Single-Beam Bathymetry Data Collected in 2022 from Point Aux Chenes Bay, Mississippi

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   DeWitt, Nancy T., 20240708, Single-Beam Bathymetry Data Collected in 2022 from Point Aux Chenes Bay, Mississippi:.

   This is part of the following larger work.
   DeWitt, Nancy T., Galbraith, Ben A., Terrano, Joseph F., Smith, Christopher G., Smith, Kathryn E.L., and Stalk, Chelsea A., 20240708, Single-Beam Bathymetry Data Collected in 2022 from Point Aux Chenes Bay, Mississippi: U.S. Geological Survey data release doi:10.5066/P13NPYMZ, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

   Online Links:

   • https://doi.org/10.5066/P13NPYMZ

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -88.493101
   East_Bounding_Coordinate: -88.370431
   North_Bounding_Coordinate: 30.360461
   South_Bounding_Coordinate: 30.295028
   

3. What does it look like?
4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 10-Jun-2022

   Ending_Date: 08-Nov-2022

   Currentness_Reference:

   ground condition

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: tabular, vector, 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 (2553419)
   2. What coordinate system is used to represent geographic features?
      

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:

      UTM_Zone_Number: 16N
      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 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_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      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: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
      

7. How does the data set describe geographic features?

   Point_Aux_Chenes_2022_Coverage.shp

   Polygon shapefile (.shp) of the coverage area at Point Aux Chenes, MS. Data is projected to the NAD83 UTM 16N coordinate system and is included in the Point_Aux_Chenes_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.zip download file. (Source: U.S. Geological Survey)

   FID

   Internal feature number (Source: Esri) Sequential unique whole numbers that are automatically generated.

   Shape*

   Feature geometry. (Source: Esri) Coordinates defining the features.

   Shape_Leng

   Length of the polygon coverage, in meters (Source: Esri)

   Range of values
   Minimum:	40437.9381034
   Maximum:	40437.9381034

   Shape_Area

   Area of the polygon coverage, in meters (Source: Esri)

   Range of values
   Minimum:	31191864.572
   Maximum:	31191864.572

   Point_Aux_Chenes_2022_Shoreline_Points.shp, Point_Aux_Chenes_2022_Shoreline_Polyline.shp

   Point and polyline shapefiles (.shp) alongshore at Point Aux Chenes, MS. Data is projected to the NAD83 UTM 16N coordinate system and is included in the Point_Aux_Chenes_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.zip download file. (Source: U.S. Geological Survey)

   FID

   Internal feature number (Source: Esri) Sequential unique whole numbers that are automatically generated.

   Shape*

   Feature geometry. (Source: Esri) Coordinates defining the features.

   Date_

   Date and time of data point using the "MM/DD/YYYY HH:MM:SS" format. Date imagery or shoreline was collected using the "MM/DD/YYYY HH:MM:SS" format. The HH:MM:SS was set at 3:00:00 PM for all shorelines as a general placeholder. (Source: U.S. Geological Survey)

   Range of values
   Minimum:	05/11/2022 3:00:00 PM
   Maximum:	05/11/2022 3:00:00 PM

   Year

   4-digit year (YYYY) in which the imagery was collected. (Source: Esri)

   Range of values
   Minimum:	2022
   Maximum:	2022
   Units:	Year

   Accuracy

   A value representing the shoreline position uncertainty associated with the imagery type. (Source: U.S. Geological Survey)

   Range of values
   Minimum:	0.0
   Maximum:	3.2
   Units:	meters

   Orig_Name

   The original name of the downloaded file. (Source: U.S. Geological Survey) A text string describing the name of the file as it was downloaded from the original source or created by the USGS.

   Source

   An identifier for the source of the vector shoreline data. (Source: U.S. Geological Survey)

   Value	Definition
   USGS	Data collected or digitized by the USGS Coastal and Marine Science Center- St. Petersburg, FL.

   Download

   A text string describing the web address for the original of the shoreline. (Source: U.S. Geological Survey) https://doi.org/10.5066/P13NPYMZ

   Notes

   Any data documentation notes. (Source: U.S. Geological Survey) A text string describing the notation.

   Entity_and_Attribute_Overview:

   Point_Aux_Chenes_2022_SBES_xyz.zip: Comma-delimited ASCII text files (.txt) containing the processed single-beam bathymetry data points of Point Aux Chenes, MS, from USGS FAN 2022-320-FA in June and November 2022. The detailed attribute descriptions for this file are included in an accompanying data dictionary (Data_Dictionary_single-beam_bathymetry_measurements.docx). These metadata are not complete without this file. The order of the single-beam attribute columns may vary between data files and the order listed in the data dictionary. Users are advised to carefully review the attribute column order in each data file when viewing or using the data.

   Entity_and_Attribute_Overview:

   Point_Aux_Chenes_2022_SBES_tracklines.zip: Polyline shapefiles (.shp) of the single-beam bathymetry tracklines of Point Aux Chenes, MS, from USGS FAN 2022-320-FA in June and November 2022. The detailed attribute descriptions for this file are included in an accompanying data dictionary (Data_Dictionary_single-beam_bathymetry_measurements.docx). These metadata are not complete without this file.

