    600 4th Street South
    St. Petersburg, FL
    USA

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

Why was the data set created?

The purpose of the survey was to develop a digital elevation model of the seafloor environment around Breton Island for comparison with both previous and future elevation assessments, and to evaluate elevation change following island restoration. Data were collected during USGS Field Activity Number (FAN) 2024-320-FA. Seismic reflection data were acquired as a part of the same field activity, please see Forde and others (2025) for further details. Additional survey and data details are available from the USGS Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov/services/activity.php?fan=2024-320-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: 10-Aug-2024 (process 1 of 4)
    Acquisition: An ERS consisting of multibeam bathymetry was conducted using two Teledyne Reson SeaBat T50-P multibeam echosounders, in dual-head configuration. The pair of Mills Cross (configuration) transmit and receive arrays, were placed side-by-side within a bracket that oriented them at opposing 30-degree angles (relative to horizontal). The bracket was pole-mounted on the starboard gunnel of the research vessel (R/V) Sallenger, a 26-foot fiberglass vessel. The sonar arrays were oriented athwartships (primary and secondary arrays facing outward and down to port and starboard, respectively) and located approximately 1-m below the waterline when deployed. An Applanix Pos MV Wavemaster II V5 inertially aided navigation system was used for timing, positioning, and attitude. The Inertial Measurement Unit (IMU) was mounted atop the sonar bracket just aft of the pole. Two Trimble GA830 Global Navigation Satellite System (GNSS) antennas were affixed atop the cabin approximately amidships of the vessel, two meters apart, port-starboard. An AML Oceanographic Micro-X sound velocity sensor was used for speed of sound readings at the sonar head. A Sontek CastAway CTD was used for measuring sound velocity profiles. Hydrographic survey acquisition and processing software, HYPACK® and HYPACK HYSWEEP® (version 2023 Q3) managed data inputs from sensors and produced two files (.RAW and .HSX). Data were collected in WGS84 (G1150) Universal Transverse Mercator (UTM) Zone 16 North (16N) coordinates. Person who carried out this activity:
    Christopher C. Bemelmans
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cbemelmans@usgs.gov
    Date: 2024 (process 2 of 4)
    Processing: Positioning and attitude data were post-processed in POSPac software version 9.1 Service Pack 1. Raw position files were imported into POSPac and processed with the IN-Fusion PP-RTX processing mode utilizing Trimble CenterPoint RTX technology (Scherzinger and Hutton, 2025), creating smoothed best estimate of trajectory (SBET) files and dynamic error files (SMRMSG) for each day of the survey. Bathymetric data were post-processed in Teledyne CARIS™ Hydrographic processing software HIPS and SIPS version 11.4.28. HYPACK® acquisition files (.HSX) were first imported into CARIS™ and then post-processed navigation files (SBET and SMRMSG) were imported and applied (Caris, 2015). Additionally, Global Positioning System (GPS) tide (GPS tidal corrections utilize GPS height information from real time survey observations to obtain an ellipsoid height) was computed and sound velocity profiles were applied (IHO, 2019). Roll calibration was also performed, as necessary, and values were applied to the data. TPU was calculated from real time values recorded in the HSX and the SMRMSG files (IHO, 2019). Data were filtered to exclude any points with RESON Quality flags of 0, 1, and 2 (these flags are assigned to individual soundings at the time of acquisition and are a metric of pass/fail in regard to both brightness and collinearity: 0 = fail both, 1 = pass brightness only, 2 = pass collinearity only), as well as soundings that had a TPU greater than stated IHO Special Order standards (IHO, 2008). Refraction artifacts were addressed using Refraction Editor. Further editing was performed in Subset Editor. A 1-m bathymetric CUBE surface was computed and a visual and statistical inspection of the data effecting the surface was performed and edited as needed to serve as quality control (Calder and Wells, 2007). Gaps in the continuous surface were caused by limitations in swath width and planned line navigation within shallow waters. The final surface was exported as an x,y,z ASCII file using the 'Base Surface to ASCII' function. Person who carried out this activity:
    Christopher C. Bemelmans
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cbemelmans@usgs.gov
    Data sources produced in this process:
    • 2024-320-FA_MBES_Breton_ 1m_WGS84_UTM16N.txt
    Date: 2024 (process 3 of 4)
    Backscatter Mosaic Creation: Acoustic Intensity Backscatter data (.7k) were loaded in CARIS Hydrographic processing software HIPS/SIPS version 11.4.28 using the SIPS Backscatter tool. The final CUBE bathymetry surface serves as input for geometric corrections and average temperature and salinity data (derived from the Sontek CastAway CTD measurements taken during acquisition) are utilized by the program to calculate local absorption and transmission loss. These inputs, along with the following settings were entered into the tool, and then processing was initiated [Weighted Average = blending, image type = beam average, weighting = swath, and an Angle-Varying gain = 200]. During processing, the tool automatically creates a pattern file (.bbp) which is used to correct for variations in the beam pattern of the system. Upon completion, a 1-m backscatter mosaic with intensity values ranging from 21.327 to -37.204 dB (decibels) was created and the mosaic was exported as a 32-bit float GeoTIFF (.tif) using the 'surface to GeoTIFF' function. Person who carried out this activity:
    Christopher C. Bemelmans
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cbemelmans@usgs.gov
    Data sources produced in this process:
    • 2024-320-FA_Breton_MBES_1m_Backscatter.tif
    Date: 2024 (process 4 of 4)
    Datum Transformation: Final x,y,z data were converted using NOAA's VDatum v.4.7 software conversion tool from the WGS84 [G1150] realization to NAD83 [2011] NAVD88, using the GEOID18 model (orthometric height). Person who carried out this activity:
    Christopher C. Bemelmans
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cbemelmans@usgs.gov
    Data sources produced in this process:
    • 2024-320-FA_MBES_Breton_1m_NAD83_UTM16N_NAVD88_G18.txt
  3. What similar or related data should the user be aware of?
    International Hydrographic Organization (IHO), 20191031, The IHO-IOC GEBCO Cook Book: International Hydrographic Organization, Intergovernmental Oceanographic Commission, Monaco.