   Entity_and_Attribute_Overview:

   Point_Aux_Chenes_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.tif: 10-m cell size gridded DEM (.tif) of Point Aux Chenes, MS, from USGS FAN 2022-320-FA in June 2022. The ellipsoid elevation ranges from 0 m to -4.18 m and is projected to the NAD83 UTM 16N coordinate system. The file format is a 32-bit floating point GeoTIFF with 1171 columns and 721 rows.

   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)
   • Nancy T. DeWitt
2. Who also contributed to the data set?
   Efforts were supported by the Estuarine and MaRsh Geology project (EMRG) and the National Oceanic and Atmospheric Association (NOAA) Effects of Sea Level Rise (ESLR) Program in partnership with Grand Bay National Estuarine Research Reserve and Mississippi State University.
   Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. WorldView 2 imagery was accessed through a special use agreement with Maxar Technologies (Maxar Technologies, 2022).
3. To whom should users address questions about the data?
   Nancy T. DeWitt

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ndewitt@usgs.gov

Why was the data set created?

How was the data set created?

1. From what previous works were the data drawn?

   WorldView 2 imagery (source 1 of 1)

   Technologies, Maxar, 2022, Global Enhanced GEOINT Delivery (G-EGD): Maxar Technologies (formerly DigitalGlobe Inc.), Westminster, CO.

   Online Links:

   • https://evwhs.digitalglobe.com/

   Type_of_Source_Media: raster image
   Source_Contribution:

   High resolution satellite imagery collected in 2022 used to derive shorelines in the Point Aux Chenes study area.

2. How were the data generated, processed, and modified?

   Date: 08-Nov-2022 (process 1 of 9)

   GNSS Data Acquisition: Two Global Navigational Satellite Systems (GNSS) base stations were established on NGS benchmarks in which the roving vessels would be within 10-15 kilometers (km) of the base station at any given time. The primary benchmark B166 was located to the north-east of the survey extent at the entrance to Bayou Heron Boat Ramp. The secondary base station NER1 was also located to the north-east on the Grand Bay National Estuarine Research Reserve. The base stations were equipped with Spectra Precision SP90M GNSS receivers recording full-carrier-phase positioning signals from satellites via a Trimble Zephyr 3 Base GNSS antennas recording at a rate of 0.1 second (s). The roving vessels were each outfitted with Spectra Geospatial SP90M GNSS receivers and GNSS antennae recording data at the same rate. The GNSS data files were converted from Spectra Precision proprietary G-file formats (for example, GB166A22.158, GWVR1A22.158, GWVR2A22.158) into the non-proprietary RINEX raw data file format (version 2.11) using the RINEX Converter program. The base and rover RINEX files were post processed together in a subsequent step to obtain differentially corrected navigation data and is described later in the metadata. Example RINEX filename WVR11580.22O, where 'WVR1' is the four-letter site name, '158' is the day of year, '0' is the session 0-#, '17' is the year, 'O' is the observation file, 'N' is the navigation file, 'M' is meteor logical file, and 'G' is the GLONASS navigation message file. The GNSS data acquisition was completed for both survey months (June and November) using identical equipment. Person who carried out this activity:
   

   Nancy T. DeWitt

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ndewitt@usgs.gov

   Data sources produced in this process:

   • WVR11580.22O, WVR11580.22N, WVR11580.22M

   Date: 2023 (process 2 of 9)

   Single-Beam Bathymetry Acquisition: The single-beam bathymetric data collected under the USGS FAN 2022-320-FA, include two separate survey platforms/subFANs. The first survey occurred in June 2022, collected by the R/V SHARK (WVR1 - subFAN 22CCT09), and the R/V CHUM (WVR2 - subFAN 22CCT10), both 12-ft Yamaha personal watercraft (PWC) which collected 242.44 line-km and 216.39 line-km, respectively. In November 2022, WVR1 (subFAN 22CCT11) collected 68 line-km (20 lines) and the WVR2 (subFAN 22CCT12) collected 68 line-km. Boat motion was recorded at 50-millisecond (ms) using a SBG Ellipse A motion sensor. HYPACK A Xylem Brand (version 21.0.2.0, only subFAN 22CCT09 used version 21.3.1.0), a marine surveying, positioning, and navigation software package, managed the planned-transect information and provided real-time navigation, steering, correction, data quality, and instrumentation-status to the boat operator. Depth soundings were recorded at 50-ms intervals using an Odom echotrac CV100 echosounder with a 4-degree, 200-kilohertz (kHz) transducer. Data from the GNSS receiver, motion sensor, and echosounder were recorded in real-time aboard all vessels independently and merged into a single raw data file (.RAW) in HYPACK, with each device string referenced by a device identification code and time stamped to Coordinated Universal Time (UTC).
   Sound velocity profile (SVP) measurements were collected using SonTek Castaway Conductivity, Temperature, and Depth (CTD) instruments. The instruments were periodically cast overboard to record changes in water column speed of sound (SOS). In the June 2022 survey, 78 successful sound velocity casts were collected and ranged in depth from 0.15 to 3.79 m (average 3.70 m), and in sound velocity from 1522.17 to 1544.71 meters per second (m/s) (average 1532.73 m/s). In the November 2022 survey, 9 successful sound velocity casts were collected and ranged in depth from 0.15 to 2.21 m (average 0.77 m), and in sound velocity from 1524.21 to 1524.36 m/s (average 1523.03 m/s) Person who carried out this activity:
   

   Nancy T. DeWitt

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ndewitt@usgs.gov

   Data sources produced in this process:

   • *.RAW, *.BIN, *.LOG,*.ctdx, *.ctd, *.csv, *.svp

   Date: 2023 (process 3 of 9)

   Differentially Corrected Navigation Processing : The NGS Permanent Identifier (PID) DO5987, stamping 0166 B 2010 (https://www.ngs.noaa.gov/OPUS/getDatasheet.jsp?PID=DO5987), was the primary base station location for this dataset. For this dataset remain consistent with the 2015 and 2021 bathymetry datasets (DeWitt and others, 2017; Stalk and others, 2021), the same base location (DO5987) and base value were used for data collection and post-processing. However, to be current with the WGS84 (G2139) realization during acquisition, the base position used to post-process navigation data during the 2015 survey (DeWitt and others, 2017) was converted from ITRF2008 (equivalent to WGS84) into WGS84 (G2139) using the Horizontal Time-Dependent Positioning (HTDP) online transformation utility. The latest realization (G2139) was introduced on 01/23/2021. The survey acquisition dates succeed this date; therefore, it is the appropriate datum realization for post-processing the navigation data. The resultant base position used for post-processing was 30°24’46.75374 North, 88°24’12.11420 West (WGS84-G2139), and -29.032 meters (m) ellipsoid height (WGS84-G2139). A secondary base station was erected on PID DP1533, stamping 5 T 2 2013, but it was not needed for post-processing. The kinematic trajectories (rover to base) were processed using Novatel’s Waypoint GrafNav software.
   The rover RINEX and the base RINEX files were imported into GrafNav, converted into proprietary files, and the kinematic (rover) GNSS data session from the survey vessel was post-processed to the concurrent base GNSS data session. Analyzing the data plots, trajectory maps, processing logs, satellite health plots, and other viewing utilities that GrafNav produces, provided measures to attain trajectory solutions (between the rover and the base) free of erroneous data that resulted in fixed positions. Some analytic examples include 1) excluding satellites flagged by the program as having bad/poor health or cycle slips, 2) Excluding poor satellite time segments that have a negative influence toward a fixed solution, and 3) adjusting the satellite elevation mask angle to improve the position solutions. This process was repeated for every GNSS data session. The final differentially corrected, precise DGPS positions were computed at 0.1 s and exported in American Standard Code for Information Interchange (ASCII) text format (.txt) in WGS84 (G2139) UTM 16N geodetic datum. One text file is produced for each roving GNSS session using the example file naming convention: 22CCT09_158_2022_B166_TWVR1_A.txt where the convention '22CCT09' is the subFAN, '158' is day of year, '2022' is the year, 'B166' is the base station used, 'WVR1' is the rover, and 'A' is the GPS session from A to Z.
   During the November survey on WVR2 (22CCT12), the GNSS unit stopped recording internally so that data was not available to post-process from the rover to the base station. GPS was recorded to the HYPACK .RAW files, but only as Satellite Based Augmentation System (SBAS) which does not produce centimeter accuracy. The lines affected were not included in this data release. Please refer to the Quality Control, Quality Assurance (QA/QC) and Uncertainty Analysis process steps in this metadata record for more information. Person who carried out this activity:
   

   Nancy T. DeWitt

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ndewitt@usgs.gov

   Data sources used in this process:

   • *.22O, *.22N, *.22G, *.22M

   Date: 2023 (process 4 of 9)

   Bathymetry Processing: All data were processed using CARIS HIPS and SIPS version 11.4.14. First, a vessel file *.vhf unique to the platform, was created that contains the surveyed offset measurements between the sensors. A CARIS project was created using the *.vhf file, and then the HYPACK *.RAW and the SVP profiles *.SVP were loaded. Next, the differentially corrected navigation files were imported using the generic data parser tool. Then, the differently corrected navigation files overwrote every non-differential position in the HYPACK *.RAW file based upon time. The bathymetric data components (position, motion, depth, and SOS) were then georeferenced and geometrically corrected in CARIS to produce processed xyz positional data. The data points were further analyzed using CARIS single-beam editor and subset editor tools providing 2-dimensional (2D) and 3-dimensional (3D) data views respectively. At this point, these tools help highlight any remaining echosounder artifacts or issues commonly associated with shallow water single beam surveys. Some examples include the following 1.) erroneous or false values, 2) patchy, inconsistent depth soundings usually a result of a vessels limitations in extremely shallow water, 3) the seafloor sediment composition can absorb or deflect sound, 4) the transducer measurement threshold, and 5) instrument malfunction. Outlier data was either filtered out or manually removed. Any questionable areas were assessed for repair against their surrounding data and ultimately removed from the dataset if a solution was not found. Once editing was considered complete, the point data were then exported as an xyz ASCII text file referenced to WGS84 (G2139) UTM 16N (DeWitt and others, 2017; Hansen and others, 2017). Person who carried out this activity:
   