    Online Links:

    Other_Citation_Details: pages 81-83
    Caris, 20150601, CARIS HIPS and SIPS Training Manual: Caris, Fredericton, NB, Canada.

    Other_Citation_Details: pages 1-446
    Scherzinger, Dr. Bruno, and Hutton, Joe, 2025, Applanix IN-Fusion+™: the Ultimate Solution for Enhanced Spatial Intelligence: Trimble, Westminster, Colorado.

    Online Links:

    Other_Citation_Details: pages 1-9
    Calder, Brian R., and Wells, David E., 20070129, CUBE User's Manual: University of New Hampshire, Center for Coastal and Ocean Mapping, Durham, NH.

    Online Links:

    Other_Citation_Details: pages 1-54
    International Hydrographic Organization (IHO), 200802, IHO Standards for Hydrographic Surveys: International Hydrographic Bureau, 4, quai Antoine 1er B.P. 445 - MC 98011 MONACO Cedex Principaute de Monaco.

    Online Links:

    Other_Citation_Details: pages 1-28
    Forde, Arnell S., Stalk, Chelsea A., and Flocks, James G., 20250312, Chirp Sub-Bottom Profile Geophysical Data Collected in 2024 Offshore of Breton Island, Louisiana: U.S. Geological Survey data release doi:10.5066/P13SMFT7, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

    Online Links:

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

  1. How well have the observations been checked?
    This dataset was from a single research cruise with exact instrumentation and set up and were therefore internally consistent. Methods were employed to maintain data collection consistency aboard the platform. During mobilization, each piece of equipment was isolated to obtain internal and external offset measurements with respect to the survey platform. All the critical measurements were recorded manually and digitally entered into their respective programs.
  2. How accurate are the geographic locations?
    All data were collected and processed to meet or exceed International Hydrographic Organization (IHO) Special Order standards for positioning and depth (IHO, 2008). Individual Total Propagated Uncertainty (TPU) values associated with each node are available in the x,y,z file, with a mean value of 0.051 m.
  3. How accurate are the heights or depths?
    All data were collected and processed to meet or exceed IHO Special Order standards for positioning and depth (IHO, 2008). Individual TPU values associated with each node are available in the x,y,z file, with a mean value of 0.051 m. Data transformed using VDatum have an additional reported vertical transformation error of 5.991 centimeters (cm).
  4. Where are the gaps in the data? What is missing?
    These are complete, post-processed x,y,z bathymetric and backscatter data points from multibeam data collected nearshore Breton Island, Louisiana, August 2024.
  5. How consistent are the relationships among the observations, including topology?
    These files represent the post-processed bathymetric data (x,y,z) and acoustic intensity (.tif) during a multibeam bathymetry survey.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None. There are no access constraints associated with this data.
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)
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
    Attn: USGS SPCMSC Data Management
    600 4th Street South
    Saint Petersburg, FL
    United States

    727-502-8000 (voice)
    gs-g-spcmsc_data_inquiries@usgs.gov
  2. What's the catalog number I need to order this data set? 2024-320-FA_MBES_Breton_1m_WGS84_UTM16N.txt, 2024-320-FA_MBES_Breton_1m_NAD83_UTM16N_NAVD88_G18.txt, 2024-320-FA_Breton_MBES_1m_Backscatter.tif
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. 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: 02-Apr-2025
Metadata author:
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
Attn: USGS SPCMSC Data Management
600 4th Street South
Saint Petersburg, FL
United States

727-502-8000 (voice)
gs-g-spcmsc_data_inquiries@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/Breton_2024_MBES_Metadata.faq.html>
Generated by mp version 2.9.51 on Wed Apr 2 13:29:00 2025