   Nancy T. DeWitt

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ndewitt@usgs.gov

   Data sources used in this process:

   • *.vhf, *.RAW, *.svp, *.txt

   Data sources produced in this process:

   • 22CCT09_WVR1_SBES_WGS84_UTM16N_Level003_xyz.txt
   • 22CCT10_WVR2_SBES_WGS84_UTM16N_Level003_xyz.txt
   • 22CCT11_WVR1_SBES_WGS84_UTM16N_Level003_xyz.txt
   • 22CCT12_WVR2_SBES_WGS84_UTM16N_Level003_xyz.txt

   Date: 2023 (process 5 of 9)

   Quality Control, Quality Assurance (QA/QC) and Uncertainty Analysis: The single-beam data exported from CARIS HIPS and SIPS (two vessel/subFAN xyz ASCII text files for both surveys) were transformed in ArcMap to a point shapefile (.shp) utilizing the "Create Feature Class From XY Table" geoprocessing tool. The projection was set to WGS84 UTM 16N. The generated shapefile was visually scanned for any obvious outliers or problems. Next, a polyline shapefile (representing tracklines) was produced from the point shapefile using XTools Pro "Make Polylines from Points" geoprocessing tool for each survey platform (subFANs 22CCT09, 22CCT10, 22CCT11 and 22CCT12). Utilizing both the xyz (point) and trackline (polyline) shapefiles, 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 with a search radius of 3 m (DeWitt and others, 2017; Hansen and others, 2017). After each vessel was reviewed individually and initial crossing values assessed, the shapefiles were merged by geographic area and time. June subFANs 22CCT09 and 22CCT10 were merged to create the following point shapefiles: Point_Aux_Chenes_June_2022_SBES_WGS84_UTM16N_xyz.shp, Point_Aux_Chenes_North_Reef_June_2022_SBES_WGS84_UTM16N_xyz.shp, and Point_Aux_Chenes_South_Reef_June_2022_SBES_WGS84_UTM16N_xyz.shp. November subFANs 22CCT11 and 22CCT12 data were merged together to create Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_xyz.shp, Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_xyz.shp, and Point_Aux_Chenes_South_Reef_November_2022_SBES_WGS84_UTM16N_xyz_pp.shp. These point shapefiles are intermediate datasets (not published in this release) used to produce the trackline shapefiles. These point shapefiles were later re-converted to an ASCII text file (.txt) for inclusion in this data release, refer to the additional process steps below for more information. The trackline shapefiles were produced from these point shapefiles as previously described, and the Python script was applied again an inverse distance weighting equation with a search radius of 3 m.
   The maximum crossing error for Point_Aux_Chenes_June_2022_SBES_WGS84_UTM16N_xyz.shp was 28 cm between the WVR1 and WVR2 files. The final crossing file had 1847 crossings with a range of 0.00 to 28 cm and standard deviation 0.05 cm, in which 72.00% were 10 cm or less; 26.08% were between 10-20 cm; 1.92% were between 20-30 cm.
   The maximum crossing error for Point_Aux_Chenes_North_Reef_June_2022_SBES_WGS84_UTM16N_xyz.shp was 16 cm between the WVR1 and WVR2 files. The final crossing file had 399 crossings with a range of 0.00 to 16 cm and standard deviation 0.04 cm, in which 94.74% were 10 cm or less; 5.26% were between 10-20 cm. Two tracklines could not be merged with the corresponding differential navigation data during post-processing due to a processing bug. This resulted in an offset from the surrounding lines. To correct the data, the ellipsoid value of the line was adjusted by the average value of all the crossings that went through that particular line. Line 22CCT09_174_0031_1700 was adjusted by -0.24 m and 22CCT09_174_0032_1702 by -0.41 m. This adjustment is represented in the Point_Aux_Chenes_June_2022_SBES_WGS84_UTM16N_xyz.txt file as well.
   The maximum crossing error for Point_Aux_Chenes_South_Reef_June_2022_SBES_WGS84_UTM16N_xyz.shp was 17 cm between the WVR1 and WVR2 files. The final crossing file had 316 crossings with a range of 0.00 to 17 cm and standard deviation 0.02 cm in which 99.05% were 10 cm or less; 26.38% were between 10-20 cm.
   The maximum crossing error for Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_xyz.shp was 28 cm between the WVR1 and WVR2 files. The final crossing file had 1847 crossings with a range of 0.00 to 28 cm and standard deviation 0.05 cm in which 72.00% were 10 cm or less; 26.08% were between 10-20 cm.
   The maximum crossing error for Point_Aux_Chenes_South_Reef_November_2022_SBES_WGS84_UTM16N_xyz_pp.shp was 14 cm between the WVR1 and WVR2 files. The final crossing file had 274 crossings with a range of 0.00 to 14 cm and standard deviation 0.01 cm in which 99.64% were 10 cm or less; 0.36% were between 10-20 cm. All the tracklines for WVR2 (22CCT12) in this area did not have post-processed GPS, as explained in the Differentially Corrected Navigation Processing process step. The WVR1 (22CCT11) survey did have post-processed GPS data and was used as the metric to adjust the WVR2 data to correct the WVR2 lines that crossed WVR1. The following tracklines were adjusted based upon the mean of the crossings the trackline had with WVR1. The tracklines and the applied adjustment are 22CCT12_WVR2_0001_1746 by -0.21 cm, 22CCT12_WVR2_0002_1749 by -0.25 cm, 22CCT12_WVR2_0003_1751 and 22CCT12_WVR2_0004_1754 by -0.13 cm, 22CCT12_WVR2_0005_1757 by -0.19 cm, 22CCT12_WVR2_0006_1759 by -0.28 cm, 22CCT12_WVR2_0007_1802 by -0.27 cm, 22CCT12_WVR2_0008_1805 by 0.19 cm, 22CCT12_WVR2_0009_1808 by 0.10 cm, 22CCT12_WVR2_0010_1811 by 0.02 cm.
   These point shapefiles were then exported from ArcMap as xyz ASCII text (.txt) files using the XTools Pro "Table to Text" function. The resultant ASCII text file can be downloaded from this data release. Point_Aux_Chenes_2022_SBES_xyz.zip. The trackline shapefiles were exported from ArcMap and are included in Point_Aux_Chenes_2022_SBES_tracklines.zip. Person who carried out this activity:
   

   Nancy T. DeWitt

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ndewitt@usgs.gov

   Data sources used in this process:

   • 22CCT09_WVR1_SBES_WGS84_UTM16N_Level_003_xyz.txt
   • 22CCT10_WVR2_SBES_WGS84_UTM16N_Level_003_xyz.txt
   • 22CCT11_WVR1_SBES_WGS84_UTM16N_Level_003_xyz.txt
   • 22CCT12_WVR2_SBES_WGS84_UTM16N_Level_003_xyz.txt

   Data sources produced in this process:

   • Point_Aux_Chenes_June_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_North_Reef_June_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_South_Reef_June_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_South_Reef_November_2022_SBES_WGS84_UTM16N_xyz_pp.txt
   • Point_Aux_Chenes_2022_SBES_WGS84_UTM16N_Tracklines.shp
   • Point_Aux_Chenes_North_Reef_June_2022_SBES_WGS84_UTM16N_Tracklines.shp
   • Point_Aux_Chenes_South_Reef_June_2022_SBES_WGS84_UTM16N_Tracklines.shp
   • Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_Tracklines.shp
   • Point_Aux_Chenes_South_Reef_November_2022_SBES_WGS84_UTM16N_xyz_pp_Tracklines.shp

   Date: 2023 (process 6 of 9)

   Datum Transformation: NOAA/NGS's VDatum was used to transform the single-beam data points' horizontal and vertical datums (xyz) with a reported vertical uncertainty of 0.06429 m. VDatum reports a nationwide standard deviation of 2.0 centimeters (cm) for ellipsoid - NAD83 transformations, and a nationwide standard deviation of 5.0 cm for NAD83 to NAVD88 transformations in the coastal regions of the continental U.S. For more information about the positional accuracy for these datum transformations, visit the Estimation of Vertical Uncertainties VDatum webpage (https://vdatum.noaa.gov/docs/est_uncertainties.html). The resultant ASCII text data files can be downloaded from this data release in Point_Aux_Chenes_2022_SBES_xyz.zip. Person who carried out this activity:
   

   Nancy T. DeWitt

   U.S. Geological Survey

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ndewitt@usgs.gov

   Data sources used in this process:

   • Point Point_Aux_Chenes_June_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_North_Reef_June_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_South_Reef_June_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_xyz.txt
   • Point_Aux_Chenes_South_Reef_November_2022_SBES_WGS84_UTM16N_xyz.txt

   Data sources produced in this process:

   • Point_Aux_Chenes_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt
   • Point_Aux_Chenes_North_Reef_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt
   • Point_Aux_Chenes_North_Reef_November_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt
   • Point_Aux_Chenes_South_Reef_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt
   • Point_Aux_Chenes_South_Reef_November_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz_pp.txt

   Date: 2023 (process 7 of 9)

   WorldView (WV) 2 imagery from 20220511 was downloaded from Maxar’s Global Enhance Geoint Delivery (G-EGD). The imagery was radiometrically and atmospherically corrected and then pansharpened using ERDAS IMAGINE 2020 to obtain measures of ground reflectance. The output image was reprojected into the WGS84 UTM 16N coordinate system. The image was then co-registered to high-resolution aerial imagery (NAIP) using the AutoSync-workstation in ERDAS Image pixels. First, an NAIP image mosaic was created for an extent larger than the WV image coverage. Ground control points coincident on both images were used to adjust the WV image to the corresponding location on the NAIP. Control points with an error value greater than 1 were removed to generate vector shorelines from WV images, and a similar methodology described by Maglione (2014) was followed. All WV images were classified into land-water rasters using tools within Arc Map. First, normalized difference vegetation index (NDVI) was calculated using WV band 5 in the visible red spectrum (RED) and band 7 in the near-infrared spectrum (NIR1) using the following formula: NDVI=(NIR1-RED)/(NIR1+RED). Vegetation was classified as high values (above 0.2), water represented low values (usually less than -0.2), and soil was classified between the values of -0.2 and 0.2. The value of 0.21 provided an adequate representation of the shoreline (wetland-water boundary) and that value was used to reclassify the NDVI to a land-water raster. The land-water raster was processed to reduce isolated pixels by using expand-shrink procedure (Smith and others, 2021). The resulting image classified vegetated shorelines, however some shorelines within the study area were composed of sandy beach (bright, sand and shells). To improve the shoreline classification for beach shorelines, a threshold using band 8 (NIR2) was selected, which showed high reflectance for the beach and urban areas (a value of 5000 was used) and created a new land classification that was merged with the vegetated land class to create a binomial land-water raster. In ArcMap, the classification boundaries were smoothed to remove any extraneous cells missed in the expand and shrink steps. The raster was then converted into polygons, and the polygons were then converted into lines. The lines, however, still contained the ridged cell edges, so the lines were smoothed using the Polynomial Approximation with Exponential Kernel (PAEK) algorithm and a 2-meter smoothing filter (Smith and others, 2021). Shorelines not in the study area or shorelines improperly classified (such as nearshore sand shoals) were manually removed or edited. Shorelines were projected into the NAD83 UTM 16N coordinate system. Person who carried out this activity:
   

   Joseph Terrano

   U.S. Geological Survey

   Physical Scientist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8047 (voice)

   jterrano@usgs.gov

   Data sources used in this process:

   • High resolution satellite imagery derived shorelines for 2022.

   Date: 2024 (process 8 of 9)

   Shoreline Preparation: To provide the most accurate representation of the bathymetry within the nearshore areas, shoreline data was prepared and used in conjunction with the xyz data that was produced during previous processing steps. Replicating the steps from Stalk and others (2021), the shoreline polyline data was first converted to points utilizing the XTools Function "Polylines to Points". Utilizing the "Buffer" geoprocessing tool in ArcMap, 100 m and 200 m buffers were generated around the Point Aux Chenes single-beam survey tracklines from June 2022. The shoreline points were then clipped using the "Clip" geoprocessing tool to each generated buffer file to ensure only shoreline points that fall within 100 m or 200 m from a bathymetry point were utilized for further processing. The 100 m buffer was utilized as the primary distance. However, on the westernmost extent of the Bay, 200 m was a more appropriate buffer distance due to the existing data coverage. Some manual editing of the resultant shoreline point file was necessary to ensure proper representation of the bathymetry extent. Utilizing the attribute table editor and Field Calculator function, an integer field was added to the shoreline points attribute table named "NAVD88_G12A", and the field was populated with a zero-value to represent a zero elevation at the shoreline extent. The resultant point shapefile has been made available in the Point_Aux_Chenes_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.zip. The shoreline points were then converted to a polygon utilizing the XTools Pro "Points to Polygons" function to establish an extent file to be used in later processing steps. Polygon vertices were manually added using the Editor tool to the western and eastern portions of Point Aux Chenes Bay, placed at the approximate land-water intersection using provided shoreline (Smith and others, 2021), as well as along the offshore extent of the xyz data. The resultant coverage file was utilized in subsequent processing steps and has also been made available in Point_Aux_Chenes_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.zip. Person who carried out this activity:
   

   Chelsea A. Stalk

   U.S. Geological Survey

   Electronics Technician (Marine Instrumentation)

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cstalk@usgs.gov

   Data sources used in this process:

   • Point_Aux_Chenes_2022_SBES_Coverage.shp
   • Point_Aux_Chenes_2022_SBES_WGS84_UTM16N_Tracklines.shp

   Data sources produced in this process:

   • Point_Aux_Chenes_2022_Shoreline_Points.shp
   • Point_Aux_Chenes_2022_Shoreline_2022_Polyline.shp

   Date: 2024 (process 9 of 9)

   Create Digital Elevation Model: The transformed xyz ASCII text dataset from the June 2022 survey (generated in the previous processing step) was imported into ArcMap using the "Create Feature Class From XY Table" tool. That dataset, along with the generated shoreline points, were used to create a triangulated irregular network (TIN) using the "Create TIN" tool. The TIN was subsequently converted into a raster file using the "TIN to Raster" tool utilizing floating point with a cell size of 10 meters. The resultant raster was then clipped utilizing the "Extract by Mask" tool, utilizing the coverage file produced in the previous step. The final digital elevation model (DEM) was then exported from ArcMap as a 32-bit floating GeoTIFF (Geographic Tag Image File Format, .tif), utilizing the Natural Neighbor algorithm, and made available within the data downloads section of this data release (Point_Aux_Chenes_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.zip). As a part of standard QA/QC procedures, each DEM was compared to the associated xyz data, and associated root-mean-square error (RMSe) values were populated. The Point_Aux_Chenes_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM has a RMSe value of 0.039 m. Person who carried out this activity:
   

   Chelsea A. Stalk

   U.S. Geological Survey

   Electronics Technician (Marine Instrumentation)

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cstalk@usgs.gov

   Data sources used in this process:

   • Point_Aux_Chenes_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt
   • Point_Aux_Chenes_2022_Shoreline_Points.shp

   Data sources produced in this process:

   • Point_Aux_Chenes_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.tif

3. What similar or related data should the user be aware of?
   Maglione, Pasquale, Parente, Claudio, and Vallario, Andrea, 20140217, Coastline extraction using high resolutionWorldView-2 satellite imagery: European Journal of Remote Sensing Volume 47, Issue 1, Taylor & Francis, Online.

   Online Links:

   • https://doi.org/10.5721/EuJRS20144739

   Other_Citation_Details: Pages 685-699
   

   DeWitt, Nancy T., Stalk, Chelsea A., Smith, Christopher A., Locker, Stanley D., Fredericks, Jake J., McCloskey, Terrance A., and Wheaton, Cathyrn J., 2017, Single-beam bathymetry data collected in 2015 from Grand Bay, Alabama-Mississippi: U.S. Geological Survey Data Release doi:10.3133/ds1070, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.3133/ds1070

   Hansen, Mark E., DeWitt, Nancy T., and Reynolds, Billy J., 20170810, Archive of bathymetry data collected in South Florida from 1995 to 2015: U.S. Geological Survey Data Series doi:10.3133/1031, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.3133/ds1031

   Stalk, Chelsea A., Wilcox, Hunter S., Passeri, Davina L., Smith, Christopher A., Smith, Kathryn E.L., and Terrano, Joseph F., 20210916, Single-beam bathymetry data collected in March 2021 from Grand Bay and Point Aux Chenes Bay, Mississippi/Alabama: U.S. Geological Survey data release doi:10.5066/P93ZM9MK, U.S. Geological Survey – St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

   Online Links:

   • https://doi.org/10.5066/P93ZM9MK

   Smith, Kathryn E.L., Terrano, Joseph F., Pitchford, Jonathan L., and Archer, Michael J., 20210802, Coastal Wetland Shoreline Change Monitoring: A Comparison of Shorelines from High-Resolution WorldView Satellite Imagery, Aerial Imagery, and Field Surveys: Remote Sensing Volume 13, Issue 15, MDPI journals, Online.

   Online Links:

   • https://doi.org/10.3390/rs13153030

   Other_Citation_Details: Article 3030
   

   Terrano, Joseph F., Smith, Kathryn E.L., Pitchford, Jonathan L., Archer, Michael, and Brochard, Michael, 20210723, Shorelines from high-resolution WorldView satellite imagery, real-time kinematic global positioning data, and aerial imagery for 2013 to 2020 for study sites within Grand Bay National Estuarine Research Reserve, Mississippi: U.S. Geological Survey data release doi.org/10.5066/P9W8TNQM, U.S. Geological Survey – St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

   Online Links:

   • https://doi.org/10.5066/P9W8TNQM

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 was determined during data collection. This dataset is derived from three field surveys using identical equipment set-ups. Therefore, the data collection is considered internally consistent. Methods were employed to maintain data collection consistency aboard the platforms. 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 then entered digitally into their respective programs. Offsets between the single-beam transducers, motion reference units, and the antenna reference point (ARP) were measured using a geodimeter and accounted for during acquisition and (or) in post-processing. Differential Global Positioning System (DGPS) coordinates were obtained using the following post-processing software packages: NGS OPUS and NovAtel’s Waypoint Product Group GrafNav.
2. How accurate are the geographic locations?
   The NGS Permanent Identifier (PID) DO5987, stamping 0166 B 2010 (https://www.ngs.noaa.gov/OPUS/getDatasheet.jsp?PID=DO5987), was the primary base station location for this dataset. For this dataset remain consistent with the 2015 and 2021 bathymetry datasets (DeWitt and others, 2017; Stalk and others, 2021), the same base location (DO5987) and base value were used for data collection and post-processing. However, to be current with the WGS84 (G2139) realization during acquisition, the base position used to post-process navigation data during the 2015 survey (DeWitt and others, 2017) was converted from ITRF2008 (equivalent to WGS84) into WGS84 (G2139) using the Horizontal Time-Dependent Positioning (HTDP) online transformation utility. The latest realization (G2139) was introduced on 01/23/2021. The survey acquisition dates succeed this date; therefore, it is the appropriate datum realization for post-processing the navigation data. The resultant base position used for post-processing was 30°24’46.75374 North, 88°24’12.11420 West (WGS84-G2139), and -29.032 meters (m) ellipsoid height (WGS84-G2139). A secondary base station was erected on PID DP1533, stamping 5 T 2 2013, but it was not needed for post-processing. The kinematic trajectories (rover to base) were processed using Novatel’s Waypoint GrafNav software.
3. How accurate are the heights or depths?
   The ellipsoid height value of -29.032 m (WGS84-G2139) was used in NovAtel's Waypoint GrafNav software for post-processing. Please refer to the Horizontal_Positional_Accuracy_Report segment for vertical position transformation into ellipsoid height.
4. Where are the gaps in the data? What is missing?
   This data release contains single-beam bathymetry data points in the horizontal position and vertical elevation (xyz) from June 2022 and November 2022 collected within Point Aux Chenes, MS. Users are advised to read this metadata record carefully for additional details. During the November survey on WVR2 (22CCT12), the Global Navigation Satellite System (GNSS) unit stopped recording internally, so that data was not available to post-process from the rover to the base station. GPS was recorded to the HYPACK .RAW files, but only as Satellite Based Augmentation System (SBAS) which does not produce centimeter accuracy. The lines affected were not included in this data release. Please refer to the Quality Control, Quality Assurance (QA/QC) and Uncertainty Analysis process steps in this metadata record for more information. Any additional data gaps in the final product are the result of poor quality echosounder data, commonly caused by extremely shallow water limiting the survey vessel's ability to maneuver, seafloor sediment type inhibiting a good return, or instrument malfunction.
5. How consistent are the relationships among the observations, including topology?
   These data were collected under one field activity number (2022-320-FA) with four subFANs (June: 22CCT09 and 22CCT10; November: 22CCT11 and 22CCT12) each with consistent instrument calibrations. Users should be aware that comparisons with other datasets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time.

How can someone get a copy of the data set?

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

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   gs-g-spcmsc_data_inquiries@usgs.gov
2. What's the catalog number I need to order this data set? Point_Aux_Chenes_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.tif, Point_Aux_Chenes_June_2022_ShorelinePoints.shp, Point_Aux_Chenes_June_2022_Shoreline_Polyline.shp, Point_Aux_Chenes_2022_SBES_Coverage.shp, Point_Aux_Chenes_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt, Point_Aux_Chenes_North_Reef_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt, Point_Aux_Chenes_North_Reef_November_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt, Point_Aux_Chenes_South_Reef_June_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz.txt, Point_Aux_Chenes_South_Reef_November_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_xyz_pp.txt, Point_Aux_Chenes_June_2022_SBES_WGS84_UTM16N_xyz.txt, Point_Aux_Chenes_North_Reef_June_2022_SBES_WGS84_UTM16N_xyz.txt, Point_Aux_Chenes_South_Reef_June_2022_SBES_WGS84_UTM16N_xyz.txt, Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_xyz.txt, Point_Aux_Chenes_South_Reef_November_2022_SBES_WGS84_UTM16N_xyz_pp.txt, Point_Aux_Chenes_2022_SBES_WGS84_UTM16N_Tracklines.shp, Point_Aux_Chenes_North_Reef_June_2022_SBES_WGS84_UTM16N_Tracklines.shp, Point_Aux_Chenes_South_Reef_June_2022_SBES_WGS84_UTM16N_Tracklines.shp, Point_Aux_Chenes_North_Reef_November_2022_SBES_WGS84_UTM16N_Tracklines.shp, and Point_Aux_Chenes_South_Reef_November_2022_SBES_WGS84_UTM16N_xyz_pp_Tracklines.shp
3. What legal disclaimers am I supposed to read?
   This digital publication was prepared by an agency of the United States Government. Although these data were 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?
   • Availability in digital form:

     Data format:	comma-delimited text, shapefile, and GeoTIFF
     Network links:	https://coastal.er.usgs.gov/data-release/doi-P13NPYMZ/data/Point_Aux_Chenes_2022_SBES_xyz.zip https://coastal.er.usgs.gov/data-release/doi-P13NPYMZ/data/Point_Aux_Chenes_2022_SBES_tracklines.zip https://coastal.er.usgs.gov/data-release/doi-P13NPYMZ/data/Point_Aux_Chenes_2022_SBES_NAD83_NAVD88_GEOID12A_UTM16N_10m_DEM.zip

   • Cost to order the data: None

Who wrote the metadata?

Dates:

Last modified: 08-Jul-2024

Metadata author:

U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center

Attn: USGS SPCMSC Data Management

600 4th Street South

St. Petersburg, FL

USA

727-502-8000 (voice)

gs-g-spcmsc_data_inquiries@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)